Co-reporter:Wenkai Zhong, Kang Li, Jing Cui, Tianyi Gu, Lei Ying, Fei Huang, and Yong Cao
Macromolecules October 24, 2017 Volume 50(Issue 20) pp:8149-8149
Publication Date(Web):October 5, 2017
DOI:10.1021/acs.macromol.7b01432
We developed a novel wide-bandgap conjugated polymer PTzBI-O based on an alkoxylated electron-deficient monomer 4,8-di(thiophen-2-yl)-[1,2,3]triazolo[4,5-f]isoindole-5,7(2H,6H)-dione (TzBI-O). Regarding that of alkyl-substituted imide-functionalized benzotriazole (TzBI) unit, the incorporation of oxygen atom into the substitution of TzBI-O increased the electronegativity. The resulting polymer PTzBI-O exhibited an absorption onset of 708 nm, corresponding to a bandgap of 1.75 eV. The PTzBI-O:N2200 blend exhibited strong aggregation in toluene solution, resulting in the enhanced absorptivity in thin film compared to those of equivalent films processed with chlorinated solvents. The fabricated all-polymer solar cell based on PTzBI-O:N2200 blend film processed with toluene exhibited an impressive power conversion efficiency of 7.91%. The higher efficiency of the toluene-processed device than those based on films processed with chlorinated solvents can be attributed to more effective charge dissociation, trivial bimolecular recombination, greater charge transportation, and more favorable thin film morphology of the toluene-cast blend film. These findings indicated that the resulting copolymer has great potential for the construction of high-performance all-polymer solar cells.
Co-reporter:Tao Jia, Chen Sun, Rongguo Xu, Zhiming Chen, Qingwu Yin, Yaocheng Jin, Hin-Lap Yip, Fei Huang, and Yong Cao
ACS Applied Materials & Interfaces October 18, 2017 Volume 9(Issue 41) pp:36070-36070
Publication Date(Web):September 26, 2017
DOI:10.1021/acsami.7b10365
A series of naphthalene diimide (NDI) based n-type conjugated polymers with amino-functionalized side groups and backbones were synthesized and used as cathode interlayers (CILs) in polymer and perovskite solar cells. Because of controllable amine side groups, all the resulting polymers exhibited distinct electronic properties such as oxidation potential of side chains, charge carrier mobilities, self-doping behaviors, and interfacial dipoles. The influences of the chemical variation of amine groups on the cathode interfacial effects were further investigated in both polymer and perovskite solar cells. We found that the decreased electron-donating property and enhanced steric hindrance of amine side groups substantially weaken the capacities of altering the work function of the cathode and trap passivation of the perovskite film, which induced ineffective interfacial modifications and declining device performance. Moreover, with further improvement of the backbone design through the incorporation of a rigid acetylene spacer, the resulting polymers substantially exhibited an enhanced electron-transporting property. Upon use as CILs, high power conversion efficiencies (PCEs) of 10.1% and 15.2% were, respectively, achieved in polymer and perovskite solar cells. Importantly, these newly developed n-type polymers were allowed to be processed over a broad thickness range of CILs in photovoltaic devices, and a prominent PCE of over 8% for polymer solar cells and 13.5% for perovskite solar cells can be achieved with the thick interlayers over 100 nm, which is beneficial for roll-to-roll coating processes. Our findings contribute toward a better understanding of the structure–performance relationship between CIL material design and solar cell performance, and provide important insights and guidelines for the design of high-performance n-type CIL materials for organic and perovskite optoelectronic devices.Keywords: amine side groups; aphthalene diimide; cathode interlayers; perovskite solar cells; polymer solar cells;
Co-reporter:Wenkai Zhong, Jing Cui, Baobing Fan, Lei Ying, Yu Wang, Xue Wang, Guichuan Zhang, Xiao-Fang Jiang, Fei Huang, and Yong Cao
Chemistry of Materials October 10, 2017 Volume 29(Issue 19) pp:8177-8177
Publication Date(Web):September 12, 2017
DOI:10.1021/acs.chemmater.7b02228
We developed a novel nonfullerene electron acceptor, IffBR, that consists of electron-rich indaceno[1,2-b:5,6-b′]dithiophene as the central unit and an electron-deficient 5,6-difluorobenzo[c][1,2,5]thiadiazole unit flanked with rhodanine as the peripheral group. IffBR exhibits peak UV–vis absorbance at 658 nm, which is complementary with the absorption profiles of the wide-bandgap conjugated polymers poly[4,8-bis(4,5-dihexylthiophen-2-yl)benzo[1,2-b:4,5-b′]-dithiophene-alt-2-(2-butyloctyl)-5,6-difluoro-4,7-di(thiophen-2-yl)-2H-benzo[d][1,2,3]triazole] (PBTA-BO) and the fullerene acceptor [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). The ternary device constructed with PBTA-BO/PC71BM/IffBR as the light-absorption layer exhibited significantly better photovoltaic performance than those obtained from devices based on a bulk-heterojunction layer comprised of binary components. This improvement was attributed to the broadened absorbance, formation of cascade charge-transfer pathways, reduced nongeminate recombination, enhanced charge extraction, and more favorable morphologies of the bulk-heterojunction films. The optimized ternary device exhibited a power conversion efficiency of 9.06%, which is significantly higher than those of binary devices based on either PBTA-BO/IffBR (6.24%) or PBTA-BO/PC71BM (4.73%). These results indicate that IffBR is an outstanding electron acceptor, suitable for the fabrication of nonfullerene or multicomponent-blend polymer solar cells.
Co-reporter:Kai Zhang;Zhicheng Hu;Chen Sun;Zhihong Wu;Yong Cao
Chemistry of Materials January 10, 2017 Volume 29(Issue 1) pp:141-148
Publication Date(Web):September 8, 2016
DOI:10.1021/acs.chemmater.6b02802
With the rapid development of polymer solar cells (PSCs), the manufacture of high-performance large area PSC modules is becoming a critical issue in commercial applications. However, most of the reported light absorption materials and interfacial materials are quite thickness sensitive, with optimal thicknesses of around 100 and 5 nm, respectively. The thickness need to be precisely controlled, otherwise, a small variation in thickness can often lead to a sharp decrease in device performance, especially for interfacial materials. This increases the difficulty of apply these materials in the production of large area PSCs. To avoid the shortcomings of thickness-sensitive materials and achieve high-performance large area PSC modules, we designed and synthesized a series of high mobility donor materials and cathode interfacial materials. These materials exhibited excellent device performance at their optimal thicknesses and maintained high performance even with large thickness variations, thus providing a solution to the bottleneck problem in manufacturing PSC modules and enhancing the device reproducibility. We also developed a simple and efficient approach for achieving a large area cathode interlayer with controlled film composition, uniformity, and thickness at the nanometer-scale using an electrostatic layer-by-layer self-assembly (eLbL) process. The eLbL films exhibited excellent cathode modification ability and can be integrated into the current large area device processing techniques. Thus, our approaches from both material design to device engineering provide new solutions for preparing high-performance large area PSC modules.
Co-reporter:Guichuan Zhang, Kai Zhang, Qingwu Yin, Xiao-Fang Jiang, Zaiyu Wang, Jingming Xin, Wei Ma, He Yan, Fei Huang, and Yong Cao
Journal of the American Chemical Society February 15, 2017 Volume 139(Issue 6) pp:2387-2387
Publication Date(Web):January 27, 2017
DOI:10.1021/jacs.6b11991
Ternary organic solar cells (OSCs) have attracted much research attention in the past few years, as ternary organic blends can broaden the absorption range of OSCs without the use of complicated tandem cell structures. Despite their broadened absorption range, the light harvesting capability of ternary OSCs is still limited because most ternary OSCs use thin active layers of about 100 nm in thickness, which is not sufficient to absorb all photons in their spectral range and may also cause problems for future roll-to-roll mass production that requires thick active layers. In this paper, we report a highly efficient ternary OSC (11.40%) obtained by incorporating a nematic liquid crystalline small molecule (named benzodithiophene terthiophene rhodanine (BTR)) into a state-of-the-art PTB7-Th:PC71BM binary system. The addition of BTR into PTB7-Th:PC71BM was found to improve the morphology of the blend film with decreased π–π stacking distance, enlarged coherence length, and enhanced domain purity. This resulted in more efficient charge separation, faster charge transport, and less bimolecular recombination, which, when combined, led to better device performance even with thick active layers. Our results show that the introduction of highly crystalline small molecule donors into ternary OSCs is an effective means to enhance the charge transport and thus increase the active layer thickness of ternary OSCs to make them more suitable for roll-to-roll production than previous thinner devices.
Co-reporter:Baobing Fan;Wenkai Zhong;Xiao-Fang Jiang;Qingwu Yin;Lei Ying;Yong Cao
Advanced Energy Materials 2017 Volume 7(Issue 11) pp:
Publication Date(Web):2017/06/01
DOI:10.1002/aenm.201602127
Efficient ternary polymer solar cells are constructed by incorporating an electron-deficient chromophore (5Z,5′Z)-5,5′-((7,7′-(4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)bis(6-fluorobenzo[c][1,2,5]thiadiazole-7,4-diyl))bis(methanylylidene))bis(3-ethyl-2-thioxothiazolidin-4-one) (IFBR) as an additional component into the bulk-heterojunction film that consists of a wide-bandgap conjugated benzodithiophene-alt-difluorobenzo[1,2,3]triazole based copolymer and a fullerene acceptor. With respect to the binary blend films, the incorporation of a certain amount of IFBR leads to simultaneously enhanced absorption coefficient, obviously extended absorption band, and improved open-circuit voltage. Of particular interest is that devices based on ternary blend film exhibit much higher short-circuit current densities than the binary counterparts, which can be attributed to the extended absorption profiles, enhanced absorption coefficient, favorable film morphology, as well as formation of cascade energy level alignment that is favorable for charge transfer. Further investigation indicates that the ternary blend device exhibits much shorter charge carrier extraction time, obviously reduced trap density and suppressed trap-assisted recombination, which is favorable for achieving high short-circuit current. The combination of these beneficial aspects leads to a significantly improved power conversion efficiency of 8.11% for the ternary device, which is much higher than those obtained from the binary counterparts. These findings demonstrate that IFBR can be a promising electron-accepting material for the construction of ternary blend films toward high-performance polymer solar cells.
Co-reporter:Baobing Fan;Lei Ying;Peng Zhu;Feilong Pan;Feng Liu;Junwu Chen;Yong Cao
Advanced Materials 2017 Volume 29(Issue 47) pp:
Publication Date(Web):2017/12/01
DOI:10.1002/adma.201703906
AbstractA novel wide-bandgap conjugated copolymer based on an imide-functionalized benzotriazole building block containing a siloxane-terminated side-chain is developed. This copolymer is successfully used to fabricate highly efficient all-polymer solar cells (all-PSCs) processed at room temperature with the green-solvent 2-methyl-tetrahydrofuran. When paired with a naphthalene diimide-based polymer electron-acceptor, the all-PSC exhibits a maximum power conversion efficiency (PCE) of 10.1%, which is the highest value so far reported for an all-PSC. Of particular interest is that the PCE remains 9.4% after thermal annealing at 80 °C for 24 h. The resulting high efficiency is attributed to a combination of high and balanced bulky charge carrier mobility, favorable face-on orientation, and high crystallinity. These observations indicate that the resulting copolymer can be a promising candidate toward high-performance all-PSCs for practical applications.
Co-reporter:Baobing Fan;Kai Zhang;Xiao-Fang Jiang;Lei Ying;Yong Cao
Advanced Materials 2017 Volume 29(Issue 21) pp:
Publication Date(Web):2017/06/01
DOI:10.1002/adma.201606396
High-performance nonfullerene polymer solar cells (PSCs) are developed by integrating the nonfullerene electron-accepting material 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2′,3′-d′]-s-indaceno[1,2-b:5,6-b′]dithiophne) (ITIC) with a wide-bandgap electron-donating polymer PTzBI or PTzBI-DT, which consists of an imide functionalized benzotriazole (TzBI) building block. Detailed investigations reveal that the extension of conjugation can affect the optical and electronic properties, molecular aggregation properties, charge separation in the bulk-heterojunction films, and thus the overall photovoltaic performances. Single-junction PSCs based on PTzBI:ITIC and PTzBI-DT:ITIC exhibit remarkable power conversion efficiencies (PCEs) of 10.24% and 9.43%, respectively. To our knowledge, these PCEs are the highest efficiency values obtained based on electron-donating conjugated polymers consisting of imide-functionalized electron-withdrawing building blocks. Of particular interest is that the resulting device based on PTzBI exhibits remarkable PCE of 7% with the thickness of active layer of 300 nm, which is among the highest values of nonfullerene PSCs utilizing thick photoactive layer. Additionally, the device based on PTzBI:ITIC exhibits prominent stability, for which the PCE remains as 9.34% after thermal annealing at 130 °C for 120 min. These findings demonstrate the great promise of using this series of wide-bandgap conjugated polymers as electron-donating materials for high-performance nonfullerene solar cells toward high-throughput roll-to-roll processing technology.
Co-reporter:
Journal of Polymer Science Part A: Polymer Chemistry 2017 Volume 55(Issue 4) pp:660-671
Publication Date(Web):2017/02/15
DOI:10.1002/pola.28363
ABSTRACTIn this manuscript we reported the synthesis of diethynylbenzo[1,2-b:4,5-b′]dithiophene(DEBDT)-based small molecule BDTTIPS and three new cross-conjugated copolymers PBDTE-Th, PBDTE-FBT, and PBDTE-DPP that consist of DEBDT unit. The thermal, optophysical, and electronic properties of these materials were systematically investigated. The small molecule BDTTIPS exhibited higher absorption coefficient than the cross-conjugated copolymers. The LUMO/HOMO energy levels of such three cross-conjugated copolymers were −3.74/5.51, −3.77/–5.53, and −4.02/–5.58 eV as estimated from cyclic voltammetry measurements, which were lower than that of −3.63/–5.39 eV for the small molecule BDTTIPS. Due to the unique molecular structure and electronic properties of cross-conjugated polymers, hole mobilities of PBDTE-Th and PBDTE-DPP were higher than that of BDTTIPS. Photovoltaic performances were investigated by fabricating organic solar cells with the configuration of ITO/PEDOT:PSS/donor:PC61BM/Ca/Al. The small molecule chromophore BDTTIPS exhibited a power conversion efficiency of 4.19%, which was much higher than those obtained from devices based on conjugated polymers as the photoactive layer. These observations indicated that the DEBDT can be a promising building block for the construction of organic semiconducting materials for organic solar cell applications, and the rational molecular design was required for the attainment of high photovoltaic performances. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 660–671
Co-reporter:Dan Li;Chen Sun;Hao Li;Hui Shi;Xuxia Shai;Qiang Sun;Junbo Han;Yan Shen;Hin-Lap Yip;Mingkui Wang
Chemical Science (2010-Present) 2017 vol. 8(Issue 6) pp:4587-4594
Publication Date(Web):2017/05/30
DOI:10.1039/C7SC00077D
In this study, for the first time, we report a solution-processed amino-functionalized copolymer semiconductor (PFN-2TNDI) with a conjugated backbone composed of fluorine, naphthalene diimide, and thiophene spacers as the electron transporting layer (ETL) in n–i–p planar structured perovskite solar cells. Using this copolymer semiconductor in conjunction with a planar n–i–p heterojunction, we achieved an unprecedented efficiency of ∼16% under standard illumination test conditions. More importantly, the perovskite devices using this polymer ETL have shown good stability under constant ultra violet (UV) light soaking during 3000 h of accelerated tests. Various advanced spectroscopic characterizations, including ultra-fast spectroscopy, ultra-violet photoelectron spectroscopy and electronic impedance spectroscopy, elucidate that the interaction between the functional polymer ETL and the perovskite layer plays a critical role in trap passivation and thus, the device UV-photostability. We expect that these results will boost the development of low temperature solution-processed organic ETL materials, which is essential for the commercialization of high-performance and stable, flexible perovskite solar cells.
Co-reporter:Baobing Fan;Lei Ying;Zhenfeng Wang;Baitian He;Xiao-Fang Jiang;Yong Cao
Energy & Environmental Science (2008-Present) 2017 vol. 10(Issue 5) pp:1243-1251
Publication Date(Web):2017/05/17
DOI:10.1039/C7EE00619E
Increasing interest has been devoted to developing high-performance all-polymer solar cells (all-PSCs) owing to their specific advantages in light absorption and long-term stability. In this work, we systematically investigated the synergistic effects of processing solvents and molecular weight on the photovoltaic performance of all-PSCs, which consist of an n-type polymer N2200 and a p-type wide bandgap polymer PTzBI that are made up of benzodithiophene and imide-functionalized benzotriazole units. It is noted that increasing the molecular weight of N2200 can simultaneously enhance exciton generation and dissociation, reduce bimolecular recombination, and facilitate charge extraction. The films processed with the environmentally-friendly solvent 2-methyl-tetrahydrofuran (MeTHF) exhibit a more favourable film morphology than those processed with commonly used halogenated solvents. The all-PSC consisting of the high molecular weight N2200 and PTzBI processed with the environmentally friendly solvent MeTHF presents a remarkable power conversion efficiency of 9.16%, which is the highest value so far observed for all-PSCs. Of particular interest is that the PCE remains 6.37% with the active layer thickness of 230 nm. These observations imply the great promise of the developed all-PSCs for practical applications toward high-throughput roll-to-roll technology.
Co-reporter:Renlong Li;Gongchu Liu;Manjun Xiao;Xiye Yang;Xiang Liu;Zhenfeng Wang;Lei Ying;Yong Cao
Journal of Materials Chemistry A 2017 vol. 5(Issue 45) pp:23926-23936
Publication Date(Web):2017/11/21
DOI:10.1039/C7TA06631G
We designed and synthesized two novel non-fullerene small molecule acceptors (IDT-N and IDT-T-N) that consist of indacenodithiophene (IDT) as the electron-donating core and 2-(3-oxo-2,3-dihydro-1H-cyclopenta[b]naphthalen-1-ylidene)malononitrile (N) as a novel electron-withdrawing end group. IDT-N and IDT-T-N consisting of the naphthyl-based N group exhibited an expanded plane compared to phenyl-based indanone (INCN), which strengthened the intramolecular push–pull effect between the core donor unit and the terminal acceptor units. This strengthened effect resulted in a reduced bandgap that was beneficial for solar photon collection and increased short-circuit current density of the resulting devices. IDT-N and IDT-T-N exhibited red-shifted absorptions and smaller optical bandgaps than the corresponding phenyl-fused indanone end-capped chromophores. Both acceptors exhibited broad absorptions and energy levels that were well-matched with the donor materials. Polymer solar cells based on IDT-N and IDT-T-N and two representative polymer donors (PTB7-Th and PBDB-T) exhibited impressive photovoltaic performances. The devices based on the PBDB-T:IDT-N system exhibited a power conversion efficiency of up to 9.0%, with a short-circuit current density of 15.88 mA cm−2 and a fill factor of 71.91%. These results demonstrate that IDT-N and IDT-T-N are promising electron acceptors for use in polymer solar cells.
Co-reporter:Xi Liu;Tao Liu;Chunhui Duan;Junyi Wang;Shuting Pang;Wentao Xiong;Yanming Sun;Yong Cao
Journal of Materials Chemistry A 2017 vol. 5(Issue 4) pp:1713-1723
Publication Date(Web):2017/01/24
DOI:10.1039/C6TA08739F
Three perylenediimide (PDI) acceptors (P2O2, P2N2 and P4N4) were synthesized by functionalizing the bay positions of PDI with benzil, 2,3-diphenylquinoxaline and 2,3,7,8-tetraphenylpyrazino[2,3-g]quinoxaline as linkers, respectively. The photovoltaic properties of the three acceptor molecules have been investigated. The different PDI linker units show different physical and chemical properties of the PDIs. The three PDIs display different non-planar geometrical structures because of the different linker units, which affect the corresponding morphology of the blend films and also influence the charge mobility and fill factor (FF) of the organic solar cells (OSCs). Furthermore, the gradient energy levels of the three PDIs provide an efficient research model for the relationship of device open-circuit voltage (Voc) and energy levels. As the result, the P4N4 based non-fullerene devices show the best photovoltaic performance with a power conversion efficiency (PCE) of 5.71%, whereas the P2O2 and P2N2 based non-fullerene devices show relatively lower PCEs of 2.53% and 3.86%, respectively.
Co-reporter:Liqian Liu;Guichuan Zhang;Baitian He;Shengjian Liu;Chunhui Duan
Materials Chemistry Frontiers 2017 vol. 1(Issue 3) pp:499-506
Publication Date(Web):2017/03/09
DOI:10.1039/C6QM00130K
The field of polymer solar cells has undergone tremendous advancement in terms of power conversion efficiency in the past decade. However, there is still an urgent requirement to further enhance device performance for achieving large-scale commercialization. Here, we report the design and synthesis of three novel conjugated polymers alternatively copolymerized by a newly developed 2,3,8,9-tetrakis(3-(alkoxy)phenyl)-6,12-di(thiophen-2-yl)-2,3,8,9-tetrahydroquinoxalino[6,5-f]quinoxaline (DTNQx) acceptor unit and a conventional two-dimensional alkylthienyl-substituted benzodithiophene (BDT) unit. These polymers possess an identical main chain but different side chains. The structure–property relationship is systematically studied. All polymers exhibit an optical bandgap around 1.7 eV and a HOMO energy level around −5.16 eV. Compared with the quinoxaline unit, fused quinoxaline DTNQx leads to a downshifted HOMO energy level in the resulting polymers by 0.04 eV while keeping the bandgap unchanged. By changing the side chain length and by introducing branched side chains, polymer properties including absorption spectra and hole mobilities could be finely tuned. Under optimal conditions, polymer P2 shows the highest hole mobility of 2.7 × 10−4 cm2 V−1 s−1 and the best photovoltaic performance, with Jsc = 9.1 mA cm−2, Voc = 0.88 V, FF = 48%, and PCE = 3.8%.
Co-reporter:Baitian He;Qingwu Yin;Xiye Yang;Liqian Liu;Xiao-Fang Jiang;Jie Zhang;Yong Cao
Journal of Materials Chemistry C 2017 vol. 5(Issue 34) pp:8774-8781
Publication Date(Web):2017/08/31
DOI:10.1039/C7TC02915B
To achieve efficient non-fullerene polymer solar cells (NF-PSCs), it is important to design and synthesize donor materials. To investigate the substituent effects of electron-withdrawing fluorine atoms and different alkyl chains (–C8C12 or –C10C14) on the thiophene π bridge, four novel conjugated polymers composed of dicyanodistyrylbenzene (DCB)-based and quinoxaline-based units were synthesized and applied in NF-PSC photovoltaic devices. It was found that the different alkyl side groups had a minimal influence on the molecular energy level but a moderate effect on the absorption coefficient, whereas the highest occupied molecular orbital (HOMO) of the resulting copolymers could be effectively lowered by introducing highly electronegative fluorine atoms into the quinoxaline moiety. As a result, the NF-PSCs based on the fluorinated quinoxaline-based copolymer exhibited high open-circuit voltages (VOC) of up to 1.043 V, which is the highest value to date for devices based on quinoxaline moiety copolymers. Moreover, fluorination also improved the copolymer carrier mobility and absorption coefficient, leading to enhanced JSC and FF, thus giving rise to higher overall efficiencies. NF-PSCs based on PDCB-DFQ812:ITIC exhibited the best performance, with a power conversion efficiency (PCE) of 8.37%. Our comparative research indicates that fluorinated quinoxaline-based conjugated polymers are promising donor materials for NF-PSCs.
Co-reporter:Zhicheng Hu;Rongguo Xu;Sheng Dong;Kai Lin;Jinju Liu;Yong Cao
Materials Horizons (2014-Present) 2017 vol. 4(Issue 1) pp:88-97
Publication Date(Web):2017/01/03
DOI:10.1039/C6MH00434B
Perylene diimide (PDI) based semiconductors with high mobility are promising electron-transporting materials (ETMs), which are used to fabricate polymer solar cells (PSCs) using roll-to-roll (R2R) processing. However, PDI-based molecular semiconductors have a strong tendency to aggregate, which hinders their use as ETMs in the fabrication of high-performance thin-film devices. Additionally, multi-layer organic opto-electronic devices require that the materials for different layers should possess orthogonal solubility. Here, we develop an in situ polymerisation method to successfully prepare ion-containing PDI-based polyelectrolytes with good water/alcohol solubility, which can enable high-performance PSCs. The doping behaviour, self-assembling and charge-transporting properties of these polyelectrolytes can be fine-tuned by their anions, which allows the fabrication of high-quality and high-mobility electron-transporting thin films for PSCs. PSCs with these polyelectrolytes can maintain high power conversion efficiencies of over 8% when the thickness of the polyelectrolyte is up to 50 nm, which offers a remarkable processing window for the mass-fabrication of PSCs using R2R techniques. Our findings on the structure–property–performance relationships of these polyelectrolytes provide insights and guidelines for the design of high-performance n-type polyelectrolytes for organic opto-electronic devices.
Co-reporter:Qiang Tao, Manjun Xiao, Mengbing Zhu, Lin Shao, Zhaoyang Sui, Pu Wang, Gongyue Huang, Yong Pei, Weiguo Zhu, Fei Huang
Dyes and Pigments 2017 Volume 144(Volume 144) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.dyepig.2017.05.012
•Two indacenodithiophene(IDT)-centered small molecules with a D(A- Ar)2 framework were first prepared.•Effect of carbazole (Cz) terminal group with increasing dipole moment on photovoltaic performance is studied.•Effect of fluorine atom at benzothiadiazole (BT) acceptor unit on photovoltaic performance is investigated.•A power conversion efficiency of 5.99% with a open-circuit voltage of 0.95 V is obtained in the IDT(DFBT-T3Cz)2 cells.Two small molecules (SMs) of IDT(BT-T3Cz)2 and IDT(DFBT-T3Cz)2 with a D(A-Ar)2 framework were designed and synthesized as a novel class of photovoltaic donor materials, which contain a donor (D) core of indacenodithiophene (IDT), two acceptor (A) arms of benzothiadiazole (BT) or fluorinated benzothiadiazole (DFBT), and two terminals of 3-carbazole (Cz). The impacts of 3-carbazole and fluorine atom on the optical absorption, electrochemical property, hole mobility, film morphology, and solar cell performance were primarily studied. A broad absorption profile in a range of 350–750 nm and a low HOMO energy level around −5.30 eV were observed for both SMs. In comparison to the reported SM of IDT(BT-Th2)2 with 5-alkyl-thiophene terminal, both SMs with 3-carbazole terminal exhibited stronger molecular packing and better self-assembly behavior owing to the increasing dipole moment of carbazole. Furthermore, the IDT(DFBT-T3Cz)2 showed a higher power conversion efficiency (PCE) of 5.99% with an increasing fill factor (FF) of 59.6% than IDT(BT-T3Cz)2 in their solar cells under the illumination of AM 1.5G at 100 mWcm−2. To the best of our knowledge, this is one of the highest PCE value reported for the IDT based SMs in solution-processed bulk heterojunction solar cells. And this work provides an efficient strategy to improve self-assembly behavior and photovoltaic performance via increasing dipole moment of the terminal groups.Two novel photovoltaic small molecular donors of IDT(BT-T3Cz)2 and IDT(DFBT- T3Cz)2, with a D(A-Ar)2 framework were prepared. Both SMs exhibit well molecular packing and self-assembly behavior. The best photovoltaic performance with a PCE of 5.99% was obtained in the IDT(DFBT-T3Cz)2 based solar cells with a high FF up to 59.6%.Download high-res image (266KB)Download full-size image
Co-reporter:Huan Chang, Zhiming Chen, Xiye Yang, Qingwu Yin, Jie Zhang, Lei Ying, Xiao-Fang Jiang, Baomin Xu, Fei Huang, Yong Cao
Organic Electronics 2017 Volume 45(Volume 45) pp:
Publication Date(Web):1 June 2017
DOI:10.1016/j.orgel.2017.03.022
•Two PDI-based n-type copolymers containing the ethynyl unit were developed.•These copolymers can be used as electron-accepting materials for all-PSCs.•The power conversion efficiency over 5% was achieved based on PPDI-F.We designed and synthesised two n-type donor-acceptor copolymers based on perylenediimide (PDI). These copolymers contained an ethynyl moiety as the π-bridge between PDI and the electron-donating unit of either benzodithiophene (BDT) or fluorine (F), with the corresponding polymers denoted as PPDI-BDT and PPDI-F, respectively. The molecular geometry and the optical and electrochemical properties of the polymers were affected by the electron-donating unit. Both copolymers exhibited relatively broad light-absorption profiles and deep lowest unoccupied molecular orbital energy levels of about −3.8 eV. All-polymer solar cells (all-PSCs) were fabricated using these copolymers as the electron-accepting material and a medium-bandgap conjugated polymer, PBDB-T, as the electron-donating material. The resulting all-PSC based on PPDI-F exhibited a power conversion efficiency of 5.09%, which is significantly higher than that of the device fabricated using PPDI-BDT (2.73%). This improvement was attributed to the higher open-circuit voltage, greater charge carrier mobility and more effective charge transfer of the PBDB-T:PPDI-F blend film. These results suggest that the developed n-type PDI-based copolymers are promising candidates as electron-accepting materials for the construction of high-performance all-polymer solar cells.Download high-res image (278KB)Download full-size image
Co-reporter:Jinju Liu;Nannan Zheng;Zhicheng Hu;Zhenfeng Wang;Xiye Yang
Science China Chemistry 2017 Volume 60( Issue 8) pp:1136-1144
Publication Date(Web):03 July 2017
DOI:10.1007/s11426-017-9057-1
Two naphthalene diimide (NDI) and perylene diimide (PDI) based n-type water/alcohol soluble small molecules (NFN and PFP) are designed and utilized as electron transport layers (ETLs) for organic solar cells (OSCs). NFN and PFP are synthesized by using Sonogashira coupling from alkynyl modified fluorene with mono-bromo substituted NDI and PDI. Density functional theory study results of NFN and PFP show that they possess excellent planarity due to the employment of triple bonds as connection units. Moreover, it was shown by electron paramagnetic resonance study that both NFN and PFP possess obvious self-doping behaviors, which may effectively enhance their charge transporting capability as ETLs in OSCs. Power conversion efficiencies of 8.59% and 9.80% can be achieved for OSCs with NFN and PFP as ETLs, respectively. The higher power conversion efficiency (PCE) of PFP based photovoltaic device is originated from the stronger doping property and higher mobility of PFP.
Co-reporter:Tao Jia;Nan-nan Zheng;Wan-qing Cai;Jie Zhang
Chinese Journal of Polymer Science 2017 Volume 35( Issue 2) pp:269-281
Publication Date(Web):2017 February
DOI:10.1007/s10118-017-1890-0
We present a microwave-assisted one-pot polymerization with three-components of alkynes, aldehydes and amines for the synthesis of new amino-functionalized optoelectronic polymers. The polymerization of diynes (1a−1c, dialdehydes (2a and 2b and dibenzylamine catalyzed by InCl3 was carried out smoothly within 1 h under microwave radiation, yielding four soluble polymers with high molecular weights. The resulting polymers P1 and P2 could be easily dissolved in alcohol and thus utilized as the cathode interlayer for polymer solar cells (PSCs). Compared with the control device, the PSCs with P1 and P2 as the cathode interlayer and PTB7-Th:PC71BM as the photoactive layer exhibited significantly higher power conversion efficiencies (PCEs) of 9.49% and 9.16%, respectively. These results suggest that this polycoupling reaction is an efficient approach to construct three-component polymers for the practical applications.
Co-reporter:Qinfen Li;Jiake Wu;Ruihan Wu;Yujing Liu;Hongzheng Chen
Science China Chemistry 2017 Volume 60( Issue 4) pp:490-496
Publication Date(Web):2017 April
DOI:10.1007/s11426-016-9018-y
Contact resistance at the interface between metal electrodes and semiconductors can significantly limit the performance of organic field-effect transistors, leading to a distinct voltage drop at the interface. Here, we demonstrate enhanced performance of n-channel field-effect transistors based on solution-grown C60 single-crystalline ribbons by introducing an interlayer of a conjugated polyelectrolyte (CPE) composed of poly[(9,9-bis(3′-((N,N-dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] dibromide (PFN+Br−). The PFN+Br− interlayer greatly improves the charge injection. Consequently, the electron mobility is promoted up to 5.60 cm2 V−1 s−1 and the threshold voltage decreased dramatically with the minimum of 4.90 V.
Co-reporter:Fei Huang
Science China Chemistry 2017 Volume 60( Issue 4) pp:433-434
Publication Date(Web):2017 April
DOI:10.1007/s11426-016-0518-6
Co-reporter:Fei Huang;Yong Cao
Science China Chemistry 2017 Volume 60( Issue 4) pp:431-432
Publication Date(Web):2017 April
DOI:10.1007/s11426-017-9040-2
Co-reporter:Kai Lin, Jing Wang, Zhicheng Hu, Rongguo Xu, Jinju Liu, Xiang Liu, Baomin Xu, Fei Huang, Yong Cao
Solar Energy Materials and Solar Cells 2017 Volume 168(Volume 168) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.solmat.2017.03.035
•Cross-linked films are prepared under mild condition.•The cross-linked film can efficiently modify ITO.•The amine density of the cross-linked film matters a lot.•High PCE of 9.37% can be reached for PSCs with modified ITO.The modification of metal/metal oxide electrode is of great importance to the performance of inverted organic optoelectronic devices. Cross-linked films provide good chance to modify the metal/metal oxide electrode and enable the fabrication of high-performance multi-layer organic optoelectronic devices due to its superior ability to resist solvent erosion. However, most of the reported methods to prepare cross-linked films are suffering from harsh processing conditions such as high-temperature thermal treatment or long-time UV radiation. Here, we develop novel robust cross-linked thin films which are prepared from an epoxy-functionalized conjugated polymer (PFEX) and an amine-based small molecule (TAA). The cross-linking processing can be realized under mild heating due to the highly-efficient amine-epoxide reaction, and the resulting cross-linked films show good solvent resistibility. Moreover, the cross-linked films showed large tolerance with the composition of PFEX and TAA, which provides opportunity to modify the metal/metal oxide electrodes in a wide range using the cross-linked films. The modified indium tin oxide (ITO) using the cross-linked films show much lowered work function and hydrophobic property than pristine ITO, which indicates great potential application in inverted organic optoelectronic devices. Inverted polymer solar cells (IPSCs) using the modified ITO show remarkable enhanced power conversion efficiency (9.4%) than those with pristine ITO (6.8%). Our design and preparation of the novel cross-linked films and the finding on the correlation between cross-linked film and photovoltaic performance will be useful to design and prepare high-performance cross-linked films for inverted organic optoelectronic devices.
Co-reporter:Zhiming Chen;Zhicheng Hu;Zhihong Wu;Xiang Liu;Yaocheng Jin;Manjun Xiao;Yong Cao
Journal of Materials Chemistry A 2017 vol. 5(Issue 36) pp:19447-19455
Publication Date(Web):2017/09/19
DOI:10.1039/C7TA05246D
N-type conjugated polyelectrolytes (CPEs) are promising electron transport materials (ETMs) in high-performance polymer solar cells (PSCs). The regulation of the counterions of CPEs can efficiently tune the properties of CPEs as well as their photovoltaic performance. In this contribution, we report a series of counterion-tunable n-type CPEs for the interface engineering of polymer solar cells, and the size, species and substituent groups of the counterions are discussed. The size of counterions had a great impact on the alcohol solubility and photophysical properties of CPEs. Besides, the self-doping behaviors of these CPEs are also highly correlated with their counterion species. Moreover, the charge transport and electrode modification study results show that the counterion species and their substituent groups are critical to the electron mobilities and electrode modification ability of these CPEs as well as their performance in PSCs. PSCs with these CPEs as ETMs can deliver high power conversion efficiency (PCE) up to 10.5%, and over 9.5% PCE can be maintained even when these CPEs are used as thick (80 nm) ETMs, indicating great potential of using these CPEs as thickness-insensitive ETMs for the fabrication of future large-area PSCs using roll-to-roll techniques.
Co-reporter:Chen Sun;Zhihong Wu;Zhanhao Hu;Jingyang Xiao;Wenchao Zhao;Ho-Wa Li;Qing-Ya Li;Sai-Wing Tsang;Yun-Xiang Xu;Kai Zhang;Hin-Lap Yip;Jianhui Hou;Yong Cao
Energy & Environmental Science (2008-Present) 2017 vol. 10(Issue 8) pp:1784-1791
Publication Date(Web):2017/08/09
DOI:10.1039/C7EE00601B
Non-fullerene polymer solar cells have attracted extensive attention due to their potential for overcoming the performance bottleneck currently encountered in fullerene-based photovoltaics. Herein, we report non-fullerene polymer solar cells with a maximal power conversion efficiency of over 11% by introducing an n-type water/alcohol soluble conjugated polymer as a cathode interlayer. We found that the contact between the n-type interlayer and the donor provides an extra interface for charge dissociation and the matching of energy levels between the n-type interlayer and the acceptor allows efficient electron extraction from the bulk heterojunction, which eventually leads to much improved performance. This study proposes a significant design rule for designing new interfaces for high performance non-fullerene photovoltaics.
Co-reporter:Yunping Huang;Nannan Zheng;Zhenfeng Wang;Lei Ying;Yong Cao
Chemical Communications 2017 vol. 53(Issue 12) pp:1997-2000
Publication Date(Web):2017/02/07
DOI:10.1039/C6CC09317E
Regioregular polymers based on an asymmetric dithieno[3,2-b:2′,3′-d]pyridin-5(4H)-one (TN) unit that consists of a lactam moiety were synthesized via palladium-catalyzed direct heteroarylation polymerization. The random orientation of the lactam moiety can be prevented by carefully designing the monomers with tailored molecular structures. It is noted that connecting the TN unit in different fashions generates substructures in the polymer backbone with different electronic structures. Compared to the random counterparts, the regioregular homopolymers exhibit dramatically discrepant optical properties and electronic structures, while the variations in the copolymers are less distinguished.
Co-reporter:Zhicheng Hu;Lei Ying;Yong Cao
Science China Chemistry 2017 Volume 60( Issue 5) pp:571-582
Publication Date(Web):01 March 2017
DOI:10.1007/s11426-016-0424-9
Remarkable progress in high-performance polymer solar cells demonstrates their great potential for practical applications in the near future. Indeed, the power conversion efficiencies over 10% have been reported by many research groups, which are achieved through rational optimization of light-harvesting materials, interfaces and device processing technologies. In this mini review, we summarized the recent progress of highly efficient polymer solar cells, with specifically concern on successful strategies of rational molecular design of electron-donating and electron-accepting materials, elaborative interfacial engineering, and reasonable device architectures.
Co-reporter:Jianchao Jia;Nannan Zheng;Zhenfeng Wang;Yunping Huang
Science China Chemistry 2017 Volume 60( Issue 11) pp:1458-1467
Publication Date(Web):08 September 2017
DOI:10.1007/s11426-017-9102-1
A series of novel wide bandgap small molecules (IFT-ECA, IFT-M, IFT-TH and IFT-IC) based on the A-D-A structure with indenofluorene core, thiophene bridge, and different electron-deficient end-capping groups, were synthesized and used as non-fullerene acceptors in organic solar cells. The influences of end-capping groups on the device performance were studied. The four materials exhibited different physical and chemical properties due to the variation of end-capping groups, which further affect the exciton dissociation, charge transport, morphology of the bulk-heterojunction films and device performance. Among them, IFT-IC-based device delivered the best power conversion efficiency of 7.16% due to proper nano-scale phase separation morphology and high electron mobility, while the devices based on the other acceptors achieved lower device performance (4.14% for IFT-TH, <1% for IFT-ECA and IFT-M). Our results indicate the importance of choosing suitable electron-withdrawing groups to construct high-performance non-fullerene acceptors based on A-D-A motif.
Co-reporter:Aihui Liang, Jun Tang, Ping Cai, Xiulan Yang, Wenjin Wu, Ling Chen, Zhiping Wang, Mingzhong Cai, Fei Huang
Dyes and Pigments 2017 Volume 138(Volume 138) pp:
Publication Date(Web):1 March 2017
DOI:10.1016/j.dyepig.2016.11.032
•Sky-blue OLEDs with dibenzo-24-crown-8 substituted iridium complexes were fabricated.•The CIE coordinates of Bn are maintained at about (0.18, 0.42) vary from 6% to 14%.•The solution-processed devices with a highest LE of 10.7 cd A−1 were achieved.We report several sky-blue phosphorescent organic light-emitting diodes (PhOLEDs) fabricated by spin-coating technique, using dibenzo-24-crown-8 unit-based iridium complexes (B1, B2 and B3) as the dopants and poly(N-vinylcarbazole) (PVK) as the polymer host. Among these, the single emissive layer PhOLEDs from B3 exhibited the best electroluminescent performances with a maximum luminous efficiency (LEmax) of 10.7 cd A−1 at a current density of 4.6 mA cm−2 and a maximum brightness (Lmax) of 4604 cd m−2. Compared to B1 and B3, the devices with B2 as dopant displayed much lower device's performances (LEmax = 4.2 cd A−1 and Lmax = 1433 cd m−2) as the presence of p-terphenyl unit in the auxiliary ligand of B2, the triplet energy level of which is slightly less than that of iridium (III) bis[(4,6-difluorophenyl)pyridinato-N,C2′] picolinate (FIrpic). This present work demonstrates that the triplet energy level of the cyclometalated and/or auxiliary ligands of the iridium complexes should be considered to design novel electrophosphorescent materials for highly efficient PhOLEDs.Several sky-blue phosphorescent organic light-emitting diodes (PhOLEDs) were fabricated by spin-coating technique, using dibenzo-24-crown-8 unit-based iridium complexes (B1, B2 and B3) as the dopants and poly(N-vinylcarbazole) (PVK) as the polymer host. The PhOLEDs based on B3 exhibited the best electroluminescent performances with a maximum luminous efficiency of 10.7 cd A−1 and a maximum brightness of 4604 cd m−2.Download high-res image (286KB)Download full-size image
Co-reporter:Zhenfeng Wang;Nannan Zheng;Wenqiang Zhang;He Yan;Zengqi Xie;Yuguang Ma;Yong Cao
Advanced Energy Materials 2017 Volume 7(Issue 15) pp:
Publication Date(Web):2017/08/01
DOI:10.1002/aenm.201700232
Perylene diimide (PDI) with high electron affinities are promising candidates for applications in polymer solar cells (PSCs). In addition, the strength of π-deficient backbones and end-groups in an n-type self-dopable system strongly affects the formed end-group-induced electronic interactions. Herein, a series of amine/ammonium functionalized PDIs with excellent alcohol solubility are synthesized and employed as electron transporting layers (ETLs) in PSCs. The electron transfer properties of the resulting PDIs are dramatically tuned by different end-groups and π-deficient backbones. Notably, electron transfer is observed directly in solution in self-doped PDIs for the first time. A significantly enhanced power conversion efficiency of 10.06% is achieved, when applying the PDIs as ETLs in PTB7-Th:PC71BM-based PSCs. These results demonstrate the potential of n-type organic semiconductors with stable n-type doping capability and facile solution processibility for future applications of energy transition devices.
Co-reporter:Sheng Dong;Zhicheng Hu;Kai Zhang;Qingwu Yin;Xiaofang Jiang;Yong Cao
Advanced Materials 2017 Volume 29(Issue 34) pp:
Publication Date(Web):2017/09/01
DOI:10.1002/adma.201701507
A cross-linkable dual functional polymer hybrid electron transport layer (ETL) is developed by simply adding an amino-functionalized polymer dopant (PN4N) and a light crosslinker into a commercialized n-type semiconductor (N2200) matrix. It is found that the resulting hybrid ETL not only has a good solvent resistance, facilitating multilayers device fabrication but also exhibits much improved electron transporting/extraction properties due to the doping between PN4N and N2200. As a result, by using PTB7-Th:PC71BM blend as an active layer, the inverted device based on the hybrid ETL can yield a prominent power conversion efficiency of around 10.07%. More interestingly, photovoltaic property studies of bilayer devices suggest that the absorption of the hybrid ETL contributes to photocurrent and hence the hybrid ETL simultaneously acts as both cathode interlayer material and an electron acceptor. The resulting inverted polymer solar cells function like a novel device architectures with a combination of a bulk heterojunction device and miniature bilayer devices. This work provides new insights on function of ETLs and may be open up a new direction for the design of new ETL materials and novel device architectures to further improve device performance.
Co-reporter:Kai Zhang;Ke Gao;Ruoxi Xia;Zhihong Wu;Chen Sun;Jiamin Cao;Liu Qian;Weiqi Li;Shiyuan Liu;Xiaobin Peng;Liming Ding;Hin-Lap Yip;Yong Cao
Advanced Materials 2016 Volume 28( Issue 24) pp:4817-4823
Publication Date(Web):
DOI:10.1002/adma.201506270
Co-reporter:Chen Sun;Zhihong Wu;Hin-Lap Yip;Hua Zhang;Xiao-Fang Jiang;Qifan Xue;Zhicheng Hu;Zhanhao Hu;Yan Shen;Mingkui Wang;Yong Cao
Advanced Energy Materials 2016 Volume 6( Issue 5) pp:
Publication Date(Web):
DOI:10.1002/aenm.201501534
An amino-functionalized copolymer with a conjugated backbone composed of fluorene, naphthalene diimide, and thiophene spacers (PFN-2TNDI) is introduced as an alternative electron transport layer (ETL) to replace the commonly used [6,6]-Phenyl-C61-butyric acid methyl ester (PCBM) in the p–i–n planar-heterojunction organometal trihalide perovskite solar cells. A combination of characterizations including photoluminescence (PL), time-resolved PL decay, Kelvin probe measurement, and impedance spectroscopy is used to study the interfacial effects induced by the new ETL. It is found that the amines on the polymer side chains not only can passivate the surface traps of perovskite to improve the electron extraction properties, they also can reduce the work function of the metal cathode by forming desired interfacial dipoles. With these dual functionalities, the resulted solar cells outperform those based on PCBM with power conversion efficiency (PCE) increased from 12.9% to 16.7% based on PFN-2TNDI. In addition to the performance enhancement, it is also found that a wide range of thicknesses of the new ETL can be applied to produce high PCE devices owing to the good electron transport property of the polymer, which offers a better processing window for potential fabrication of perovskite solar cells using large-area coating method.
Co-reporter:Jing Wang;Kai Lin;Kai Zhang;Xiao-Fang Jiang;Khalid Mahmood;Lei Ying;Yong Cao
Advanced Energy Materials 2016 Volume 6( Issue 11) pp:
Publication Date(Web):
DOI:10.1002/aenm.201502563
A novel crosslinkable aminoalkyl-functionalized polymer, poly[9,9-bis(6-(N,N-diethylamino)propyl)fluorene-alt-9,9-bis(hex-5-en-1-yl)-fluorene] (PFN-V), is designed and synthesized. The resulting polymer can be rapidly crosslinked by UV-curing within 5 s in a nearly quantitative yield based on the “click” chemistry of alkyene end-groups of the PFN-V side chains and the addition of 1,8-octanedithiol. The crosslinked PFN-V film exhibits excellent solvent resistance property and can act as effective cathode interlayer to modify the indium tin oxide (ITO) electrode, which can thus facilitate the formation of Ohmic contact between cathode and active layer. The surface energy of PFN-V is quite comparable to that of PC71BM, which is favorable for the formation of vertical phase separation in the bulk heterojunction film that can facilitate extraction of charges as verified by transient photocurrent measurements. Based on the resulting PFN-V as the cathode interlayer, the fabricated polymer solar cells with inverted device structure show a remarkable enhancement of power conversion efficiency from 3.11% for the control device to 9.18% for PFN-V based device. These observations indicate that the synthesized PFN-V can be a promising crosslinked copolymer as the cathode interlayer for high performance polymer solar cells.
Co-reporter:Zhihong Wu; Chen Sun; Sheng Dong; Xiao-Fang Jiang; Siping Wu; Hongbin Wu; Hin-Lap Yip; Fei Huang;Yong Cao
Journal of the American Chemical Society 2016 Volume 138(Issue 6) pp:2004-2013
Publication Date(Web):January 22, 2016
DOI:10.1021/jacs.5b12664
With the demonstration of small-area, single-junction polymer solar cells (PSCs) with power conversion efficiencies (PCEs) over the 10% performance milestone, the manufacturing of high-performance large-area PSC modules is becoming the most critical issue for commercial applications. However, materials and processes that are optimized for fabricating small-area devices may not be applicable for the production of high-performance large-area PSC modules. One of the challenges is to develop new conductive interfacial materials that can be easily processed with a wide range of thicknesses without significantly affecting the performance of the PSCs. Toward this goal, we report two novel naphthalene diimide-based, self-doped, n-type water/alcohol-soluble conjugated polymers (WSCPs) that can be processed with a broad thickness range of 5 to 100 nm as efficient electron transporting layers (ETLs) for high-performance PSCs. Space charge limited current and electron spin resonance spectroscopy studies confirm that the presence of amine or ammonium bromide groups on the side chains of the WSCP can n-dope PC71BM at the bulk heterojunction (BHJ)/ETL interface, which improves the electron extraction properties at the cathode. In addition, both amino functional groups can induce self-doping to the WSCPs, although by different doping mechanisms, which leads to highly conductive ETLs with reduced ohmic loss for electron transport and extraction. Ultimately, PSCs based on the self-doped WSCP ETLs exhibit significantly improved device performance, yielding PCEs as high as 9.7% and 10.11% for PTB7-Th/PC71BM and PffBT4T-2OD/PC71BM systems, respectively. More importantly, with PffBT4T-2OD/PC71BM BHJ as an active layer, a prominent PCE of over 8% was achieved even when a thick ETL of 100 nm was used. To the best of our knowledge, this is the highest efficiency demonstrated for PSCs with a thick interlayer and light-harvesting layer, which are important criteria for eventually making organic photovoltaic modules based on roll-to-roll coating processes.
Co-reporter:Aihui Liang, Gui Huang, Sheng Dong, Xiaoyan Zheng, Jia Zhu, Zhiping Wang, Wenjin Wu, Jie Zhang and Fei Huang
Journal of Materials Chemistry A 2016 vol. 4(Issue 27) pp:6626-6633
Publication Date(Web):13 Jun 2016
DOI:10.1039/C6TC01922F
We have designed two novel yellow phosphorescent iridium complexes with triphenylamine- and fluorene-functionalized cyclometalating ligands that are capable of producing highly efficient yellow and white polymer light-emitting devices (PLEDs). Both yellow and white-light-emission devices are achieved with an identical single-emission-layer configuration of ITO/PEDOT:PSS/emission layer (EML)/CsF/Al. For the yellow phosphorescent PLEDs based on Y1, the best device performances with a peak luminous efficiency (LE) of 15.1 cd A−1 and a peak external quantum efficiency (EQE) of 7.6% are achieved. More importantly, the two-emitting-component WPLEDs containing iridum(III)bis(2-(4,6-difluorophenyl)-pyridinato-N,C2′) picolinate (FIrpic) as blue and Y1 as yellow phosphors doped into a PVK:OXD-7 matrix at an appropriate ratio exhibited a maximum LE of 14.7 cd A−1, a maximum EQE of 8.6%, a maximum luminance of 5586 cd m−2 and Commission Internationale de L'Eclairage (CIE) coordinates of (0.33, 0.42) which are close to the standard for white light emission. Moreover, at a luminance for practical application of 1000 cd m−2, a good forward viewing LE of 14.4 cd A−1 is obtained with a very slight decrease.
Co-reporter:Wenzhan Xu, Yongtao Liu, Xiaojuan Huang, Lili Jiang, Qingduan Li, Xiaowen Hu, Fei Huang, Xiong Gong and Yong Cao
Journal of Materials Chemistry A 2016 vol. 4(Issue 10) pp:1953-1958
Publication Date(Web):05 Feb 2016
DOI:10.1039/C6TC00109B
In this study, we report solution-processed vanadium oxide (s-VOx) as the hole extraction layer (HEL) for polymer solar cells (PSCs). A s-VOx thin film is prepared simply by the spin-coating of ammonium metavanadate ammonal water solution on the surface of indium tin oxide (ITO) coated glass substrates, followed by thermal annealing at 210 °C for 5 minutes in air. The scanning Kelvin probe measurement indicates that the work function of the s-VOx HEL is −5.3 eV, which allows most of the conjugated polymers to form an Ohmic contact with the s-VOx HEL, resulting in a large open-circuit voltage for PSCs. It is found that PSCs incorporated with the s-VOx HEL possess a comparable power conversion efficiency and better shelf-stability with those incorporated with the poly (3,4-ethylenedioxythiophene):poly-(styrenesulfonate) anode buffer layer. Thus, our method provides a simple approach to prepare a solution-processed s-VOx HEL for higher performance PSCs.
Co-reporter:Jing Yue, Sheng Sun, Junfei Liang, Wenkai Zhong, Linfeng Lan, Lei Ying, Fei Huang, Wei Yang and Yong Cao
Journal of Materials Chemistry A 2016 vol. 4(Issue 13) pp:2470-2479
Publication Date(Web):15 Feb 2016
DOI:10.1039/C6TC00051G
Two novel regio-isomeric π-conjugated polymers consisting of the pyridyl unit flanked by diketopyrrolopyrrole as the electron-accepting unit and 2,5-bis(3-hexylthiophen-2-yl)thieno[3,2-b]thiophene as the electron-donating unit were designed and synthesized. The comparison of the optical and electrochemical properties indicated that the copolymer based on the nitrogen atom proximal to the central diketopyrrolopyrrole unit (p-PDBPy) exhibited bathochromic shifted absorption spectra and narrower bandgaps than the counterpart copolymer (d-PDBPy) with the distally oriented nitrogen atom, which can be correlated with the stronger intermolecular aggregation of the former as a result of the different intrinsic molecular geometry of the polymer backbone. Of particular interest is that the copolymer p-PDBPy exhibited a moderate hole mobility of 0.35 cm2 V−1 s−1, which is about three orders of magnitude higher than the hole mobility of 3.2 × 10−4 cm2 V−1 s−1 obtained based on the counterpart copolymer d-PDBPy, as measured using organic field-effect transistors. These results demonstrated that the delicate control of the pyridyl orientations along the polymer backbone is of vital importance for the molecular design of π-conjugated polymers for high-performance organic electronic devices.
Co-reporter:Xi Liu, Rongguo Xu, Chunhui Duan, Fei Huang and Yong Cao
Journal of Materials Chemistry A 2016 vol. 4(Issue 19) pp:4288-4295
Publication Date(Web):07 Apr 2016
DOI:10.1039/C6TC00906A
A series of non-conjugated water/alcohol soluble copolymers containing diphenyl sulfide, diphenyl sulfoxide or diphenyl sulfone in the main chain were synthesized. The surfactant-like functionalities in side chains endow the polymers with outstanding solubility in highly polar solvents and excellent electron extraction abilities, while the limited conjugation length of main chains renders the polymers weak optical absorption. These unique characteristics make the polymers excellent cathode interfacial layers, which contribute to highly efficient polymer solar cells (PSCs) with power conversion efficiencies of 8–9%. More importantly, some of them can yield highly efficient PSCs in a relative large interlayer thickness range of 2–20 nm. The results suggest that these polymers are promising candidates for use as cathode interfacial layers in single-junction PSCs and as recombination layers in multi-junction PSCs.
Co-reporter:Wenkai Zhong, Jingyang Xiao, Sheng Sun, Xiao-Fang Jiang, Linfeng Lan, Lei Ying, Wei Yang, Hin-Lap Yip, Fei Huang and Yong Cao
Journal of Materials Chemistry A 2016 vol. 4(Issue 21) pp:4719-4727
Publication Date(Web):11 Apr 2016
DOI:10.1039/C6TC00271D
Two wide bandgap donor–acceptor type π-conjugated polymers based on dithienobenzodithiophene as the donor unit and difluorobenzotriazole or difluorobenzothiadiazole as the acceptor unit were designed and synthesized. The copolymer based on difluorobenzothiadiazole exhibited more pronounced aggregations in chlorobenzene solutions than that of the copolymer based on difluorobenzotriazole. Both copolymers exhibited relatively wide bandgaps with deep highest occupied molecular orbitals, leading to high open circuit voltages of over 0.95 V for the fabricated polymer solar cells. These copolymers exhibited quite analogous hole mobility of about 0.1 cm2 V−1 s−1 as measured by organic field effect transistors. Bulk heterojunction polymer solar cells based on these copolymers as the electron-donating materials and PC71BM as the electron-accepting material exhibited relatively high performance, with the best power conversion efficiency of 7.45% attained for the copolymer based on the difluorobenzothiadiazole unit. These results demonstrated that the constructed wide bandgap π-conjugated polymers can be promising candidates for the fabrication of high performance solar cells with multi-junction architectures.
Co-reporter:Junfei Liang, Sen Zhao, Xiao-Fang Jiang, Ting Guo, Hin-Lap Yip, Lei Ying, Fei Huang, Wei Yang, and Yong Cao
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 9) pp:6164
Publication Date(Web):February 17, 2016
DOI:10.1021/acsami.5b11926
In this Article, we designed and synthesized a series of polyfluorene derivatives, which consist of the electron-rich 4,4′-(9-alkyl-carbazole-3,6-diyl)bis(N,N-diphenylaniline) (TPA-Cz) in the side chain and the electron-deficient dibenzothiophene-5,5-dioxide (SO) unit in the main chain. The resulting copolymer PF-T25 that did not comprise the SO unit exhibited blue light-emission with the Commission Internationale de L’Eclairage coordinates of (0.16, 0.10). However, by physically blending PF-T25 with a blue light-emitting SO-based oligomer, a novel low-energy emission correlated to exciplex emerged due to the appropriate energy level alignment of TPA-Cz and the SO-based oligomers, which showed extended exciton lifetime as confirmed by time-resolved photoluminescent spectroscopy. The low-energy emission was also identified in copolymers consisting of SO unit in the main chain, which can effectively compensate for the high-energy emission to produce binary white light-emission. Polymer light-emitting diodes based on the exciplex-type single greenish-white polymer exhibit the peak luminous efficiency of 2.34 cd A–1 and the maximum brightness of 12 410 cd m–2, with Commission Internationale de L’Eclairage color coordinates (0.27, 0.39). The device based on such polymer showed much better electroluminescent stability than those based on blending films. These observations indicated that developing a single polymer with the generated exciplex emission can be a novel and effective molecular design strategy toward highly stable and efficient white polymer light-emitting diodes.Keywords: exciplex; highly stable electroluminescence; polymer light-emitting diodes; solution process; white light-emitting;
Co-reporter:Chunchen Liu, Wenzhan Xu, Qifan Xue, Ping Cai, Lei Ying, Fei Huang, Yong Cao
Dyes and Pigments 2016 Volume 125() pp:54-63
Publication Date(Web):February 2016
DOI:10.1016/j.dyepig.2015.10.003
•Indigo and isoindigo-based molecules with removable substituents were developed.•The substituents can be thermally removed at about 190 °C.•Molecular coplanarity can be significantly improved after removal of substituents.•One-dimensional nanowires were obtained via hydrogen bond assisted self-assembly.•These nanowires exhibited impressive charge transport property.In this manuscript, indigo and isoindigo-based π-conjugated molecules with thermal removable tert-butoxycarbonyl (t-Boc) side groups were designed and synthesized. It was noted that the t-Boc side groups can be eliminated in nearly quantitative yields after thermal treatment at 200 °C for 15 min, as confirmed by thermogravimetric analysis and Fourier transform infrared spectroscopy. From the thermal treated solution of isoindigo-based molecule DTIIC8C12 in the co-solvent of 1,2-dichlorobenzene/pyridine with volume ratio of 10/90, one-dimensional nanowires can be formed due to the hydrogen bonding assisted self-assembly. The afforded nanowires exhibited a moderate hole mobility of 1.3 × 10−3 cm2 V−1 s−1, as estimated from the organic field effect transistors. These observations illustrated that the utilization of thermal removable side chain functionalized conjugated polymers can be an effective strategy for developing conjugated polymers with impressive charge carrier transport.
Co-reporter:Ruihao Xie, Zhiming Chen, Wenkai Zhong, Guichuan Zhang, Yunping Huang, Lei Ying, Fei Huang and Yong Cao
New Journal of Chemistry 2016 vol. 40(Issue 5) pp:4727-4734
Publication Date(Web):15 Mar 2016
DOI:10.1039/C5NJ03174E
A series of novel electron-donating building blocks of alkyltriazolyl substituted benzodithiophene were synthesized on the basis of Cu(I)-catalyzed azide–alkyne cycloaddition. The alternating donor–acceptor type of π-conjugated copolymers by using such alkyltriazolyl substituted benzodithiophene as donor units and diketopyrrolopyrrole as acceptor units were synthesized via Suzuki polymerization. The resultant copolymers exhibited good thermal properties and can be easily dissolved in various organic solvents. All copolymers show quite comparable absorption profiles in the range of 300–850 nm with the absorption onset at about 1.4 eV, where the copolymer with longer side chains exhibited a slightly enhanced absorption coefficient. The cyclic voltammetry measurements indicated the highest occupied molecular orbitals and the lowest unoccupied molecular orbitals located at about −5.40 and −3.40 eV, respectively, which were nearly independent of the size of alkyl side chains. Polymer solar cells based on the resultant copolymers as electron-donating materials and PC71BM as the electron-accepting material exhibited moderate photovoltaic performances.
Co-reporter:Yunping Huang;Wenzhan Xu;Cheng Zhou;Wenkai Zhong;Ruihao Xie;Xiong Gong;Lei Ying;Yong Cao
Journal of Polymer Science Part A: Polymer Chemistry 2016 Volume 54( Issue 14) pp:2119-2127
Publication Date(Web):
DOI:10.1002/pola.28079
ABSTRACT
Two novel dibromo monomers consisting of the isomers of 5-alkylphenanthridin-6(5H)-one (PN) and 6-alkoxylphenanthridine (PO) were synthesized through alkylation of the precursor 3,8-dibromophenanthrindi-6(5H)-one, where the molecular structures were confirmed by NMR spectroscopy. The medium bandgap conjugated polymers PDBTPN and PDBTPO were constructed by utilizing such two isomers PN and PO as the electron-donating units and dithiophenebenzo[2,1,3]diathiazole as the electron-accepting unit. The resulting polymers exhibited analogous absorption profiles with optical bandgap of 1.90 eV, while PDBTPO showed slightly higher absorption coefficiency. Cyclic voltammetry measurements revealed that these polymers had relatively deep highest occupied molecular orbital levels of about −5.70 eV. Polymer solar cells based on such two polymers showed relatively high open-circuit voltage of about 0.90 V. All devices exhibited moderate performances with the best power conversion efficiency of 3.77% achieved based on PDBTPO. Devices based on PDBTPO showed slightly higher power conversion efficiency than those based on PDBTPN, which can be ascribed to higher hole mobility and more favorable film morphology of the former. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 2119–2127
Co-reporter:Wenkai Zhong, Junfei Liang, Shuzhi Hu, Xiao-Fang Jiang, Lei Ying, Fei Huang, Wei Yang, and Yong Cao
Macromolecules 2016 Volume 49(Issue 16) pp:5806-5816
Publication Date(Web):August 2, 2016
DOI:10.1021/acs.macromol.6b00185
The effects of fluorine substitutions on the molecular geometry and optoelectronic properties were investigated based on the conjugated molecular framework consisting of the mono-fluorinated benzo[c][1,2,5]thiadiazole unit. The two-dimensional nuclear magnetic resonance spectroscopy of model compounds indicated that the fluorine substitution can significantly change the chemical environment of the adjacent hydrogen atoms, which was in consistence with the changed molecular geometry as indicated by single crystal diffractions and theoretical calculations. Based on an AB type of monomer, the regioregular conjugated polymer with specifically oriented fluorine along the vector of the polymer backbone was constructed. The UV–vis absorption, photoluminescent, and electroluminescent spectra demonstrated the slightly hypsochromic shift of the copolymer comprising the fluorine substitution relative to the non-fluorinated counterpart. Of particular interest is that the copolymer based on the fluorinated benzothiadiazole unit exhibited electron-dominant charge transportation, for which the electron mobility is about 1 order of magnitude higher than that of hole mobility.
Co-reporter:Yue Xing, Chen Sun, Hin.-Lap. Yip, Guillermo C. Bazan, Fei Huang, Yong Cao
Nano Energy 2016 Volume 26() pp:7-15
Publication Date(Web):August 2016
DOI:10.1016/j.nanoen.2016.04.057
•A new series of hydrophilic fullerene derivatives was introduced as ETLs in PVKSCs.•OE chains could passivate trap states of perovskite and reduce the WF of cathode.•A full analysis using controlled electron density in passivators was demonstrated.•The underlying mechanism of trap passivation was better understood in this work.•A high PCE of 16.0% has been achieved.Defect states within perovskite crystals are thought to induce undesired charge recombination and photocurrent hysteresis in perovskite solar cells. Although the processing of perovskite films with electron-rich molecules that can efficiently passivate the surface traps, the exact mechanism remains unclear. As the electron-rich units are key components for such a function, a rigorous analysis using controlled electron density in passivators can provide the means to understand these underlying mechanisms and thereby improve future improvements. In the study reported here, we combined electron-rich functional groups with fullerenes to design a new series of hydrophilic fullerene derivatives, in which each phenyl group of the diphenylmethanofullerene (DPM) moiety was decorated with an oligoether (OE) side group. These new materials were introduced as alternative electron transport layers (ETLs) to replace the commonly used PCBM in p-i-n planar-heterojunction perovskite solar cells. Our tests indicate that electron-rich OE chains can both passivate perovskite trap states and reduce the work function of the metal cathode. By adjusting the numbers of OE chains, relevant properties such as the energy levels, charge carrier mobilities, surface energy and dipole layer features could be tuned at the interfaces. Furthermore, devices with these fullerene ETLs showed significant improvements in power conversion efficiency (PCE) compared to devices with PCBM ETLs. A high PCE of 16% was achieved by applying the monoadduct fullerene derivative C70-DPM-OE as the ETL of the device.
Co-reporter:Zhihong Wu;Yongxiang Zhu;Wei Li;Yunping Huang;Junwu Chen
Science China Chemistry 2016 Volume 59( Issue 12) pp:1583-1592
Publication Date(Web):2016 December
DOI:10.1007/s11426-016-0203-5
A series of novel acceptor-pended conjugated polymers featuring a newly developed carbazole-derived unit are designed and synthesized. The relationships between chemical structure and optoelectronic properties of the polymers are systematically investigated. The control of UV-Vis absorption spectra and energy levels in resulting polymers are achieved by introducing suitable pended acceptor units. The photovoltaic properties of the resulting polymers are evaluated by blending the polymers with (6,6)-phenyl-C71-butyric acid methyl ester. The resulting solar cells exhibit moderate performances with high open-circuit voltage. Charge transport properties and morphology were investigated to understand the performance of corresponding solar cells.
Co-reporter:Kai Zhang;Zhicheng Hu;Rongguo Xu;Xiao-Fang Jiang;Hin-Lap Yip;Yong Cao
Advanced Materials 2015 Volume 27( Issue 24) pp:3607-3613
Publication Date(Web):
DOI:10.1002/adma.201500972
Co-reporter:Shunmian Lu;Xing Guan;Xinchen Li;Wei E. I. Sha;Fengxian Xie;Hongchao Liu;Jiannong Wang;Wallace C. H. Choy
Advanced Energy Materials 2015 Volume 5( Issue 17) pp:
Publication Date(Web):
DOI:10.1002/aenm.201500631
A new metal-oxide-based interconnecting layer (ICL) structure of all-solution processed metal oxide/dipole layer/metal oxide for efficient tandem organic solar cell (OSC) is demonstrated. The dipole layer modifies the work function (WF) of molybdenum oxide (MoO x ) to eliminate preexisted counter diode between MoO x and TiO2. Three different amino functionalized water/alcohol soluble conjugated polymers (WSCPs) are studied to show that the WF tuning of MoO x is controllable. Importantly, the results show that S-shape current density versus voltage (J–V) characteristics form when operation temperature decreases. This implies that thermionic emission within the dipole layer plays critical role for helping recombination of electrons and holes. Meanwhile, the insignificant homotandem open-circuit voltage (V oc) loss dependence on dipole layer thickness shows that the quantum tunneling effect is weak for efficient electron and hole recombination. Based on this ICL, poly(3-hexylthiophene) (P3HT)-based homotandem OSC with 1.20 V V oc and 3.29% power conversion efficiency (PCE) is achieved. Furthermore, high efficiency poly(4,8-bis(5-(2-ethylhexyl)-thiophene-2-yl)-benzo[1,2-b54,5-b9]dithiophene-alt alkylcarbonylthieno[3,4-b]thiophene) (PBDTTT-C-T)-based homotandem OSC with 1.54 V V oc and 8.11% PCE is achieved, with almost 15.53% enhancement compared to its single cell. This metal oxide/dipole layer/metal oxide ICL provides a new strategy to develop other qualified ICL with different hole transporting layer and electron transporting layer in tandem OSCs.
Co-reporter:Peng Liu;Sheng Dong;Feng Liu;Xiaowen Hu;Liqian Liu;Yaocheng Jin;Shengjian Liu;Xiong Gong;Thomas P. Russell;Yong Cao
Advanced Functional Materials 2015 Volume 25( Issue 41) pp:6458-6469
Publication Date(Web):
DOI:10.1002/adfm.201501878
A series of conjugated polymers using naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole and benzodithiophene alternating backbone is synthesized to investigate the effect of side chain substitution on conjugated donor–acceptor polymer on electronic, morphological, and photovoltaic properties. It is found that light absorption and frontier energy levels of the resultant polymers are strongly affected by the side chains. The thin film morphology, crystal structure, crystallinity, and orientation also depend on the side chains; the side chain type affects more in the π–π stacking direction, while the side chain density plays a significant role in the lamellar packing direction. The thickness of the active layer also influences the performance of the solar cells with some materials showing enhanced performance with thicker active layers. The best solar cell device in this study has power conversion efficiencies of 8.14%, among the highest in materials of similar structure.
Co-reporter:Zuosheng Peng, Yangdong Zhang, Yuxin Xia, Kang Xiong, Chaosheng Cai, Lianpeng Xia, Zhanhao Hu, Kai Zhang, Fei Huang and Lintao Hou
Journal of Materials Chemistry A 2015 vol. 3(Issue 41) pp:20500-20507
Publication Date(Web):03 Sep 2015
DOI:10.1039/C5TA06009E
We report a facile technique of blending a conjugated polymer thieno[3,4-b]thiophene/benzodithiophene (PTB7):[6,6]-phenyl-C71-butyric acid methyl ester (PCBM[70]) active materials with a conjugated interfacial modification polymer poly[(9,9-bis(3′-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) to simplify the coating process and improve the bulk heterojunction (BHJ) polymer solar cell (PSC) performance. The reason for and result of PFN self-organization via a spontaneous vertical delamination onto the ITO surface were investigated by charge transfer state, optical modelling based on transfer matrix formalism, surface energy measurement, scanning Kelvin probe force microscopy and impedance spectroscopy analysis in conjunction with atomic force microscopy and scanning electron microscopy. The relaxed charge transfer state demonstrates that PFN doping has a negligible impact on the donor:acceptor heterojunction interface. The optical simulation of device structures indicates that doping PFN into a BHJ has nearly no influence on the photon absorption profile of the active layer. Very encouraging device performance was achieved in the one-step coating PFN:BHJ PSC with ITO as the cathode, which is comparable to that of the two-step coating PSC. Moreover, for ITO-free inverted PSCs with PEDOT:PSS as the incident light top-electrode, decent device performance can also be obtained, demonstrating the remarkable universality through this facile strategy.
Co-reporter:Qin Hu, Yi Liu, Yu Li, Lei Ying, Tanghao Liu, Fei Huang, Shufeng Wang, Wei Huang, Rui Zhu and Qihuang Gong
Journal of Materials Chemistry A 2015 vol. 3(Issue 36) pp:18483-18491
Publication Date(Web):04 Aug 2015
DOI:10.1039/C5TA04695E
A cross-linkable conjugated polymer, poly[9,9-bis(6′-(N,N-diethylamino)propyl)-fluorene-alt-9,9-bis-(3-ethyl(oxetane-3-ethyloxy)-hexyl)-fluorene] (PFN-OX), was investigated as the n-type interface layer for highly efficient and low-temperature processed planar heterojunction perovskite solar cells. Hybrid composite films consisting of PFN-OX and ZnO nanoparticles were utilized as electron selective layers, and a remarkable power conversion efficiency over 16% was achieved. The cross-linkable PFN-OX provided a robust hybrid composite electron selective layer, which is solvent-resistant during the device fabrication process and results in efficient electron extraction and hole blocking. Meanwhile, time-resolved photoluminescence quenching measurements indicated that the charge separation and collection processes were improved for devices based on PFN-OX:ZnO, in comparison with devices using pure PFN-OX or ZnO. The device stability and the hysteresis effect were also discussed. Moreover, this study introduces the cross-linking concept in perovskite solar cells, which will potentially be an effective strategy for obtaining high performance perovskite solar cells.
Co-reporter:Shengjian Liu, Guichuan Zhang, Junming Lu, Jianchao Jia, Wei Li, Fei Huang and Yong Cao
Journal of Materials Chemistry A 2015 vol. 3(Issue 17) pp:4372-4379
Publication Date(Web):24 Mar 2015
DOI:10.1039/C5TC00452G
A small-molecule amino-functionalized organoplatinum(II) complex Pt–N has been developed. The unique properties of Pt–N, including a well-defined chemical structure, an excellent solubility in environmentally friendly polar solvents and good electron extraction to high work-function metals, make it a promising candidate for cathode interfacial modification of solution processed multilayer polymer solar cells (PSCs). The resultant PSCs with an ITO/PEDOT:PSS/PTB7:PC71BM/interlayer/Al device configuration exhibited significantly improved efficiencies from 3.62% for an unmodified device to 8.89% by using a Pt–N cathode interlayer, benefiting from the dramatic enhancement in the open circuit voltage (0.53 V for bare Al PSCs to 0.75 V for Pt–N/Al PSCs), the fill factor (43.58% for bare Al PSC to 72.49% for Pt–N/Al PSC), and a slight increase in short-circuit current density. These results indicate that Pt–N is a new promising candidate as the cathode interlayer for highly efficient PSCs.
Co-reporter:Zhicheng Hu, Kai Zhang, Fei Huang and Yong Cao
Chemical Communications 2015 vol. 51(Issue 26) pp:5572-5585
Publication Date(Web):15 Jan 2015
DOI:10.1039/C4CC09433F
Water/alcohol soluble conjugated polymers (WSCPs), which can be processed from water/alcohol and other polar solvents, are suitable for the solution processing of multi-layer organic electronic devices. By using a thin layer WSCP as the cathode interfacial material, the resulting polymer light-emitting diodes (PLEDs) and polymer solar cells (PSCs) exhibited significant enhancements in their device performances. In this Feature Article, the authors aim to introduce a brief review of the recent developments and applications of WSCPs in highly efficient multi-layer solution processed PLEDs and PSCs.
Co-reporter:Peng Liu, Shuang Li, Yaocheng Jin, Linghui Qian, Nengyue Gao, Shao Q. Yao, Fei Huang, Qing-Hua Xu, and Yong Cao
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 12) pp:6754
Publication Date(Web):March 12, 2015
DOI:10.1021/acsami.5b00223
New red-emitting conjugated polymers have been successfully synthesized by incorporating classical two-photon absorption (TPA) units, electron-rich units, and a small amount of electron-deficient units along the polymer backbones. Water-dispersible nanoparticles (NPs) based on these polymers were also fabricated for applications in two-photon excitation fluorescence imaging of cell membrane. Through optimization of the polymer/matrix mass ratio and the initial feed concentration of the polymer solution, a high quantum yield (QY) of 24% was achieved for the red-emitting NPs in water. TPA cross section and two-photon action cross section values of these polymers at 750 nm reached up to 1000 GM and 190 GM per repeat unit in aqueous media, 2.5 × 105 GM and 4.7 × 104 GM per NP, respectively. Furthermore, these NPs displayed excellent photostability and biocompatibility. Their applications as two-photon excitation fluorescence probes for cell membrane imaging have been demonstrated in three different cell lines with excellent imaging contrast. These results demonstrated that these polymer NPs hold great potentials as excellent two-photon excitation fluorescence probes in various biological applications.Keywords: cell imaging; conjugated polymers; energy transfer; fluorescence; nanoparticles; two-photon
Co-reporter:Yanlin Lv, Peng Liu, Hui Ding, Yishi Wu, Yongli Yan, Heng Liu, Xuefei Wang, Fei Huang, Yongsheng Zhao, and Zhiyuan Tian
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 37) pp:20640
Publication Date(Web):September 4, 2015
DOI:10.1021/acsami.5b05150
Hybrid fluorescent nanoparticles (NPs) capable of fluorescing near-infrared (NIR) light (centered ∼730 nm) upon excitation of 800 nm laser light were constructed. A new type of conjugated polymer with two-photon excited fluorescence (TPEF) feature, P-F8-DPSB, was used as the NIR-light harvesting component and the energy donor while a NIR fluorescent dye, DPA-PR-PDI, was used as the energy acceptor and the NIR-light emitting component for the construction of the fluorescent NPs. The hybrid NPs possess δ value up to 2.3 × 106 GM per particle upon excitation of 800 nm pulse laser. The excellent two-photon absorption (TPA) property of the conjugated polymer component, together with its high fluorescence quantum yield (ϕ) up to 45% and the efficient energy transfer from the conjugated polymer to NIR-emitting fluorophore with efficiency up to 90%, imparted the hybrid NPs with TPEF-based NIR-input-NIR-output fluorescence imaging ability with penetration depth up to 1200 μm. The practicability of the hybrid NPs for fluorescence imaging in Hela cells was validated.Keywords: conjugated polymer; energy transfer; multiphoton fluorescence bioimaging; near-infrared (NIR) fluorescence; two-photon absorption
Co-reporter:Wei Li, Daojuan Wang, Suhao Wang, Wei Ma, Svante Hedström, David Ian James, Xiaofeng Xu, Petter Persson, Simone Fabiano, Magnus Berggren, Olle Inganäs, Fei Huang, and Ergang Wang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 49) pp:27106
Publication Date(Web):November 23, 2015
DOI:10.1021/acsami.5b09460
Two series of oligomers TQ and rhodanine end-capped TQ-DR were synthesized using a facile one-step method. Their optical, electrical, and thermal properties and photovoltaic performances were systematically investigated and compared. The TQ series of oligomers were found to be amorphous, whereas the TQ-DR series are semicrystalline. For the TQ oligomers, the results obtained in solar cells show that as the chain length of the oligomers increases, an increase in power conversion efficiency (PCE) is obtained. However, when introducing 3-ethylrhodanine into the TQ oligomers as end groups, the PCE of the TQ-DR series of oligomers decreases as the chain length increases. Moreover, the TQ-DR series of oligomers give much higher performances compared to the original amorphous TQ series of oligomers owing to the improved extinction coefficient (ε) and crystallinity afforded by the rhodanine. In particular, the highly crystalline oligomer TQ5-DR, which has the shortest conjugation length shows a high hole mobility of 0.034 cm2 V–1 s–1 and a high PCE of 3.14%, which is the highest efficiency out of all of the six oligomers. The structure–property correlations for all of the oligomers and the TQ1 polymer demonstrate that structural control of enhanced intermolecular interactions and crystallinity is a key for small molecules/oligomers to achieve high mobilities, which is an essential requirement for use in OPVs.Keywords: amorphous; crystallinity; hole mobility; oligomers; one-step method; organic photovoltaics
Co-reporter:Chunchen Liu, Sheng Dong, Ping Cai, Peng Liu, Shengjian Liu, Junwu Chen, Feng Liu, Lei Ying, Thomas P. Russell, Fei Huang, and Yong Cao
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 17) pp:9038
Publication Date(Web):April 13, 2015
DOI:10.1021/am5089956
A series of donor–acceptor type of π-conjugated copolymers based on tert-butoxycarbonyl (t-Boc) substituted indigo, isoindigo or diketopyrrolopyrrole as the acceptor unit and a benzodithiophene derivative as the donor unit was designed and synthesized. These copolymers can be readily dissolved in organic solvents and can produce uniform films by solution deposition. Thermal treatment of copolymer films at 200 °C for 10 min resulted in elimination of t-Boc side groups in nearly quantitative yield as suggested by thermogravimetric analysis and Fourier transform infrared spectroscopy. The elimination of the bulky t-Boc side groups resulted in the emergence of N–H···O═C hydrogen bonding interactions by virtue of the lactam structures of the indigo, isoindigo and diketopyrrolopyrrole units. Of particular interests is the distinctly increased field-effect mobility of these copolymers after thermal treatment, which may arise from the enhanced coplanarity and intermolecular ordering of the indigo, isoindigo or diketopyrrolopyrrole units after elimination of the bulky t-Boc side groups. These results demonstrate that the incorporation of latent side groups provides a viable strategy to construct conjugated polymers that can attain more ordered intermolecular stacking by simple thermal treatments. On the other hand, despite the thermal cleavage of t-Boc groups can also lead to increased ordering of polymer chains when blending with [6,6]-phenyl C71 butyric acid methyl ester, the photovoltaic performances of the resulting bulk heterojunction solar cells did not obviously increase due to the serious phase separation and coarsening of the film morphology.Keywords: conjugated polymers; hydrogen bonding; intermolecular ordering; organic field-effect transistor; polymer solar cell; thermal cleavage;
Co-reporter:Xuelong Huang, Guichuan Zhang, Cheng Zhou, Liqian Liu, Yaocheng Jin, Shengjian Liu, Lei Ying, Fei Huang and Yong Cao
Polymer Chemistry 2015 vol. 6(Issue 22) pp:4154-4161
Publication Date(Web):27 Apr 2015
DOI:10.1039/C5PY00201J
A series of narrow band gap conjugated copolymers comprising two electron-rich (donor, D) and one electron-deficient (acceptor, A) moieties regularly alternating along the polymer backbone were designed and synthesized. The ternary copolymers with the repeating unit in a D1–A–D2–A manner were constructed by copolymerizing a bisstannyled-D1 (D1 = cyclopentadithiophene or benzodithiophene-derivatives) and a dibromo-monomer (Br–A–D2–A–Br, D2 = dithienosilole, A = benzothiadiazole) through a palladium-catalyzed Stille polymerization. It was recognized that the optical properties, frontier molecular orbital energy levels and the photovoltaic performance of the resulting copolymers can be influenced by modifying the copolymerized D1 moiety. By carefully optimizing the electron-donating behaviours and substitutions of the D1 unit, bulk-heterojunction solar cells with a power conversion efficiency of 4.11% were achieved based on an inverted device configuration of ITO/PFN-OX/PBDT-O-ADA:PC71BM/MoO3/Al. These results demonstrated that the construction of regularly alternating narrow band gap conjugated ternary copolymers can be an effective strategy for the development of electron-donating materials for polymer solar cells.
Co-reporter:Liuyuan Lan, Zhiming Chen, Yunchuan Li, Lei Ying, Fei Huang and Yong Cao
Polymer Chemistry 2015 vol. 6(Issue 43) pp:7558-7569
Publication Date(Web):31 Aug 2015
DOI:10.1039/C5PY01235J
A series of donor–acceptor type of conjugated polymers were designed and synthesized via palladium catalyzed Stille copolymerization. These copolymers consisted of the electron-donating benzodithiophene or indacenodithiophene units and the electron-deficient cyclic imide substituted quinoxaline derivatives. It was noted that all copolymers exhibited typical dual-absorption characteristics in both solution and as thin films with an optical band gap in the range of 1.61–1.72 eV. In comparison with the copolymers based on the electron-deficient unit of 5,9-di(thien-2-yl)-2,3-diphenyl-7-octyl-6H-pyrrolo[3,4-g]quinoxaline-6,8(7H)-dione (TPQD) as the electron-accepting unit, the resultant copolymers based on the enlarged coplanar N-octyl-10,13-di(thien-2-yl)-2,7-dioctyldibenzo[a,c]phenazine-11,12-dicarboxylic imide (TBPDI) unit exhibited an obviously enhanced absorption coefficiency. All polymers showed relatively deep highest occupied molecular orbital energy levels ranging from −5.40 to −5.52 eV. It was also realized that the hole mobility of copolymers based on TBPDI is much higher than those based on the TPQD unit as measured by the space charge limited current method. Polymer solar cells with a device architecture of ITO/PEDOT:PSS/polymer:PC71BM/Ca/Al demonstrated that TBPDI-based copolymers exhibited higher performances than TPQD-based copolymers. The best device performance with a power conversion efficiency of 4.60% was achieved by using the indacenodithiophene-alt-TBPDI copolymer as the photoactive layer. Further optimization of devices by introducing a cathode interfacial layer and solvent vapor annealing in chloroform led to an impressive power conversion efficiency of 5.58%. These observations indicated that the developed TBPDI unit that has enlarged coplanarity can be a promising building block for the construction of highly efficient conjugated polymers for solar cell applications.
Co-reporter:Wanzhu Cai;Peng Liu;Yaocheng Jin;Qifan Xue;Feng Liu;Thomas P. Russell;Hin-Lap Yip;Yong Cao
Advanced Science 2015 Volume 2( Issue 8) pp:
Publication Date(Web):
DOI:10.1002/advs.201500095
Co-reporter:Chunhui Duan, Fei Huang and Yong Cao
Polymer Chemistry 2015 vol. 6(Issue 47) pp:8081-8098
Publication Date(Web):28 Sep 2015
DOI:10.1039/C5PY01340B
Solution processed bulk-heterojunction (BHJ) organic solar cells (OSCs) are an emerging next-generation photovoltaic technology. Laboratory-scale power conversion efficiencies (PCEs) of OSCs exceeding 10% in single-junction devices and approaching 12% in multijunction devices, respectively, have been achieved. However, the translation of this technology to industrial high throughput manufacturing needs the development of practically useful photoactive materials and processing methods that can produce efficient devices with a large active layer thickness. In this review, we introduce the factors that determine the optimal thickness of the active layer in OSCs at first. The significant advances in materials development and processing methods toward efficient thick film OSCs are summarized subsequently.
Co-reporter:Aihui Liang, Sheng Dong, Xiuhui Zhu, Fei Huang and Yong Cao
Polymer Chemistry 2015 vol. 6(Issue 34) pp:6202-6207
Publication Date(Web):14 Jul 2015
DOI:10.1039/C5PY00832H
Novel white light-emitting supramolecular phosphorescent polymers (SPPs) as a new class of solution-processable electroluminescent emitters have been first synthesized by efficient non-bonding assembly between bis(dibenzo-24-crown-8)-functionalized iridium complex monomers and bis(dibenzylammonium)-tethered co-monomers. These SPPs display good film morphology and high glass transition temperatures. The OLED device with a configuration of ITO/PEDOT:PSS/SPPs/CsF/Al exhibited a maximum luminous efficiency of 3.91 cd A−1 with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.46, 0.42), as the concentration of the monomer (FPyCr)2Irpic is 1 mol%. This approach is promising for realization of solution-processable all-phosphorescent materials for white organic light-emitting diodes.
Co-reporter:Wei Li, Qingduan Li, Chunhui Duan, Shengjian Liu, Lei Ying, Fei Huang, Yong Cao
Dyes and Pigments 2015 Volume 113() pp:1-7
Publication Date(Web):February 2015
DOI:10.1016/j.dyepig.2014.07.034
•A series of star-shaped π-conjugated molecules with triphenylamine as the core were prepared.•Symmetric and asymmetric star-shaped architectures bearing peripheral electron-withdrawing groups both were reported.•The electronic structures and absorption characteristics varied with the electron-withdrawing ability of the end groups.•The current work presents an effective molecular design strategy to broaden the absorption profiles.A series of star-shaped π-conjugated molecules with triphenylamine as the core and a thiophene unit as the π-bridge were designed and synthesized based on a donor-π-bridge-acceptor type of molecular framework. Various peripheral electron-deficient groups including octyl-2-cyanoacrylate, octyl-2,3-dicyanoacrylate and 1,3-diethyl-2-thiobarbituric were incorporated as electron-withdrawing moieties. By altering the terminal groups, star-shaped molecules with symmetric and asymmetric architectures were obtained. It was worth noting that the asymmetric molecules exhibited well-extended absorbance with the combination of absorption features of different donor-acceptor species. Electrochemical investigation indicated that the frontier molecular orbital energy levels can be modified by the terminal electron-withdrawing groups. Despite the fabricated organic photovoltaic devices based on the new molecules as electron-donating materials exhibited less pronounced performances, we surmise the current work illustrated an effective molecular design strategy for the realization of broad absorbance that was beneficial for the utilization of solar photon flux.
Co-reporter:Wenkai Zhong, Jin Xu, Sheng Sun, Junfei Liang, Bin Zhang, Ruifeng He, Linfeng Lan, Fei Huang, Lei Ying, Wei Yang, Junbiao Peng, Yong Cao
Organic Electronics 2015 Volume 23() pp:17-27
Publication Date(Web):August 2015
DOI:10.1016/j.orgel.2015.04.005
•Two novel donor-π-acceptor type of conjugated polymers were synthesized.•Selenophene copolymer showed higher absorptivity and intermolecular ordering.•Device performances improved obviously after replacing thiophene with selenophene.Two novel donor-π-acceptor type of conjugated polymers with thiophene or selenophene as the π-bridge between the electron-donating indolocarbazole and electron-accepting difluorobenzotriazole unit, were designed and synthesized through a palladium catalyzed Suzuki polymerization. The replacement of the thiophene bridge by selenophene shows negligible effects on the geometries of molecular chain, as indicated by theoretical calculation on the basis of density of functional theory. However, obvious bathochromic shift along with the increased intensity in the UV–vis absorption profile of selenophene based copolymers relative to their thiophene based counterparts are realized, as can be attributed to the more pronounced heavy atom effects of the selenium than the sulfur atom. Compared to the thiophene based copolymer, the selenophene based copolymer exhibited about one order of magnitude increase in hole mobility, from 0.0014 to 0.01 cm2 V−1 s−1, and about two times of magnitude increase in power conversion efficiency, from 1.01% to 2.39%, as evaluated by field effect transistors and bulk heterojunction polymer solar cells, respectively. These results indicated that the selection of appropriate π-bridge by is crucial for the improvement of performance of π-conjugated polymers.
Co-reporter:Xuelong Huang, Guichuan Zhang, Cheng Zhou, Shengjian Liu, Jie Zhang, Lei Ying, Fei Huang and Yong Cao
New Journal of Chemistry 2015 vol. 39(Issue 5) pp:3658-3664
Publication Date(Web):16 Feb 2015
DOI:10.1039/C4NJ02350A
A series of donor–acceptor type of π-conjugated oligomers based on dithieno[3,2-b;2′,3′-d]silole as the electron donor and 2,1,3-benzothiadiazole as the electron acceptor were designed and synthesized. It was found that the elongation of the molecular lengths of the chromophores can significantly influence the thermal properties, UV-vis absorption, electrochemical properties, and photovoltaic performances of fabricated organic solar cells. The higher molecular weight chromophore exhibited a narrower band gap compared to lower molecular weight counterparts. Solution processed bulk-heterojunction organic solar cells were fabricated with the inverted device structure of ITO/PFN-OX/oligomer:PCBM/MoO3/Al, in which the best device performance was achieved with a power conversion efficiency of 1.12%. These results indicated that the elongation of the molecular length of π-conjugated small-molecules can be an effective strategy for improving the organic photovoltaic performance of narrow band-gap chromophores.
Co-reporter:Zhicheng Hu, Sheng Dong, Qifan Xue, Rongguo Xu, Hin-Lap Yip, Fei Huang, Yong Cao
Organic Electronics 2015 Volume 27() pp:46-52
Publication Date(Web):December 2015
DOI:10.1016/j.orgel.2015.08.023
•Au NPs were synthesized using a tailored-made amine-containing polymer (PN4N) as template to form the Au NPs-PN4N composites.•Au NPs-PN4N composite can be used as an efficient cathode interfacial material for polymer and perovskite solar cells.•Au NPs doping in both PEDOT:PSS and PN4N exhibit an synergistic effect to improve solar cell performance.•PCEs of 6.82% and 13.7% were achieved for PCDTBT/PC71BM based polymer solar cells and planar heterojunction perovskite solar cells, respectively.A new approach for the synthesis of gold nanoparticles (Au NPs) via a simple and fast in-situ generation method using an amine-containing polymer (PN4N) as both stabilizer and reducing agent is reported. The application of the Au NPs-PN4N hybrid material as efficient interfacial layer in different types of solar cells was also explored. The synthesized Au NPs show good uniformity in size and shape and the Au NPs doped PN4N hybrid composites exhibit high stability. Amine-containing polymers are good cathode interfacial materials (CIMs) in polymer solar cells (PSCs) and planar heterojunction perovskite solar cells (PVKSCs). The performance of the PSCs with Au NPs doped PN4N CIMs is largely improved when compares to devices with pristine PN4N CIM due to the enhanced electronic properties of the doped PN4N. Furthermore, by incorporating larger Au NPs into PEDOT:PSS to enhance absorption of the light harvesting layer, power conversion efficiencies (PCEs) of 6.82% and 13.7% are achieved for PSC with PCDTBT/PC71BM as the light harvesting materials and PVKSC with a ∼280 nm-thick CH3NH3PbI3−xClx perovskite layer, respectively. These results indicate that Au NPs doped into both PEDOT:PSS and PN4N interlayers exhibited a synergistic effect in performance improvement of PSCs and PVKSCs.
Co-reporter:Pengzhi Guo, Yangjun Xia, Fei Huang, Guoping Luo, Jianfeng Li, Peng Zhang, Yuancheng Zhu, Chunyan Yang, Hongbin Wu and Yong Cao
RSC Advances 2015 vol. 5(Issue 17) pp:12879-12885
Publication Date(Web):15 Jan 2015
DOI:10.1039/C4RA14532A
A low band gap conjugated polymer derived from alkylthieno-2-yl flanked dithieno[2,3-d:2′,3′-d′]benzo[1,2-b:4,5-b′]dithiophene and a naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole derivative was first synthesized, and high performance inverted photovoltaic solar cells with a power conversion efficiency of 7.52% have been demonstrated.
Co-reporter:Qifan Xue, Zhicheng Hu, Chen Sun, Ziming Chen, Fei Huang, Hin-Lap Yip and Yong Cao
RSC Advances 2015 vol. 5(Issue 1) pp:775-783
Publication Date(Web):25 Nov 2014
DOI:10.1039/C4RA11739E
A polymer with tailored chemical functionality was introduced as a processing additive to control the film formation of the CH3NH3PbI3 perovskite structure, leading to enhanced photovoltaic performance in a PEDOT:PSS/perovskite/PCBM-based planar heterojunction solar cell under optimized conditions. By adjusting the polymer doping content and the processing solvent, the grain size, film coverage and the optical properties of the perovskite films can be effectively tuned. At optimized conditions, the planar heterojunction solar cell composed of a thin layer of perovskite–polymer film (∼50 nm) exhibits an average PCE of 6.16% with a Voc of 1.04 V, a Jsc of 8.85 mA cm−2 and a FF of 0.65, which are much higher than those of the control device with a pristine perovskite film. The higher performance was attributed to improved morphology and interfaces of the perovskite–polymer films, which reduced the undesired contact between PEDOT:PSS and PCBM and minimized the shunting paths in the device. In addition, since the fabrication process for the perovskite solar cells can be performed at low temperature, flexible cells built on plastic substrates can therefore be realized with a PCE of 4.35%.
Co-reporter:Liqian Liu;Guichuan Zhang;Baitian He
Chinese Journal of Chemistry 2015 Volume 33( Issue 8) pp:902-908
Publication Date(Web):
DOI:10.1002/cjoc.201500265
Abstract
Two novel naphtho[1,2-c:5,6-c]bis(1,2,5-thiadiazole) and alkoxylphenyl substituted benzodithiophene based copolymers were developed as the donor materials for polymer solar cells. The resulting copolymers exhibit broad absorption bands in the range of 500–800 nm in thin films and deep highest occupied molecular orbital energy levels of −5.39 eV and −5.36 eV, respectively. The best device performance was achieved by P1, with an open-circuit voltage of 0.85 V, a short-circuit current density of 8.65 mA·cm−2, a fill factor of 37.8%, and a power conversion efficiency of 2.78%.
Co-reporter:Wei Li;Qingduan Li;Shengjian Liu;Chunhui Duan;Lei Ying
Science China Chemistry 2015 Volume 58( Issue 2) pp:257-266
Publication Date(Web):2015 February
DOI:10.1007/s11426-014-5275-8
Four new 2D donor-acceptor conjugated polymers were designed and synthesized. These new polymers comprised fluorene-alt-triphenylamine or carbazole-alt-triphenylamine as the backbones, and pendants with 2,1,3-benzothiadiazole (BT) or naphtho[ 1,2-c:5,6-c]bis[1,2,5]thiadiazole (NT) in a triphenylamine unit as the side groups. By changing the acceptor BT for a stronger electron-withdrawing unit of NT moiety in the side chain, the energy levels, absorption spectra, band gaps, and charge-transport abilities of the resultant polymers could be effectively tuned. Bulk heterojunction solar cells with these polymers as the electron donors and (6,6)-phenyl-C71-butyric acid methyl ester as the electron acceptor exhibited high open-circuit voltage (more than 0.8 eV). The power conversion efficiency can be improved from 1.37% to 3.52% by replacing the BT with an NT moiety, which indicates that introducing NT as the side-chain building block can be an effective strategy to construct efficient 2D conjugated polymers for PSCs.
Co-reporter:Liuyuan Lan, Guichuan Zhang, Yang Dong, Lei Ying, Fei Huang, Yong Cao
Polymer 2015 Volume 67() pp:40-46
Publication Date(Web):12 June 2015
DOI:10.1016/j.polymer.2015.04.061
•Two new medium band gap conjugated copolymers containing naphtha[1,2-c:5,6-c]bis(2-octyl-[1,2,3]triazole) were synthesized.•The resulted copolymers showed medium band gap of about 1.8 eV.•Bulk-heterojunction polymer solar cells based on copolymer P1 exhibited a moderate power conversion efficiency of 2.58%.Two new donor–acceptor type of conjugated polymers derived from naphtho[1,2-c:5,6-c]bis(2-octyl-[1,2,3]triazole) and dithieno[3,2-b:2′,3′-d]silole were prepared by Stille polymerization. The thermal, electrochemical and photophysical properties of these copolymers were studied. Both polymers have excellent thermal stability with decomposition temperature up to 430 °C. The copolymers show medium band gap of ∼1.8 eV. Inverted bulk heterojunction solar cells in which these copolymers are used as electron donors in combination with PC61BM as the electron acceptor were fabricated. Under AM 1.5 G illumination at 100 mW/cm2, device based on P1:PC61BM as the photoactive layer displays a moderate power conversion efficiency of 2.58% with an open-circuit voltage of 0.83 V, a short circuit current of 5.53 mA/cm2, and a fill factor of 56.13%. Our work indicates that naphtho[1,2-c:5,6-c]bis(2-octyl-[1,2,3]triazole) can be a promising electron-deficient building block for designing donor–acceptor type of polymeric materials.
Co-reporter:Xia Guo;Maojie Zhang;Wei Ma;Long Ye;Shaoqing Zhang;Shengjian Liu;Harald Ade;Jianhui Hou
Advanced Materials 2014 Volume 26( Issue 24) pp:4043-4049
Publication Date(Web):
DOI:10.1002/adma.201400411
Co-reporter:Cheng Mu;Peng Liu;Wei Ma;Kui Jiang;Jingbo Zhao;Kai Zhang;Zhihua Chen;Zhanhua Wei;Ya Yi;Jiannong Wang;Shihe Yang;Antonio Facchetti;Harald Ade;He Yan
Advanced Materials 2014 Volume 26( Issue 42) pp:7224-7230
Publication Date(Web):
DOI:10.1002/adma.201402473
Co-reporter:Yanming Sun;Jason Seifter;Ming Wang;Louis A. Perez;Chan Luo;Guillermo C. Bazan;Yong Cao;Alan J. Heeger
Advanced Energy Materials 2014 Volume 4( Issue 6) pp:
Publication Date(Web):
DOI:10.1002/aenm.201301601
Co-reporter:Cheng Gu;Youchun Chen;Zhongbo Zhang;Shanfeng Xue;Shuheng Sun;Chengmei Zhong;Huanhuan Zhang;Ying Lv;Fenghong Li;Yuguang Ma
Advanced Energy Materials 2014 Volume 4( Issue 8) pp:
Publication Date(Web):
DOI:10.1002/aenm.201301771
Co-reporter:Xiaowen Hu;Chao Yi;Ming Wang;Chih-Hao Hsu;Shengjian Liu;Kai Zhang;Chengmei Zhong;Xiong Gong;Yong Cao
Advanced Energy Materials 2014 Volume 4( Issue 15) pp:
Publication Date(Web):
DOI:10.1002/aenm.201400378
Co-reporter:Cheng Zhou;Yamin Liang;Feng Liu;Chen Sun;Xuelong Huang;Zengqi Xie;Jean Roncali;Thomas P. Russell;Yong Cao
Advanced Functional Materials 2014 Volume 24( Issue 47) pp:7538-7547
Publication Date(Web):
DOI:10.1002/adfm.201401945
Well-defined conjugated oligomers (Sn) containing from 1 to 8 units of a tricyclic building block involving a dioctyloxybenzothiadiazole unit with two thienyl side rings (S1) are synthesized by a bottom-up approach. UV–Vis absorption data of solutions show that chain extension produces a narrowing of the HOMO–LUMO gap (ΔE) to values slightly smaller than that of the parent polymer (P1). Plots of ΔE and of the band gap of films (E g) versus the reciprocal chain length show that ΔE and E g converge towards a limit corresponding to an effective conjugation length (ECL) of 7–8 S1 units. UV–Vis absorption and photoluminescence data of solutions and solid films show that chain extension enhances the propensity to inter-chain aggregation. This conclusion is confirmed by GIXD analyses which reveal that the edge-on orientation of short-chain systems evolves toward a face-on orientation as chain length increases while the π-stacking distance decreases beyond 7 units. The results obtained on solution-processed BHJ solar cells show a progressive improvement of power conversion efficiency (PCE) with chain extension; however, the convergence limit of PCE remains inferior to that obtained with the polymer. These results are discussed with regard to the role of mono/polydispersity and chain aggregation.
Co-reporter:Peng Liu, Kai Zhang, Feng Liu, Yaocheng Jin, Shengjian Liu, Thomas P. Russell, Hin-Lap Yip, Fei Huang, and Yong Cao
Chemistry of Materials 2014 Volume 26(Issue 9) pp:3009
Publication Date(Web):April 14, 2014
DOI:10.1021/cm500953e
A new family of polythienothiophene-co-benzodithiophene copolymers with different amounts of fluorine decoration (PBFx) had been successfully synthesized. Detailed structure–property investigations covering physical properties, morphology, and solar cell performance with respect to the fluorine content in the polymers were performed by a series of structural characterization techniques. A PCE of 8.75% was obtained with the highest fluorinated polymer; the morphological trends, as well as the crystalline structure, were also investigated, shedding light on this important material modification.
Co-reporter:Kai Zhang, Chengmei Zhong, Shengjian Liu, Ai-hui Liang, Sheng Dong and Fei Huang
Journal of Materials Chemistry A 2014 vol. 2(Issue 17) pp:3270-3277
Publication Date(Web):11 Nov 2013
DOI:10.1039/C3TC32022G
Highly efficient inverted white organic light emitting diodes (IWOLEDs) were achieved by a simple solution processing technique, in which cross-linkable amino-functionalized polyfluorene poly[9,9-bis(6′-(N,N-diethylamino)hexyl)-fluorene-alt-9,9-bis(3-ethyl(oxetane-3-ethyoxy)-hexyl)-fluorene] (PFN-OX) served as electron injection/transporting layer (EIL) deposited onto indium tin oxide (ITO) directly without n-type inorganic metal oxides (MOs). The light emitting layer consisted of a (poly(N-vinylcarbazole) (PVK)/1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl]phenylene (OXD-7) blend as host and phosphorescent iridium complexes as guests. Our results demonstrated that ITO could serve as cathode and inject electrons into the phosphorescent system directly and efficiently by using PFN-OX as single EIL. As a result, a high performance IWOLED device with Commission Internationale de L'Eclairage (CIE) coordinate of (0.35, 0.45), colour rendering index (CRI) of 70, maximum luminous efficiency (LE) of 18.1 cd A−1 and maximum power efficiency (PE) of 6.6 lm W−1 was achieved. This result provides an easy way of fabricating multilayer solution processed high efficiency IWOLEDs.
Co-reporter:Xinliang Ye, Jie Zhang, Hui Chen, Xiaohui Wang, and Fei Huang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 7) pp:5113
Publication Date(Web):March 13, 2014
DOI:10.1021/am500270a
Novel self-assembled water-soluble nanomicelles that contain fluorescent conjugated polymers (poly(9,9-dioctylfluorene) (PFO) or poly[2,7-(9,9-dihexylfluorene)-alt-4,4′-phenylether] (PF-PE)) have been obtained and used as the highly sensitive/selective platform for Sudan dye detection. The Fluorescent nanomicelles exhibited a highly selective fluorescence quenching by the prohibited food additive Sudan I, while not for the natural pigments: Capsanthin and Beta-carotene, due to the more suitable matching of the LUMOs (lowest unoccupied molecular orbital) of the conjugated polymers with that of Sudan I molecules. The Stern–Volmer constants (KSV) of PF-PE/F127 and PFO/F127 for Sudan I were 1 040 480 and 665 000 M–1, respectively, which were more than 100 times higher than those of the same conjugated polymers in the orgainc solvents. The significantly enhanced sensitivity was due to the collective effect of the F127 micelles to both chromophore and analyte, through which the fluorophone–analyte binding interaction is significantly strengthened and efficient photoinduced charge transfer occurs. The as-proposed materials and approach may be potentially applied in the real-time food safety screening.Keywords: amphiphilic polymer carriers; biological sensing; conjugated polymers nanomicelles; hydrophobic synthetic dyes; self-assembly;
Co-reporter:Jie Zhang, Sheng Dong, Kai Zhang, Aihui Liang, Xiye Yang, Fei Huang and Yong Cao
Chemical Communications 2014 vol. 50(Issue 60) pp:8227-8230
Publication Date(Web):05 Jun 2014
DOI:10.1039/C4CC03080J
A series of blue supramolecular polymers with different counterions based on host–guest interactions were developed for polymer light-emitting diodes. It was found that the counterions play important roles in the resulting materials' supramolecular interactions as well as the device performance.
Co-reporter:Shengjian Liu, Chengmei Zhong, Sheng Dong, Jie Zhang, Xuelong Huang, Cheng Zhou, Junming Lu, Lei Ying, Lei Wang, Fei Huang, Yong Cao
Organic Electronics 2014 Volume 15(Issue 4) pp:850-857
Publication Date(Web):April 2014
DOI:10.1016/j.orgel.2014.01.016
•A family of aminoalkyl-functionalized blue-, green- and red-emitting polyfluorene derivatives were synthesized.•The aminoalkyl-functionalized copolymers exhibited dual functions of efficient light emission and electron injection.•Device performances can be optimized by varying the molar ratios of the incorporated aminoalkyl side groups.A family of aminoalkyl functionalized blue-, green- and red-emitting polyfluorene based copolymers were synthesized by Suzuki copolymerization. Dibenzothiophene-S,S-dioxide-3,7-diyl (FSO), 2,1,3-benzothiadiazole (BT) and 4,7-di-2-thienyl-2,1,3-benzothiadiazole (DTBT) were incorporated into the backbone of copolymers as blue, green and red chromophores, respectively. It was realized that for all these aminoalkyl functionalized copolymers, the thermal stabilities, UV–vis absorption and electrochemical properties are not affected by molar ratio of aminoalkyl side groups. However, the increased amino-groups content can induce the formation of excimer in FSO based blue-emitting copolymer, which in turn leaded to broadened photoluminescence and electroluminescence spectra along with decreased emission efficiency. In contrast, device based on green and red-emitting copolymers exhibited stable emission, and device performance improved progressively with the enhanced content of aminoalkyl co-monomers. Comparing to the copolymers without aminoalkyl side chains, aminoalkyl functioned materials exhibited distinctly improved device performances for the application as emissive layer in light emitting diodes using high work-function Al as cathode due to the formation of interfacial dipoles that can facilitate electron injection. The maximum luminous efficiency of 3.28, 7.31 and 0.79 cd A−1 was achieved based on copolymers BFN1, GFN15 and RFN15, respectively with device architecture of ITO/PEDOT:PSS/PVK/copolymer/Al. These results indicate that aminoalkyl functionalized copolymers can have great potential for the application as efficient light-emitting layer with high work-function/air-stable cathode.Graphical abstract
Co-reporter:Chunchen Liu, Wenzhan Xu, Xing Guan, Hin-Lap Yip, Xiong Gong, Fei Huang, and Yong Cao
Macromolecules 2014 Volume 47(Issue 24) pp:8585-8593
Publication Date(Web):December 2, 2014
DOI:10.1021/ma501989s
A highly soluble anthracene cyclic adduct with a thermally cleavable substituent was synthesized, and it was used as a donor unit in a series of donor–acceptor type conjugated copolymers with improved processability. The removable group was eliminated under elevated temperature through retro Diels–Alder reaction, which offered the corresponding copolymers with better planarity and rigidity. Thermogravimetric analysis (TGA), FT-IR, and UV–vis spectroscopy were carried out to study the thermal cleavage process. Uniform films were easily formed from these precursor copolymers due to their good solution processabilty. Polymer solar cells were successfully fabricated through applying thermal annealing treatment on the blend films that were spin-coated from solutions of the precursor copolymers blended with fullerene derivatives. The best polymer solar cell device with a power conversion efficiency (PCE) of 2.15% was achieved based on copolymer PCOAEHDPP.
Co-reporter:Aihui Liang;Lei Ying
Journal of Inorganic and Organometallic Polymers and Materials 2014 Volume 24( Issue 6) pp:905-926
Publication Date(Web):2014 November
DOI:10.1007/s10904-014-0099-8
Recent progresses of iridium complexes-containing macromolecules, including the linear polymers, dendrimers as well as supramolecular polymers, for solution-processable phosphorescent organic light-emitting devices, have been reviewed. The synthesis, structural characterization and optoelectronic properties of iridium-based electrophosphorescent materials are summarized.
Co-reporter:Li-Qian Liu;Gui-Chuan Zhang;Peng Liu;Dr. Jie Zhang;Sheng Dong;Dr. Ming Wang;Yu-Guang Ma; Hin-Lap Yip; Fei Huang
Chemistry – An Asian Journal 2014 Volume 9( Issue 8) pp:2104-2112
Publication Date(Web):
DOI:10.1002/asia.201402019
Abstract
Four donor–acceptor-type low-bandgap conjugated polymers based on a naphtho[1,2-c:5,6-c]bis(1,2,5-thiadiazole) (NT) acceptor and different donors bridged by a bithiophene spacer have been synthesized through Suzuki or Stille polymerization reactions. Fluorene (F), carbazole (Cz), alkylidene fluorene (AF), and benzodithiophene (BDT) were selected as the donor units to produce a series of new conjugated polymers. Owing to the different electron-donating ability of the donor units, the energy levels, absorption spectra, bandgaps, and carrier mobilities of the resulting polymers were systematically tuned. Bulk-heterojunction-type polymer solar cells based on the new polymers and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) were investigated and all of the devices exhibited good photovoltaic performance, with power-conversion efficiencies (PCEs) over 3 %. The best device performance was achieved by PF-C12NT, with an open-circuit voltage (Voc) of 0.87 V, a short-circuit current density (Jsc) of 12.19 mA cm−2, a fill factor (FF) of 61.36 %, and a PCE of 6.51 % under simulated sunlight (100 mW cm−2, AM 1.5G).
Co-reporter:Chunhui Duan, Kai Zhang, Chengmei Zhong, Fei Huang and Yong Cao
Chemical Society Reviews 2013 vol. 42(Issue 23) pp:9071-9104
Publication Date(Web):30 Aug 2013
DOI:10.1039/C3CS60200A
Water/alcohol-soluble conjugated polymers (WSCPs) and small molecules (WSCSs) are materials that can be processed from water or other polar solvents. They provide good opportunities to fabricate multilayer organic optoelectronic devices without interface mixing by solution processing, and exhibit a promising interface modification ability for metal or metal oxide electrodes to greatly enhance the device performance of solar cells. Moreover, owing to their intriguing processability, WSCPs and WSCSs have great potential for applying environmentally friendly processing technologies to fabricate solar cells. In this review, the authors give an overview of recent developments in WSCPs and WSCSs, including their molecular design, material synthesis, functional principles and application as interface modification layers and photoactive components in emerging photovoltaic technologies such as organic/polymer solar cells, organic–inorganic hybrid solar cells and dye-sensitised solar cells.
Co-reporter:Chunhui Duan, Wanzhu Cai, Ben B. Y. Hsu, Chengmei Zhong, Kai Zhang, Chunchen Liu, Zhicheng Hu, Fei Huang, Guillermo C. Bazan, Alan J. Heeger and Yong Cao
Energy & Environmental Science 2013 vol. 6(Issue 10) pp:3022-3034
Publication Date(Web):24 Jul 2013
DOI:10.1039/C3EE41838C
To develop environmentally friendly solvent processed high performance polymer solar cells (PSCs), an alcohol soluble narrow-band-gap conjugated polymer PCDTBT-N and an alcohol soluble C70 fullerene derivative PC71BM-N, which were functionalized with pendant tertiary amino groups, were developed and used as active layers in PSCs and as buffer layers in metal–semiconductor interfaces. Though solar cells with active layers containing amino groups showed no photovoltaic properties regardless of the processing conditions, both PCDTBT-N and PC71BM-N performed well as buffer layers to improve electron collection in PSCs. Space charge limited current (SCLC), field effect transistor (FET) and cyclic voltammetry (CV) studies revealed that the amino groups act as hole traps and disable hole transport in active layers. Moreover, ultraviolet photoelectron spectroscopy (UPS) indicates electronic structure changes and Fermi level shifts upon complexation of amino groups and the fullerene core, which may diminish the electron-accepting capacity of fullerenes, and may potentially provide a different kind of hole trap in the devices. The underlying mechanisms of the puzzling behavior of PCDTBT-N and PC71BM-N in different layers of PSCs were studied by numerical simulation, which indicates that hole traps distributed in the BHJ layer reduce device performance, conversely hole traps concentrated near the metal electrode can improve device performance. Besides, the formation of an amino group:C70 complex is another important cause of the performance improvements of the resulting solar cells using PCDTBT-N and PC71BM-N as buffer layers, due to the reduced transport loss for efficient electron collection through the n-doping of PC71BM at the interface of the buffer layer and the active layer.
Co-reporter:Yang Dong;Xiaowen Hu;Chunhui Duan;Peng Liu;Shengjian Liu;Liuyuan Lan;Dongcheng Chen;Lei Ying;Shijian Su;Xiong Gong;Yong Cao
Advanced Materials 2013 Volume 25( Issue 27) pp:3683-3688
Publication Date(Web):
DOI:10.1002/adma.201301547
Co-reporter:Shengjian Liu ; Kai Zhang ; Junming Lu ; Jie Zhang ; Hin-Lap Yip ; Fei Huang ;Yong Cao
Journal of the American Chemical Society 2013 Volume 135(Issue 41) pp:15326-15329
Publication Date(Web):October 2, 2013
DOI:10.1021/ja408363c
An amino-functionalized conjugated metallopolymer PFEN-Hg was developed as a cathode interlayer for inverted polymer solar cells. The resulting devices exhibited significantly improved performance with power conversion efficiencies exceeding 9%. Moreover, good device performance was achievable with the PFEN-Hg over a wider range of film thickness, likely due to the Hg–Hg interactions and improved π–π stacking.
Co-reporter:Ai-Hui Liang, Kai Zhang, Jie Zhang, Fei Huang, Xu-Hui Zhu, and Yong Cao
Chemistry of Materials 2013 Volume 25(Issue 6) pp:1013
Publication Date(Web):March 4, 2013
DOI:10.1021/cm400333c
The synthesis of supramolecualr phosphorescent polymers (SPPs) as a novel class of solution-processable electroluminescent (EL) emitters was presented. The SPPs were formed by utilizing the efficient nonbonding self-assembly of luminescent iridium monomer 1 and “terfluorenyl”-based monomers 2 and 3, tethered with either a crown ether or dibenzylammonium unit. The supramolecular assembly process was monitored and illustrated by 1H nuclear magnetic resonance (NMR) and viscosity measurement. Moreover, the SPPs exhibit an intrinsic glass transition with a glass-transition temperature (Tg) of 72.5–81.5 °C, which is absent in the monomers. The characterization of organic light-emitting diodes that consisted of these SPPs as an emitter gave an efficiency of 14.6 cd A–1 at a luminance of 450 cd m–2. Considering the good solution processability and catalyst-free polymerization process for the designed SPPs, combining the good device performances, the present study provide a promising alternative route to develop solution processed phosphorescent light-emitting materials for optoelectronic applications.Keywords: iridium complex; organic light-emitting diodes; phosphorescence; solution process; supramolecular polymer;
Co-reporter:Chunhui Duan, Kai Zhang, Xing Guan, Chengmei Zhong, Hongmei Xie, Fei Huang, Junwu Chen, Junbiao Peng and Yong Cao
Chemical Science 2013 vol. 4(Issue 3) pp:1298-1307
Publication Date(Web):08 Jan 2013
DOI:10.1039/C3SC22258F
A series of new water/alcohol-soluble conjugated polymers (WSCPs) poly[(9,9-bis((N-(4-sulfonate-1-butyl)-N,N-dimethylammonium)propyl)-2,7-fluorene)-alt-N-phenyl-4,4′-diphenylamine)] (PFNSO-TPA), poly[(9,9-bis((N-(4-sulfonate-1-butyl)-N,N-dimethylammonium)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFNSO) and poly[(9,9-bis((N-(4-sulfonate-1-butyl)-N,N-dimethylammonium)propyl)-2,7-fluorene)-alt-4,7-(2,1,3-benzothiadiazole)] (PFNSO-BT), comprising identical sulfobetaine zwitterionic groups on their side chains but different conjugated main chain structures, were designed and developed as interface modification materials to improve electron collection in bulk-heterojunction polymer solar cells (PSCs), and to improve electron injection/transporting in polymer light-emitting diodes (PLEDs). The resulting WSCPs possess integrated advantages of excellent alcohol processability, interface modification functions and mobile ion free nature. The relationships between the WSCPs main chain structures and properties (including optical/electrical properties and interface modification functions in resulting devices) were investigated systematically. In PSCs, it was found that the WSCPs interface modification properties led to varying differences, but all of them can boost the photovoltaic performances of PSCs; encouragingly, a high power conversion efficiency (PCE) of 8.74% could be achieved. In PLEDs, the interface modification functions of the WSCPs strongly depend upon their conjugated main chain structures. The WSCPs should possess suitable energy levels to match well with the light-emitting layer (EML), even though the electron injection from metal cathode was efficient. Our results show promising potentials of WSCPs as interface modification layers in organic/polymer optoelectronic devices, and provide new insights for the development of new interface modification materials in the future.
Co-reporter:Chunchen Liu, Wanzhu Cai, Xing Guan, Chunhui Duan, Qifan Xue, Lei Ying, Fei Huang and Yong Cao
Polymer Chemistry 2013 vol. 4(Issue 14) pp:3949-3958
Publication Date(Web):23 Apr 2013
DOI:10.1039/C3PY00430A
A series of narrow band gap donor–acceptor type conjugated copolymers based on 2,6-linked anthracene derivatives are synthesized via Suzuki copolymerization. The resulting copolymers typically exhibit dual absorption characteristics in both solution and as thin films with optical band gaps in the range of 1.85–2.13 eV. By varying the substitutions from alkyloxy to aromatic thienyl and phenyl groups in the 9,10-positions of the anthracene unit, the constructed two-dimensional 2,6-linked anthracene structures lead to broader absorption, lower-lying highest occupied molecular orbitals, as well as improved charge carrier mobilities of the resulting copolymers relative to the alkyloxy side chain substituted counterparts. Additionally, it was found that the sizes of the substitutions in the benzo[c][1,2,5]thiadiazole acceptor also play an important role in the optoelectronic properties of these anthracene based conjugated copolymers. The best polymer solar cell device with a power conversion efficiency of 4.34% and a high open circuit voltage of 0.98 V was realized based on the resulting materials. Our results indicate that substantial optimization in the sizes and patterns of substitutions of both the 2,6-linked anthracene donor and benzo[c][1,2,5]thiadiazole acceptor may potentially lead to high performance narrow band gap copolymers for solar cell applications.
Co-reporter:Ai-hui Liang;Sheng Dong;Kai Zhang;Xiao Xiao;Xu-Hui Zhu;Yong Cao
Macromolecular Rapid Communications 2013 Volume 34( Issue 16) pp:1301-1305
Publication Date(Web):
DOI:10.1002/marc.201300254
Co-reporter:Yang Dong, Wanzhu Cai, Ming Wang, Qingduan Li, Lei Ying, Fei Huang, Yong Cao
Organic Electronics 2013 Volume 14(Issue 10) pp:2459-2467
Publication Date(Web):October 2013
DOI:10.1016/j.orgel.2013.06.002
•Three novel narrow band gap conjugated copolymers containing [1,2,5]thiadiazolo[3,4-f]benzotriazole were synthesized.•The copolymers exhibited comparatively narrow band gap of ca. 1 eV.•Broad photocurrent response up to 1.1 μm was realized.Three novel donor–acceptor type of narrow band gap conjugated copolymers were synthesized through a palladium-catalyzed Stille copolymerization based on [1,2,5]thiadiazolo[3,4-f]benzotriazole (TBZ) derivatives as acceptor and 4,8-di(2,3-didecylthiophen-5-yl)-benzo[1,2-b:4,5-b′]dithiophene (BDT) as donor. All resulted copolymers exhibited absorbance up to near-infrared region along with relatively narrow band gap in the range of 0.96–1.10 eV. Cyclic voltammetry measurements illustrated that the highest occupied molecular orbital energy levels of copolymers lay in the range of −5.04 to −5.13 eV, and lowest unoccupied molecular orbital (LUMO) energy levels were in the range of −4.03 to −4.16 eV. Photovoltaic performances were evaluated based on the resulted copolymers as donor and [6,6]-phenyl-C60 butyric acid methyl ester (PC61BM) as acceptor with optimized weight ratio of 1:2. All devices displayed comparatively low power conversion efficiencies in the range of 0.1–0.4% due to the low-lying LUMO energy levels. Broad photocurrent response up to near infrared region of 1.1 μm was realized for copolymer P2 that containing thiophene unit as the bridge between BDT and TBZ moieties, indicating that it can be potentially applied for near infrared photodetectors.Graphical abstract
Co-reporter:Jie Zhang, Kai Zhang, Shengjian Liu, Aihui Liang, Xuelong Huang, Fei Huang, Junbiao Peng and Yong Cao
RSC Advances 2013 vol. 3(Issue 12) pp:3829-3835
Publication Date(Web):23 Jan 2013
DOI:10.1039/C3RA40249E
A large band gap supramolecular polymer based on host–guest interactions was developed as the host material for phosphorescent organic light-emitting diodes. The dibenzo-24-crown-8, and dibenzylammonium salt functionalized fluorene-based large band gap compounds 1 and 2 were developed as the host and guest monomers, respectively. The resulting linear supramolecular polymer (SP) 3 was obtained from the self-organization of the host and guest monomers, which was validated by nuclear magnetic resonance, viscosity and differential scanning calorimetry studies. The SP 3 maintained the triplet energy level of the host monomer 1 and the guest monomer 2. The resulting device based on the supramolecular host material and a yellow-phosphorescent complex Ir(Flpy)3 achieved a maximum luminance efficiency of 18.2 cd A−1.
Co-reporter:Xiaowen Hu, Yang Dong, Fei Huang, Xiong Gong, and Yong Cao
The Journal of Physical Chemistry C 2013 Volume 117(Issue 13) pp:6537-6543
Publication Date(Web):March 14, 2013
DOI:10.1021/jp4001237
High-detectivity near-infrared (NIR) polymer photodetectors (PDs) fabricated by a novel low-bandgap semiconducting polymer blended with fullerene derivatives are reported. Operating at room temperature, the polymer PDs have a spectral response from 400 to 1100 nm. By incorporation of an alcohol/water-soluble polymer as a cathode interlayer in bulk heterojunction polymer PDs, the polymer PDs exhibit a high detectivity of 1.75 × 1013 cm•Hz1/2/W at 800 nm. These results demonstrated that the NIR polymer PDs are comparable to Si-based PDs.
Co-reporter:ShengJian Liu;ZhiPeng Zhang;DongCheng Chen;ChunHui Duan
Science China Chemistry 2013 Volume 56( Issue 8) pp:1119-1128
Publication Date(Web):2013/08/01
DOI:10.1007/s11426-013-4864-2
A series of alcohol soluble amino-functionalized carbazole-based copolymers were synthesized via Suzuki coupling reaction. The pendent amino groups endow them high solubility in polar solvents, as well as efficient electron injection capability from high work-function metals. The relationships between the photophysical and electrochemical properties and the polymer backbone structure were systematically investigated. These alcohol-soluble carbazole-based copolymers were used as cathode interlayers between the high work-function metal Al cathode and P-PPV emissive layer in polymer light-emitting diodes with device structure of ITO/PEDOT:PSS/P-PPV/interlayer/Al. The resulting devices exhibited improved performance due to the better electron injection/transporting ability of the designed copolymers from Al cathode to the light-emitting layer.
Co-reporter:Ming Wang, Xiaowen Hu, Liqian Liu, Chunhui Duan, Peng Liu, Lei Ying, Fei Huang, and Yong Cao
Macromolecules 2013 Volume 46(Issue 10) pp:3950-3958
Publication Date(Web):May 15, 2013
DOI:10.1021/ma400355w
Three donor–acceptor type of narrow band gap conjugated polymers with enlarged coplanar skeleton were synthesized via Stille copolymerization of indacenodithiophene (IDT) and naphtho[1,2-c:5,6-c]bis(1,2,5-thiadiazole) (NT) based monomers. The energy levels, absorption spectra and band gaps of the resulting polymers were well tuned by utilizing different thiophene derivatives as spacer between IDT and NT units, and polymer PIDT-C12NT which employed bithiophene attached with dodecyl side chain as spacer exhibited superior properties compared to the other two copolymers. All polymers exhibited deep highest occupied molecular orbital energy levels and subsequently lead to high open circuit voltages of fabricated solar cell devices. Best performance of the bulk-heterojunction solar cells with a power conversion efficiency of 5.05% was achieved with PIDT-C12NT as donor and (6,6)-phenyl-C71-butyric acid methyl ester (PC71BM) as acceptor, which can be attributed to its higher charge carrier mobility, the optimized interpenetrating network as well as enhanced absorption coefficient of photoactive layer with respect to the other two polymers. The results demonstrated that the combination of IDT and NT with appropriate spacers was a promising molecular design strategy for the application of solar cells.
Co-reporter:Xing Guan;Kai Zhang;Guillermo C. Bazan;Yong Cao
Advanced Functional Materials 2012 Volume 22( Issue 13) pp:2846-2854
Publication Date(Web):
DOI:10.1002/adfm.201200199
Abstract
A series of amino N-oxide functionalized polyfluorene homopolymers and copolymers (PNOs) are synthesized by oxidizing their amino functionalized precursor polymers (PNs) with hydrogen peroxide. Excellent solubility in polar solvents and good electron injection from high work-function metals make PNOs good candidates for interfacial modification of solution processed multilayer polymer light-emitting diodes (PLEDs) and polymer solar cells (PSCs). Both PNOs and PNs are used as cathode interlayers in PLEDs and PSCs. It is found that the resulting devices show much better performance than devices based on a bare Al cathode. The effect of side chain and main chain variations on the device performance is investigated. PNOs/Al cathode devices exhibit better performance than PNs/Al cathode devices. Moreover, devices incorporating polymers with para-linkage of pyridinyl moieties exhibit better performance than those using polymers with meta-linked counterparts. With a poly[(2,7-(9,9-bis(6-(N,N-diethylamino)-hexyl N-oxide)fluorene))-alt-(2,5-pyridinyl)] (PF6NO25Py) cathode interlayer, the resulting device exhibits a luminance efficiency of 16.9 cd A−1 and a power conversion efficiency of 6.9% for PLEDs and PSCs, respectively. These results indicate that PNOs are promising new cathode interlayers for modifying a range of optoelectronic devices.
Co-reporter:Chunhui Duan, Chengmei Zhong, Chunchen Liu, Fei Huang, and Yong Cao
Chemistry of Materials 2012 Volume 24(Issue 9) pp:1682
Publication Date(Web):April 21, 2012
DOI:10.1021/cm300824h
A phosphate group-containing bisadducts fullerene derivative bis-[6,6]-phenyl-C60-pentyl phosphoric diethyl ester (B-PCPO) has been developed as an indium tin oxide (ITO) interlayer material in inverted polymer solar cells. The B-PCPO possessed good alcohol solubility, n-type nature, good electron transporting ability, and ITO modification function simultaneously, and it was utilized as an ITO interlayer in solution-processed multilayer inverted bulk-heterojunction polymer solar cells to improve the electron transporting and collection. It was found that the B-PCPO interlayer could effectively decrease the work function of ITO and thereby enhance the electron collection of ITO electrode. The device studies showed that the resulting solar cells' efficiencies were significantly increased from 4.83% to 6.20% by using a B-PCPO interlayer, benefiting from the dramatic enhancement in open circuit voltage and moderate increase in fill factor. Our results provide a promising approach to improve the performance of inverted polymer solar cells.Keywords: alcohol soluble fullerene derivative; interfacial modification; inverted polymer solar cells; ITO interlayer;
Co-reporter:Jie Zhang, Kai Zhang, Xuelong Huang, Wanzhu Cai, Cheng Zhou, Shengjian Liu, Fei Huang and Yong Cao
Journal of Materials Chemistry A 2012 vol. 22(Issue 25) pp:12759-12766
Publication Date(Web):27 Apr 2012
DOI:10.1039/C2JM31773G
Supramolecular light-emitting polymers (SLEPs) based on host–guest interactions were developed for solution processed organic electronic devices. The dibenzo-24-crown-8 functionalized blue-emitting conjugated oligomer 1 and green-emitting conjugated oligomer 3 were used as the host materials, and the dibenzylammonium salt functionalized blue-emitting conjugated oligomer 2 was used as the guest material. The resulting linear SLEPs were obtained from the self-organization of the host and guest oligomers, which were confirmed by the nuclear magnetic resonance, viscosity and differential scanning calorimetry studies. Highly fluorescent SLEP nanofibers can be easily obtained by drawing or electron-spinning from the equimolar solution of the host and guest oligomers. The photophysical and electroluminescence properties of the resulting SLEPs were fully investigated. It was found that the SLEPs' emission colors can be well tuned from blue to green with significantly enhanced photoluminescent efficiencies by using 3 as the dopant, which is due to the efficient energy transfer caused by the exciton trapping on narrow band gap host oligomer 3 in the SLEPs. As a result, the designed SLEPs showed comparable electroluminescence device performances to those analogous traditional conjugated polymers. Considering the precisely defined starting monomers and catalyst-free polymerization process for the designed SLEPs, combining the good device performances, the present study provides a promising alternative route to develop solution processed semiconductors for optoelectronic applications.
Co-reporter:Chunhui Duan, Fei Huang and Yong Cao
Journal of Materials Chemistry A 2012 vol. 22(Issue 21) pp:10416-10434
Publication Date(Web):09 Mar 2012
DOI:10.1039/C2JM30470H
Bulk-heterojunction polymer solar cells have emerged as an attractive type of cost-effective solar energy–electrical power transforming device. Recently, great progress in the development of new photo-harvesting materials and device optimizations have been achieved in this field, resulting in the significant improvement of the power conversion efficiencies of polymer solar cells from around 1% to higher than 8.0%. The rational design and fine tailoring of the molecular structures of donor polymers significantly contributed to these prominent advances. Among all kinds of donor polymers, push–pull conjugated polymers, which consist of alternating electron-rich and electron-deficient units have been most extensively developed and have dominated the library of donor materials for polymer solar cells, because their intrinsic optical and electronic properties can be readily tuned to the desired situation by controlling the intramolecular charge transfer from donor unit to acceptor unit. This review provides a brief overview of the recent development of push–pull conjugated polymers and their application in solar cells. The relationships between the materials' chemical structures and properties, such as absorption spectra, energy levels, mobilities and photovoltaic behaviors, were also discussed.
Co-reporter:Charlie C. D. Wang, Wallace C. H. Choy, Chunhui Duan, Dixon D. S. Fung, Wei E. I. Sha, Feng-Xian Xie, Fei Huang and Yong Cao
Journal of Materials Chemistry A 2012 vol. 22(Issue 3) pp:1206-1211
Publication Date(Web):18 Nov 2011
DOI:10.1039/C1JM14150C
The effects of Au nanoparticles (NPs) incorporated into the active layer of polymer solar cells (PSCs) with a newly synthesized donor polymer are investigated in detail. Our work shows that localized surface plasmon resonance (LSPR) introduced by the metallic NPs can experimentally and theoretically enhance the light absorption in the active layer of PSCs because the strong LSPR near field mainly distributes laterally along the active layer. The understanding can be applied to other metallic NP incorporated organic solar cells. Meanwhile, our results show that electrical properties can counter-diminish the optical enhancement from LSPR and thus reduce the overall performance improvement. It is important that both optical and electrical properties need to be studied and optimized simultaneously for achieving improved power conversion efficiency. The study contributes to better understanding the uses of Au NPs for enhancing PSC performances.
Co-reporter:Mingliang Sun, Xi Jiang, Wei Liu, Tongbo Zhu, Fei Huang, Yong Cao
Synthetic Metals 2012 Volume 162(15–16) pp:1406-1410
Publication Date(Web):September 2012
DOI:10.1016/j.synthmet.2012.06.006
A series of random low band-gap conjugated copolymers (PFO-DDSTQ) derived from 9,9-dioctylfluorene (DOF) and 6,7-dimethyl-4,9-di(selenophen-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline (DDSTQ) are prepared by the palladium-catalyzed Suzuki coupling reaction. The obtained polymers are readily soluble in common organic solvents. The polymers absorb light from 300 to 880 nm with two absorbance peaks at around 370 and 740 nm. The optical band gaps of the resulting polymers with 15 or 30% narrow band-gap units in the polymer backbone calculated from the absorption onset are around 1.41 eV. The electroluminescent properties of the polymers were investigated and it was found that with 5% DDSTQ copolymerized on the main chain, the resulting polymer PFO-DDSTQ5 exhibited an exclusively near-infrared emission at 860 nm.Graphical abstractHighlights► Selenophene and fluorene based narrow band gap copolymers with Eg = 1.41 eV is synthesized. ► The polymer based near infrared polymer light emitting diodes (NIPLEDs) show electroluminescence peak at 860 nm. ► The electroluminescence spectrum match telecommunications wavelength 0.8–0.9 μm. ► This is the first report about selenophene based NIPLEDs in 0.8–0.9 μm.
Co-reporter:Kai Zhang;ShengJian Liu;Xing Guan;ChunHui Duan;Jie Zhang
Science China Chemistry 2012 Volume 55( Issue 5) pp:766-771
Publication Date(Web):2012 May
DOI:10.1007/s11426-012-4530-0
A series of alkali metal salts doped pluronic block copolymer F127 were used as electron injection/transport layers (ETLs) for polymer light-emitting diodes with poly[2-(4-(3′,7′-dimethyloctyloxy)-phenyl)-p-phenylenevinylene] (P-PPV) as the emission layer. It was found that the electron transport capability of F127 can be effectively enhanced by doping with alkali metal salts. By using Li2CO3 (15%) doped F127 as ETL, the resulting device exhibited improved performance with a maximum luminous efficiency (LE) of 13.59 cd/A and a maximum brightness of 5529 cd/m2, while the device with undoped F127 as ETL only showed a maximum LE of 8.78 cd/A and a maximum brightness of 2952 cd/m2. The effects of the doping concentration, cations and anions of the alkali metal salts on the performance of the resulting devices were investigated. It was found that most of the alkali metal salt dopants can dramatically enhance the electron transport capability of F127 ETL and the performance of the resulting devices was greatly improved.
Co-reporter:Yang Dong, Wanzhu Cai, Xiaowen Hu, Chengmei Zhong, Fei Huang, Yong Cao
Polymer 2012 Volume 53(Issue 7) pp:1465-1472
Publication Date(Web):22 March 2012
DOI:10.1016/j.polymer.2012.02.014
Two novel conjugated alternating copolymers with [1,2,5]thiadiazolo[3,4-f]benzotriazole as acceptor and 9,9-dioctylfluorene or N-9’-heptadecanyl-carbazole as donors respectively, were synthesized by Suzuki polycondensation. Both of the two copolymers have nearly ideal band gaps and show excellent absorption spectra in near infrared region. Polymer solar cells based on the blends of them and [6,6]-phenyl-C71 butyric acid methyl ester show excellent performance when using a water/alcohol soluble conjugated polymer as cathode interlayer, which exhibit a maximum power conversion efficiency of 3.17% with the short-circuit current density of 8.50 mA/cm2, the open-circuit voltage of 0.70 V and the fill factor of 41%. Our results demonstrate that [1,2,5]thiadiazolo[3,4-f]benzotriazole is a promising acceptor unit for low band gap polymer donor materials design.
Co-reporter:Hongmei Xie, Kai Zhang, Chunhui Duan, Shengjian Liu, Fei Huang, Yong Cao
Polymer 2012 Volume 53(Issue 25) pp:5675-5683
Publication Date(Web):30 November 2012
DOI:10.1016/j.polymer.2012.10.008
A series of new acceptor-pended conjugated polymers P27CZSDCN, P27CZSDTA, P36CZSDCN and P36CZSDTA, which are composed of carbazole and triphenylamine alternatingly arranged main chain, electron-withdrawing pendant groups (malononitrile and 1,3-diethyl-2-thiobarbituric acid) and thiophene π-bridge, are designed and synthesized. Both 2,7-carbazole and 3,6-carbazole are used as the building blocks to tune conjugation length and charge transfer properties of the resulting polymers. The relationships between chemical structure and optoelectronic properties of the polymers were systematically investigated. It was found that the 3,6-carbazole-derived polymers exhibited blue-shifted absorption at the short wavelength region and lower hole mobility compared to their 2,7-carbazole-derived analogues because of the conjugation breaks induced by 3,6-carbazole units. Moreover, the 3,6-carbazole-derived polymers exhibited much enhanced and slightly red-shifted intramolecular charge transfer absorption at the long wavelength region, as well as lower oxidation potential with respect to their 2,7-carbazole-derived analogues, possibly being caused by the more efficient electron-donating capability of nitrogen atoms on 3,6-carbazole units. The photovoltaic properties of the resulting polymers are studied by blending the polymers with (6,6)-phenyl-C71-butyric acid methyl ester. The highest power conversion efficiencies of 2.47% and 1.69% are achieved for 2,7-carbazole-derived polymers and 3,6-carbazole-derived polymers, respectively.Graphical abstract
Co-reporter:Chunhui Duan, Xiaowen Hu, Kung-Shih Chen, Hin-Lap Yip, Wei Li, Fei Huang, Alex K.-Y. Jen, Yong Cao
Solar Energy Materials and Solar Cells 2012 97() pp: 50-58
Publication Date(Web):
DOI:10.1016/j.solmat.2011.08.028
Co-reporter:Chunhui Duan;Lei Wang;Kai Zhang;Xing Guan
Advanced Materials 2011 Volume 23( Issue 14) pp:1665-1669
Publication Date(Web):
DOI:10.1002/adma.201004661
Co-reporter:Ming Wang ; Xiaowen Hu ; Peng Liu ; Wei Li ; Xiong Gong ; Fei Huang ;Yong Cao
Journal of the American Chemical Society 2011 Volume 133(Issue 25) pp:9638-9641
Publication Date(Web):June 1, 2011
DOI:10.1021/ja201131h
Donor–acceptor conjugated polymers PBDT-DTBT and PBDT-DTNT, based on 2,1,3-benzothiadiazole (BT) and naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole (NT), have been designed and synthesized for polymer solar cells. NT contains two fused 1,2,5-thiadiazole rings that lower the band gap, enhance the interchain packing, and improve the charge mobility of the resulting polymer. Consequently, the NT-based polymer PBDT-DTNT exhibited considerably better photovoltaic performance with a power conversion efficiency (PCE) of 6.00% when compared with the BT-based polymer PBDT-DTBT, which gave a PCE of 2.11% under identical device configurations.
Co-reporter:Chengmei Zhong, Chunhui Duan, Fei Huang, Hongbin Wu, and Yong Cao
Chemistry of Materials 2011 Volume 23(Issue 3) pp:326
Publication Date(Web):October 21, 2010
DOI:10.1021/cm101937p
Organic light-emitting diodes (OLEDs) have been successfully developed and have now entered the commercial marketplace. Besides the impressive performance as displays, one of the key advantages of OLEDs is that they can potentially be made entirely by solution process and thus are more suitable for low cost, large area flexible displays and white lighting panels. To realize this, many efforts have been devoted on the development of solution processable light-emitting materials and charge transporting materials as well as electrode materials, which have resulted in the successful demonstration of high performance fully solution processed OLEDs and have opened a way to achieve all printable roll-to-roll organic optoelectronic devices.
Co-reporter:Chengmei Zhong, Shengjian Liu, Fei Huang, Hongbin Wu, and Yong Cao
Chemistry of Materials 2011 Volume 23(Issue 21) pp:4870
Publication Date(Web):October 17, 2011
DOI:10.1021/cm2025685
We show that a series of solution processable and cross-linkable amino-functionalized polyfluorene materials can effectively enhance the electron injection from the indium tin oxide (ITO) electrodes, and for the first time, highly efficient inverted organic light emitting devices are fabricated using cross-linkable conjugated polymers as a single electron injection layer without the need for n-type metal oxide layers. The mechanism for the electron injection enhancement effect of the ITO/cross-linkable conjugated polymer interface is studied by X-ray photoelectron spectroscopy, Kelvin probe, and photovoltaic measurement. It was found that the amino groups among these polymers can effectively lower the work function of ITO, which will greatly enhance the electron injection in the resulting devices.Keywords: cross-linkable conjugated polymers; electron injection layer; inverted structure; organic light-emitting diodes;
Co-reporter:ShengJian Liu;ChengMei Zhong;Jie Zhang;ChunHui Duan
Science China Chemistry 2011 Volume 54( Issue 11) pp:1745-1749
Publication Date(Web):2011 November
DOI:10.1007/s11426-011-4386-8
A novel crosslinkable water/alcohol soluble conjugated polymer PFN-C containing oxetane groups and aminoalkyl groups in the side chains has been developed and used as highly efficient electron injection and transporting material for polymer light-emitting diodes (PLEDs). The unique solubility in polar solvents and crosslinkable ability of PFN-C render it a good candidate for solution processed multilayer PLEDs. It was found that PFN-C can greatly enhance the electron injection from high work-function metal cathode, due to its pendant amino groups. As a result, PLEDs with PFN-C/Al cathode exhibited comparable device performance to the devices with Ba/Al cathode. The resulting green light-emitting device showed promising performance with a maximum luminance efficiency of 13.53 cd A−1.
Co-reporter:Jie Zhang, Wanzhu Cai, Fei Huang, Ergang Wang, Chengmei Zhong, Shengjian Liu, Ming Wang, Chunhui Duan, Tingbin Yang, and Yong Cao
Macromolecules 2011 Volume 44(Issue 4) pp:894-901
Publication Date(Web):January 27, 2011
DOI:10.1021/ma1027164
A series of narrow-band-gap donor−acceptor (D−A) conjugated polymers, with thiophene-substituted quinoxaline monomer 5,8-bis(5-bromothiophen-2-yl)-2,3-bis(5-octylthiophen-2-yl)quinoxaline (TTQx) or its cyclized phenazine derivative monomer 8,11-bis(5-bromothiophen-2-yl)-2,5-dioctyldithieno[2,3-a:3′,2′-c]phenazine (TTPz) as acceptors, were synthesized via Suzuki coupling reaction. It was found that the copolymers based on thiophene-substituted quinoxaline TTQx exhibit obviously red-shifted absorbance compared to previously reported D−A copolymers based on phenyl-substituted quinoxaline. Their analogous copolymers based on the cyclized TTPz acceptor show more pronounced red-shifted absorption spectra with a significantly decreased band gap due to the enlarged planar polycyclic aromatic ring of TTPz. Moreover, compared to the copolymers based on TTQx, the TTPz-based copolymers’ mobilities are also significantly increased due to the reduced steric hindrance and improved structural planarity among the copolymers. Bulk-heterojunction polymer solar cells based on the blends of the copolymers with a fullerene derivative as an acceptor exhibit promising performance, and the best device performance with power conversion efficiency up to 4.4% was achieved.
Co-reporter:ChunHui Duan;ChuanDao Wang;ShengJian Liu
Science China Chemistry 2011 Volume 54( Issue 4) pp:685-694
Publication Date(Web):2011 April
DOI:10.1007/s11426-011-4257-3
Three two-dimensional like conjugated copolymers PFSDCN, PFSDTA and PFSDCNIO, which consist of alternating fluorene and triphenylamine main chain, and different pendant acceptor groups (malononitrile, 1,3-diethtyl-2-thiobarbituric acid and 2-(1,2-dihydro-1-oxoinden-3-ylidene)malononitrile) with thiophene as π-bridge, have been designed, synthesized and characterized. The structure-property relationships of the two-dimensional like conjugated copolymers were systematically investigated. The absorption spectra, band gaps, and energy levels of the polymers were effectively tuned by simply attaching different acceptor groups. As the electron-withdrawing ability of the acceptors increased, the band gaps of the polymers were narrowed from 2.05 to 1.61 eV; meanwhile, the LUMO energy levels of the polymers decreased from −3.27 to −3.75 eV, whereas their relatively deep HOMO energy levels of ∼−5.35 eV were preserved. BHJ solar cells were fabricated and characterized by using the three polymers as donor materials and the highest power conversion efficiency of 2.87% was achieved for the device based on PFSDTA:(6,6)-phenyl-C71-butyric acid methyl ester blend.
Co-reporter:Fei Huang, Hongbin Wu and Yong Cao
Chemical Society Reviews 2010 vol. 39(Issue 7) pp:2500-2521
Publication Date(Web):10 Mar 2010
DOI:10.1039/B907991M
Water/alcohol soluble conjugated polymers (WSCPs) can be processed from water or other polar solvents, which offer good opportunities to avoid interfacial mixing upon fabrication of multilayer polymer optoelectronic devices by solution processing, and can dramatically improve charge injection from high work-function metal cathode resulting in greatly enhancement of the device performance. In this critical review, the authors provide a brief review of recent developments in this field, including the materials design, functional principles, and their unique applications as interface modification layer in solution-processable multilayer optoelectronic devices (135 references).
Co-reporter:Chunhui Duan, Kung-Shih Chen, Fei Huang, Hin-Lap Yip, Shengjian Liu, Jie Zhang, Alex K.-Y. Jen, and Yong Cao
Chemistry of Materials 2010 Volume 22(Issue 23) pp:6444
Publication Date(Web):November 8, 2010
DOI:10.1021/cm1027157
A series of carbazole-based narrow-band gap polymers with two-dimensional donor-π-bridge-acceptor (D-π-A) structures were synthesized and characterized for use in polymer bulk heterojunction solar cells. These D-π-A side-chain polymers were obtained through the Knoevenagel condensation between the aldehyde-containing precursor polymers and the corresponding acceptors. The resulting polymers have good solubility in common organic solvents and excellent thermal properties. The effects of the alkyl side chains and different dye contents on optical properties, electronic structures, charge-transporting ability, and device performance of these polymers were investigated. By blending these polymers as light-harvesting electron donors with (6,6)-phenyl-C71-butyric acid methyl ester (PC71BM) electron acceptors in bulk heterojunction solar cells, high power conversion efficiency (PCE), as high as 4.47%, could be achieved.
Co-reporter:Chunhui Duan, Wanzhu Cai, Fei Huang, Jie Zhang, Ming Wang, Tingbin Yang, Chengmei Zhong, Xiong Gong and Yong Cao
Macromolecules 2010 Volume 43(Issue 12) pp:5262-5268
Publication Date(Web):May 19, 2010
DOI:10.1021/ma100616f
Two low-band-gap conjugated polymers, PSiFDCN and PSiFDTA, which consist of alternating silafluorene and triphenylamine backbone and different pendant acceptor groups (malononitrile and 1,3-diethyl-2-thiobarbituric acid) with styrylthiophene as π-bridge, were synthesized and characterized. By changing the acceptor groups in side chain, the energy levels, absorption spectra, and band gaps of the resulted polymers were effectively tuned. As the strength of the acceptors increases, the band gap reduces from 1.83 eV for PSiFDCN to 1.74 eV for PSiFDTA. Bulk heterojunction solar cells with these polymers as electron donor and (6,6)-phenyl-C71-butyric acid methyl ester (PC71BM) as electron acceptor exhibit high Voc (>0.85 V) and power conversion efficiency (PCE) of 2.50% and 3.15% for PSiFDCN and PSiFDTA, respectively.
Co-reporter:Kai Zhang, Rongguo Xu, Wenjiao Ge, Meng Qi, Guangzhao Zhang, Qing-Hua Xu, Fei Huang, Yong Cao, Xiaohui Wang
Nano Energy (April 2017) Volume 34() pp:
Publication Date(Web):April 2017
DOI:10.1016/j.nanoen.2017.02.022
•Chitosan was used as cathode interlayer material in inverted organic solar cell by integrating self-assembly techniques.•The self-assembly process formed chitosan films were quite flat and uniform with controlled thickness on a nanometer scale.•Due to the highly ordered layer-by-layer chitosan films, both interfacial dipoles and molecular dipoles were formed.•With the modification of chitosan eLbL films, inverted OSCs exhibited power conversion efficiency (PCE) of 10.18%.In this work, we employed chitosan, which is the second most abundant biomass on earth after cellulose, and its derivatives as cathode interlayer (instead of substrate) materials in inverted organic solar cells (OSCs) by employing electrostatic Layer-by-Layer (eLbL) self-assembly technique. It was found that the eLbL self-assembly technique was a suitable strategy to obtain continuous films with full surface coverage, uniformity and controlled thickness under nanometer scale. What's more, due to the highly ordered layer-by-layer structure, both interfacial dipoles and molecular dipoles were formed and utilized to decrease the work function of the electrode and enhance device performance. With optimized chitosan eLbL films as cathode interlayer, inverted OSCs exhibited a power conversion efficiency (PCE) of 9.34%, which was approximately a 200% improvement over cells with no cathode interlayer. Moreover, the chitosan eLbL films can be utilized to improve the PCE of thick active layer (210 nm) OSCs to 10.18%.Chitosan and its derivatives were used as cathode interlayer materials in inverted organic solar cells (OSCs) by integrating electrostatic Layer-by-Layer (eLbL) self-assembly techniques. With the modification of chitosan eLbL films, inverted OSCs exhibited power conversion efficiency (PCE) of 9.34% with 100 nm active layer and 10.18% with 210 nm active layer.
Co-reporter:Kai Zhang ; Chengmei Zhong ; Shengjian Liu ; Cheng Mu ; Zhengke Li ; He Yan ; Fei Huang ;Yong Cao
ACS Applied Materials & Interfaces () pp:
Publication Date(Web):
DOI:10.1021/am501920z
A cross-linkable water/alcohol soluble conjugated polymer (WSCP) material poly[9,9-bis(6′-(N,N-diethylamino)propyl)-fluorene-alt-9,9-bis(3-ethyl(oxetane-3-ethyloxy)-hexyl) fluorene] (PFN-OX) was designed. The cross-linkable nature of PFN-OX is good for fabricating inverted polymer solar cells (PSCs) with well-defined interface and investigating the detailed working mechanism of high-efficiency inverted PSCs based on poly[4,8-bis(2-ethylhexyloxyl)benzo[1,2-b:4,5-b′]dithio-phene-2,6-diyl-alt-ethylhexyl-3-fluorothithieno[3,4-b]thiophene-2-carboxylate-4,6-diyl] (PTB7) and (6,6)-phenyl-C71-butyric acid methyl ester (PC71BM) blend active layer. The detailed working mechanism of WSCP materials in high-efficiency PSCs were studied and can be summarized into the following three effects: a) PFN-OX tunes cathode work function to enhance open-circuit voltage (Voc); b) PFN-OX dopes PC71BM at interface to facilitate electron extraction; and c) PFN-OX extracts electrons and blocks holes to enhance fill factor (FF). On the basis of this understanding, the hole-blocking function of the PFN-OX interlayer was further improved with addition of a ZnO layer between ITO and PFN-OX, which led to inverted PSCs with a power conversion efficiency of 9.28% and fill factor high up to 74.4%.
Co-reporter:Jie Zhang, Kai Zhang, Xuelong Huang, Wanzhu Cai, Cheng Zhou, Shengjian Liu, Fei Huang and Yong Cao
Journal of Materials Chemistry A 2012 - vol. 22(Issue 25) pp:NaN12766-12766
Publication Date(Web):2012/04/27
DOI:10.1039/C2JM31773G
Supramolecular light-emitting polymers (SLEPs) based on host–guest interactions were developed for solution processed organic electronic devices. The dibenzo-24-crown-8 functionalized blue-emitting conjugated oligomer 1 and green-emitting conjugated oligomer 3 were used as the host materials, and the dibenzylammonium salt functionalized blue-emitting conjugated oligomer 2 was used as the guest material. The resulting linear SLEPs were obtained from the self-organization of the host and guest oligomers, which were confirmed by the nuclear magnetic resonance, viscosity and differential scanning calorimetry studies. Highly fluorescent SLEP nanofibers can be easily obtained by drawing or electron-spinning from the equimolar solution of the host and guest oligomers. The photophysical and electroluminescence properties of the resulting SLEPs were fully investigated. It was found that the SLEPs' emission colors can be well tuned from blue to green with significantly enhanced photoluminescent efficiencies by using 3 as the dopant, which is due to the efficient energy transfer caused by the exciton trapping on narrow band gap host oligomer 3 in the SLEPs. As a result, the designed SLEPs showed comparable electroluminescence device performances to those analogous traditional conjugated polymers. Considering the precisely defined starting monomers and catalyst-free polymerization process for the designed SLEPs, combining the good device performances, the present study provides a promising alternative route to develop solution processed semiconductors for optoelectronic applications.
Co-reporter:Shengjian Liu, Guichuan Zhang, Junming Lu, Jianchao Jia, Wei Li, Fei Huang and Yong Cao
Journal of Materials Chemistry A 2015 - vol. 3(Issue 17) pp:NaN4379-4379
Publication Date(Web):2015/03/24
DOI:10.1039/C5TC00452G
A small-molecule amino-functionalized organoplatinum(II) complex Pt–N has been developed. The unique properties of Pt–N, including a well-defined chemical structure, an excellent solubility in environmentally friendly polar solvents and good electron extraction to high work-function metals, make it a promising candidate for cathode interfacial modification of solution processed multilayer polymer solar cells (PSCs). The resultant PSCs with an ITO/PEDOT:PSS/PTB7:PC71BM/interlayer/Al device configuration exhibited significantly improved efficiencies from 3.62% for an unmodified device to 8.89% by using a Pt–N cathode interlayer, benefiting from the dramatic enhancement in the open circuit voltage (0.53 V for bare Al PSCs to 0.75 V for Pt–N/Al PSCs), the fill factor (43.58% for bare Al PSC to 72.49% for Pt–N/Al PSC), and a slight increase in short-circuit current density. These results indicate that Pt–N is a new promising candidate as the cathode interlayer for highly efficient PSCs.
Co-reporter:Xi Liu, Rongguo Xu, Chunhui Duan, Fei Huang and Yong Cao
Journal of Materials Chemistry A 2016 - vol. 4(Issue 19) pp:NaN4295-4295
Publication Date(Web):2016/04/07
DOI:10.1039/C6TC00906A
A series of non-conjugated water/alcohol soluble copolymers containing diphenyl sulfide, diphenyl sulfoxide or diphenyl sulfone in the main chain were synthesized. The surfactant-like functionalities in side chains endow the polymers with outstanding solubility in highly polar solvents and excellent electron extraction abilities, while the limited conjugation length of main chains renders the polymers weak optical absorption. These unique characteristics make the polymers excellent cathode interfacial layers, which contribute to highly efficient polymer solar cells (PSCs) with power conversion efficiencies of 8–9%. More importantly, some of them can yield highly efficient PSCs in a relative large interlayer thickness range of 2–20 nm. The results suggest that these polymers are promising candidates for use as cathode interfacial layers in single-junction PSCs and as recombination layers in multi-junction PSCs.
Co-reporter:Zuosheng Peng, Yangdong Zhang, Yuxin Xia, Kang Xiong, Chaosheng Cai, Lianpeng Xia, Zhanhao Hu, Kai Zhang, Fei Huang and Lintao Hou
Journal of Materials Chemistry A 2015 - vol. 3(Issue 41) pp:NaN20507-20507
Publication Date(Web):2015/09/03
DOI:10.1039/C5TA06009E
We report a facile technique of blending a conjugated polymer thieno[3,4-b]thiophene/benzodithiophene (PTB7):[6,6]-phenyl-C71-butyric acid methyl ester (PCBM[70]) active materials with a conjugated interfacial modification polymer poly[(9,9-bis(3′-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN) to simplify the coating process and improve the bulk heterojunction (BHJ) polymer solar cell (PSC) performance. The reason for and result of PFN self-organization via a spontaneous vertical delamination onto the ITO surface were investigated by charge transfer state, optical modelling based on transfer matrix formalism, surface energy measurement, scanning Kelvin probe force microscopy and impedance spectroscopy analysis in conjunction with atomic force microscopy and scanning electron microscopy. The relaxed charge transfer state demonstrates that PFN doping has a negligible impact on the donor:acceptor heterojunction interface. The optical simulation of device structures indicates that doping PFN into a BHJ has nearly no influence on the photon absorption profile of the active layer. Very encouraging device performance was achieved in the one-step coating PFN:BHJ PSC with ITO as the cathode, which is comparable to that of the two-step coating PSC. Moreover, for ITO-free inverted PSCs with PEDOT:PSS as the incident light top-electrode, decent device performance can also be obtained, demonstrating the remarkable universality through this facile strategy.
Co-reporter:Qin Hu, Yi Liu, Yu Li, Lei Ying, Tanghao Liu, Fei Huang, Shufeng Wang, Wei Huang, Rui Zhu and Qihuang Gong
Journal of Materials Chemistry A 2015 - vol. 3(Issue 36) pp:NaN18491-18491
Publication Date(Web):2015/08/04
DOI:10.1039/C5TA04695E
A cross-linkable conjugated polymer, poly[9,9-bis(6′-(N,N-diethylamino)propyl)-fluorene-alt-9,9-bis-(3-ethyl(oxetane-3-ethyloxy)-hexyl)-fluorene] (PFN-OX), was investigated as the n-type interface layer for highly efficient and low-temperature processed planar heterojunction perovskite solar cells. Hybrid composite films consisting of PFN-OX and ZnO nanoparticles were utilized as electron selective layers, and a remarkable power conversion efficiency over 16% was achieved. The cross-linkable PFN-OX provided a robust hybrid composite electron selective layer, which is solvent-resistant during the device fabrication process and results in efficient electron extraction and hole blocking. Meanwhile, time-resolved photoluminescence quenching measurements indicated that the charge separation and collection processes were improved for devices based on PFN-OX:ZnO, in comparison with devices using pure PFN-OX or ZnO. The device stability and the hysteresis effect were also discussed. Moreover, this study introduces the cross-linking concept in perovskite solar cells, which will potentially be an effective strategy for obtaining high performance perovskite solar cells.
Co-reporter:Fei Huang, Hongbin Wu and Yong Cao
Chemical Society Reviews 2010 - vol. 39(Issue 7) pp:NaN2521-2521
Publication Date(Web):2010/03/10
DOI:10.1039/B907991M
Water/alcohol soluble conjugated polymers (WSCPs) can be processed from water or other polar solvents, which offer good opportunities to avoid interfacial mixing upon fabrication of multilayer polymer optoelectronic devices by solution processing, and can dramatically improve charge injection from high work-function metal cathode resulting in greatly enhancement of the device performance. In this critical review, the authors provide a brief review of recent developments in this field, including the materials design, functional principles, and their unique applications as interface modification layer in solution-processable multilayer optoelectronic devices (135 references).
Co-reporter:Chunhui Duan, Kai Zhang, Xing Guan, Chengmei Zhong, Hongmei Xie, Fei Huang, Junwu Chen, Junbiao Peng and Yong Cao
Chemical Science (2010-Present) 2013 - vol. 4(Issue 3) pp:NaN1307-1307
Publication Date(Web):2013/01/08
DOI:10.1039/C3SC22258F
A series of new water/alcohol-soluble conjugated polymers (WSCPs) poly[(9,9-bis((N-(4-sulfonate-1-butyl)-N,N-dimethylammonium)propyl)-2,7-fluorene)-alt-N-phenyl-4,4′-diphenylamine)] (PFNSO-TPA), poly[(9,9-bis((N-(4-sulfonate-1-butyl)-N,N-dimethylammonium)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFNSO) and poly[(9,9-bis((N-(4-sulfonate-1-butyl)-N,N-dimethylammonium)propyl)-2,7-fluorene)-alt-4,7-(2,1,3-benzothiadiazole)] (PFNSO-BT), comprising identical sulfobetaine zwitterionic groups on their side chains but different conjugated main chain structures, were designed and developed as interface modification materials to improve electron collection in bulk-heterojunction polymer solar cells (PSCs), and to improve electron injection/transporting in polymer light-emitting diodes (PLEDs). The resulting WSCPs possess integrated advantages of excellent alcohol processability, interface modification functions and mobile ion free nature. The relationships between the WSCPs main chain structures and properties (including optical/electrical properties and interface modification functions in resulting devices) were investigated systematically. In PSCs, it was found that the WSCPs interface modification properties led to varying differences, but all of them can boost the photovoltaic performances of PSCs; encouragingly, a high power conversion efficiency (PCE) of 8.74% could be achieved. In PLEDs, the interface modification functions of the WSCPs strongly depend upon their conjugated main chain structures. The WSCPs should possess suitable energy levels to match well with the light-emitting layer (EML), even though the electron injection from metal cathode was efficient. Our results show promising potentials of WSCPs as interface modification layers in organic/polymer optoelectronic devices, and provide new insights for the development of new interface modification materials in the future.
Co-reporter:Jie Zhang, Sheng Dong, Kai Zhang, Aihui Liang, Xiye Yang, Fei Huang and Yong Cao
Chemical Communications 2014 - vol. 50(Issue 60) pp:NaN8230-8230
Publication Date(Web):2014/06/05
DOI:10.1039/C4CC03080J
A series of blue supramolecular polymers with different counterions based on host–guest interactions were developed for polymer light-emitting diodes. It was found that the counterions play important roles in the resulting materials' supramolecular interactions as well as the device performance.
Co-reporter:Liqian Liu, Guichuan Zhang, Baitian He, Shengjian Liu, Chunhui Duan and Fei Huang
Inorganic Chemistry Frontiers 2017 - vol. 1(Issue 3) pp:NaN506-506
Publication Date(Web):2016/08/31
DOI:10.1039/C6QM00130K
The field of polymer solar cells has undergone tremendous advancement in terms of power conversion efficiency in the past decade. However, there is still an urgent requirement to further enhance device performance for achieving large-scale commercialization. Here, we report the design and synthesis of three novel conjugated polymers alternatively copolymerized by a newly developed 2,3,8,9-tetrakis(3-(alkoxy)phenyl)-6,12-di(thiophen-2-yl)-2,3,8,9-tetrahydroquinoxalino[6,5-f]quinoxaline (DTNQx) acceptor unit and a conventional two-dimensional alkylthienyl-substituted benzodithiophene (BDT) unit. These polymers possess an identical main chain but different side chains. The structure–property relationship is systematically studied. All polymers exhibit an optical bandgap around 1.7 eV and a HOMO energy level around −5.16 eV. Compared with the quinoxaline unit, fused quinoxaline DTNQx leads to a downshifted HOMO energy level in the resulting polymers by 0.04 eV while keeping the bandgap unchanged. By changing the side chain length and by introducing branched side chains, polymer properties including absorption spectra and hole mobilities could be finely tuned. Under optimal conditions, polymer P2 shows the highest hole mobility of 2.7 × 10−4 cm2 V−1 s−1 and the best photovoltaic performance, with Jsc = 9.1 mA cm−2, Voc = 0.88 V, FF = 48%, and PCE = 3.8%.
Co-reporter:Kai Zhang, Chengmei Zhong, Shengjian Liu, Ai-hui Liang, Sheng Dong and Fei Huang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 17) pp:NaN3277-3277
Publication Date(Web):2013/11/11
DOI:10.1039/C3TC32022G
Highly efficient inverted white organic light emitting diodes (IWOLEDs) were achieved by a simple solution processing technique, in which cross-linkable amino-functionalized polyfluorene poly[9,9-bis(6′-(N,N-diethylamino)hexyl)-fluorene-alt-9,9-bis(3-ethyl(oxetane-3-ethyoxy)-hexyl)-fluorene] (PFN-OX) served as electron injection/transporting layer (EIL) deposited onto indium tin oxide (ITO) directly without n-type inorganic metal oxides (MOs). The light emitting layer consisted of a (poly(N-vinylcarbazole) (PVK)/1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl]phenylene (OXD-7) blend as host and phosphorescent iridium complexes as guests. Our results demonstrated that ITO could serve as cathode and inject electrons into the phosphorescent system directly and efficiently by using PFN-OX as single EIL. As a result, a high performance IWOLED device with Commission Internationale de L'Eclairage (CIE) coordinate of (0.35, 0.45), colour rendering index (CRI) of 70, maximum luminous efficiency (LE) of 18.1 cd A−1 and maximum power efficiency (PE) of 6.6 lm W−1 was achieved. This result provides an easy way of fabricating multilayer solution processed high efficiency IWOLEDs.
Co-reporter:Aihui Liang, Gui Huang, Sheng Dong, Xiaoyan Zheng, Jia Zhu, Zhiping Wang, Wenjin Wu, Jie Zhang and Fei Huang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 27) pp:NaN6633-6633
Publication Date(Web):2016/06/13
DOI:10.1039/C6TC01922F
We have designed two novel yellow phosphorescent iridium complexes with triphenylamine- and fluorene-functionalized cyclometalating ligands that are capable of producing highly efficient yellow and white polymer light-emitting devices (PLEDs). Both yellow and white-light-emission devices are achieved with an identical single-emission-layer configuration of ITO/PEDOT:PSS/emission layer (EML)/CsF/Al. For the yellow phosphorescent PLEDs based on Y1, the best device performances with a peak luminous efficiency (LE) of 15.1 cd A−1 and a peak external quantum efficiency (EQE) of 7.6% are achieved. More importantly, the two-emitting-component WPLEDs containing iridum(III)bis(2-(4,6-difluorophenyl)-pyridinato-N,C2′) picolinate (FIrpic) as blue and Y1 as yellow phosphors doped into a PVK:OXD-7 matrix at an appropriate ratio exhibited a maximum LE of 14.7 cd A−1, a maximum EQE of 8.6%, a maximum luminance of 5586 cd m−2 and Commission Internationale de L'Eclairage (CIE) coordinates of (0.33, 0.42) which are close to the standard for white light emission. Moreover, at a luminance for practical application of 1000 cd m−2, a good forward viewing LE of 14.4 cd A−1 is obtained with a very slight decrease.
Co-reporter:Yunping Huang, Nannan Zheng, Zhenfeng Wang, Lei Ying, Fei Huang and Yong Cao
Chemical Communications 2017 - vol. 53(Issue 12) pp:NaN2000-2000
Publication Date(Web):2017/01/18
DOI:10.1039/C6CC09317E
Regioregular polymers based on an asymmetric dithieno[3,2-b:2′,3′-d]pyridin-5(4H)-one (TN) unit that consists of a lactam moiety were synthesized via palladium-catalyzed direct heteroarylation polymerization. The random orientation of the lactam moiety can be prevented by carefully designing the monomers with tailored molecular structures. It is noted that connecting the TN unit in different fashions generates substructures in the polymer backbone with different electronic structures. Compared to the random counterparts, the regioregular homopolymers exhibit dramatically discrepant optical properties and electronic structures, while the variations in the copolymers are less distinguished.
Co-reporter:Dan Li, Chen Sun, Hao Li, Hui Shi, Xuxia Shai, Qiang Sun, Junbo Han, Yan Shen, Hin-Lap Yip, Fei Huang and Mingkui Wang
Chemical Science (2010-Present) 2017 - vol. 8(Issue 6) pp:NaN4594-4594
Publication Date(Web):2017/04/19
DOI:10.1039/C7SC00077D
In this study, for the first time, we report a solution-processed amino-functionalized copolymer semiconductor (PFN-2TNDI) with a conjugated backbone composed of fluorine, naphthalene diimide, and thiophene spacers as the electron transporting layer (ETL) in n–i–p planar structured perovskite solar cells. Using this copolymer semiconductor in conjunction with a planar n–i–p heterojunction, we achieved an unprecedented efficiency of ∼16% under standard illumination test conditions. More importantly, the perovskite devices using this polymer ETL have shown good stability under constant ultra violet (UV) light soaking during 3000 h of accelerated tests. Various advanced spectroscopic characterizations, including ultra-fast spectroscopy, ultra-violet photoelectron spectroscopy and electronic impedance spectroscopy, elucidate that the interaction between the functional polymer ETL and the perovskite layer plays a critical role in trap passivation and thus, the device UV-photostability. We expect that these results will boost the development of low temperature solution-processed organic ETL materials, which is essential for the commercialization of high-performance and stable, flexible perovskite solar cells.
Co-reporter:Xi Liu, Tao Liu, Chunhui Duan, Junyi Wang, Shuting Pang, Wentao Xiong, Yanming Sun, Fei Huang and Yong Cao
Journal of Materials Chemistry A 2017 - vol. 5(Issue 4) pp:NaN1723-1723
Publication Date(Web):2016/12/08
DOI:10.1039/C6TA08739F
Three perylenediimide (PDI) acceptors (P2O2, P2N2 and P4N4) were synthesized by functionalizing the bay positions of PDI with benzil, 2,3-diphenylquinoxaline and 2,3,7,8-tetraphenylpyrazino[2,3-g]quinoxaline as linkers, respectively. The photovoltaic properties of the three acceptor molecules have been investigated. The different PDI linker units show different physical and chemical properties of the PDIs. The three PDIs display different non-planar geometrical structures because of the different linker units, which affect the corresponding morphology of the blend films and also influence the charge mobility and fill factor (FF) of the organic solar cells (OSCs). Furthermore, the gradient energy levels of the three PDIs provide an efficient research model for the relationship of device open-circuit voltage (Voc) and energy levels. As the result, the P4N4 based non-fullerene devices show the best photovoltaic performance with a power conversion efficiency (PCE) of 5.71%, whereas the P2O2 and P2N2 based non-fullerene devices show relatively lower PCEs of 2.53% and 3.86%, respectively.
Co-reporter:Zhicheng Hu, Kai Zhang, Fei Huang and Yong Cao
Chemical Communications 2015 - vol. 51(Issue 26) pp:NaN5585-5585
Publication Date(Web):2015/01/15
DOI:10.1039/C4CC09433F
Water/alcohol soluble conjugated polymers (WSCPs), which can be processed from water/alcohol and other polar solvents, are suitable for the solution processing of multi-layer organic electronic devices. By using a thin layer WSCP as the cathode interfacial material, the resulting polymer light-emitting diodes (PLEDs) and polymer solar cells (PSCs) exhibited significant enhancements in their device performances. In this Feature Article, the authors aim to introduce a brief review of the recent developments and applications of WSCPs in highly efficient multi-layer solution processed PLEDs and PSCs.
Co-reporter:Chunhui Duan, Kai Zhang, Chengmei Zhong, Fei Huang and Yong Cao
Chemical Society Reviews 2013 - vol. 42(Issue 23) pp:NaN9104-9104
Publication Date(Web):2013/08/30
DOI:10.1039/C3CS60200A
Water/alcohol-soluble conjugated polymers (WSCPs) and small molecules (WSCSs) are materials that can be processed from water or other polar solvents. They provide good opportunities to fabricate multilayer organic optoelectronic devices without interface mixing by solution processing, and exhibit a promising interface modification ability for metal or metal oxide electrodes to greatly enhance the device performance of solar cells. Moreover, owing to their intriguing processability, WSCPs and WSCSs have great potential for applying environmentally friendly processing technologies to fabricate solar cells. In this review, the authors give an overview of recent developments in WSCPs and WSCSs, including their molecular design, material synthesis, functional principles and application as interface modification layers and photoactive components in emerging photovoltaic technologies such as organic/polymer solar cells, organic–inorganic hybrid solar cells and dye-sensitised solar cells.
Co-reporter:Wenzhan Xu, Yongtao Liu, Xiaojuan Huang, Lili Jiang, Qingduan Li, Xiaowen Hu, Fei Huang, Xiong Gong and Yong Cao
Journal of Materials Chemistry A 2016 - vol. 4(Issue 10) pp:NaN1958-1958
Publication Date(Web):2016/02/05
DOI:10.1039/C6TC00109B
In this study, we report solution-processed vanadium oxide (s-VOx) as the hole extraction layer (HEL) for polymer solar cells (PSCs). A s-VOx thin film is prepared simply by the spin-coating of ammonium metavanadate ammonal water solution on the surface of indium tin oxide (ITO) coated glass substrates, followed by thermal annealing at 210 °C for 5 minutes in air. The scanning Kelvin probe measurement indicates that the work function of the s-VOx HEL is −5.3 eV, which allows most of the conjugated polymers to form an Ohmic contact with the s-VOx HEL, resulting in a large open-circuit voltage for PSCs. It is found that PSCs incorporated with the s-VOx HEL possess a comparable power conversion efficiency and better shelf-stability with those incorporated with the poly (3,4-ethylenedioxythiophene):poly-(styrenesulfonate) anode buffer layer. Thus, our method provides a simple approach to prepare a solution-processed s-VOx HEL for higher performance PSCs.
Co-reporter:Jing Yue, Sheng Sun, Junfei Liang, Wenkai Zhong, Linfeng Lan, Lei Ying, Fei Huang, Wei Yang and Yong Cao
Journal of Materials Chemistry A 2016 - vol. 4(Issue 13) pp:NaN2479-2479
Publication Date(Web):2016/02/15
DOI:10.1039/C6TC00051G
Two novel regio-isomeric π-conjugated polymers consisting of the pyridyl unit flanked by diketopyrrolopyrrole as the electron-accepting unit and 2,5-bis(3-hexylthiophen-2-yl)thieno[3,2-b]thiophene as the electron-donating unit were designed and synthesized. The comparison of the optical and electrochemical properties indicated that the copolymer based on the nitrogen atom proximal to the central diketopyrrolopyrrole unit (p-PDBPy) exhibited bathochromic shifted absorption spectra and narrower bandgaps than the counterpart copolymer (d-PDBPy) with the distally oriented nitrogen atom, which can be correlated with the stronger intermolecular aggregation of the former as a result of the different intrinsic molecular geometry of the polymer backbone. Of particular interest is that the copolymer p-PDBPy exhibited a moderate hole mobility of 0.35 cm2 V−1 s−1, which is about three orders of magnitude higher than the hole mobility of 3.2 × 10−4 cm2 V−1 s−1 obtained based on the counterpart copolymer d-PDBPy, as measured using organic field-effect transistors. These results demonstrated that the delicate control of the pyridyl orientations along the polymer backbone is of vital importance for the molecular design of π-conjugated polymers for high-performance organic electronic devices.
Co-reporter:Wenkai Zhong, Jingyang Xiao, Sheng Sun, Xiao-Fang Jiang, Linfeng Lan, Lei Ying, Wei Yang, Hin-Lap Yip, Fei Huang and Yong Cao
Journal of Materials Chemistry A 2016 - vol. 4(Issue 21) pp:NaN4727-4727
Publication Date(Web):2016/04/11
DOI:10.1039/C6TC00271D
Two wide bandgap donor–acceptor type π-conjugated polymers based on dithienobenzodithiophene as the donor unit and difluorobenzotriazole or difluorobenzothiadiazole as the acceptor unit were designed and synthesized. The copolymer based on difluorobenzothiadiazole exhibited more pronounced aggregations in chlorobenzene solutions than that of the copolymer based on difluorobenzotriazole. Both copolymers exhibited relatively wide bandgaps with deep highest occupied molecular orbitals, leading to high open circuit voltages of over 0.95 V for the fabricated polymer solar cells. These copolymers exhibited quite analogous hole mobility of about 0.1 cm2 V−1 s−1 as measured by organic field effect transistors. Bulk heterojunction polymer solar cells based on these copolymers as the electron-donating materials and PC71BM as the electron-accepting material exhibited relatively high performance, with the best power conversion efficiency of 7.45% attained for the copolymer based on the difluorobenzothiadiazole unit. These results demonstrated that the constructed wide bandgap π-conjugated polymers can be promising candidates for the fabrication of high performance solar cells with multi-junction architectures.
Co-reporter:Chunhui Duan, Fei Huang and Yong Cao
Journal of Materials Chemistry A 2012 - vol. 22(Issue 21) pp:NaN10434-10434
Publication Date(Web):2012/03/09
DOI:10.1039/C2JM30470H
Bulk-heterojunction polymer solar cells have emerged as an attractive type of cost-effective solar energy–electrical power transforming device. Recently, great progress in the development of new photo-harvesting materials and device optimizations have been achieved in this field, resulting in the significant improvement of the power conversion efficiencies of polymer solar cells from around 1% to higher than 8.0%. The rational design and fine tailoring of the molecular structures of donor polymers significantly contributed to these prominent advances. Among all kinds of donor polymers, push–pull conjugated polymers, which consist of alternating electron-rich and electron-deficient units have been most extensively developed and have dominated the library of donor materials for polymer solar cells, because their intrinsic optical and electronic properties can be readily tuned to the desired situation by controlling the intramolecular charge transfer from donor unit to acceptor unit. This review provides a brief overview of the recent development of push–pull conjugated polymers and their application in solar cells. The relationships between the materials' chemical structures and properties, such as absorption spectra, energy levels, mobilities and photovoltaic behaviors, were also discussed.
Co-reporter:Charlie C. D. Wang, Wallace C. H. Choy, Chunhui Duan, Dixon D. S. Fung, Wei E. I. Sha, Feng-Xian Xie, Fei Huang and Yong Cao
Journal of Materials Chemistry A 2012 - vol. 22(Issue 3) pp:NaN1211-1211
Publication Date(Web):2011/11/18
DOI:10.1039/C1JM14150C
The effects of Au nanoparticles (NPs) incorporated into the active layer of polymer solar cells (PSCs) with a newly synthesized donor polymer are investigated in detail. Our work shows that localized surface plasmon resonance (LSPR) introduced by the metallic NPs can experimentally and theoretically enhance the light absorption in the active layer of PSCs because the strong LSPR near field mainly distributes laterally along the active layer. The understanding can be applied to other metallic NP incorporated organic solar cells. Meanwhile, our results show that electrical properties can counter-diminish the optical enhancement from LSPR and thus reduce the overall performance improvement. It is important that both optical and electrical properties need to be studied and optimized simultaneously for achieving improved power conversion efficiency. The study contributes to better understanding the uses of Au NPs for enhancing PSC performances.
![Pyrrolo[3,4-c]pyrrole-1,4-dione, 3,6-bis(5-bromo-2-thienyl)-2,5-dihydro-2,5-bis(2-octyldodecyl)-](/data/chemimg/139000/1260685-63-9.png)
![Pyrrolo[3,4-c]pyrrole-1,4-dione, 3,6-bis(5-bromo-2-thienyl)-2,5-dihydro-2,5-bis(2-octyldodecyl)-](/data/chemimg/139000/1260685-63-9_b.png)
![Anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone, 2,9-bis[3-(dimethylamino)propyl]-](/data/chemimg/134800/117901-97-0.png)
![Anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10(2H,9H)-tetrone, 2,9-bis[3-(dimethylamino)propyl]-](/data/chemimg/134800/117901-97-0_b.png)
![21H,23H-Porphine, 5,15-dibromo-10,20-bis[(2-butyloctyl)thienyl]-](/data/chemimg/3724000/1907692-65-2.png)
![21H,23H-Porphine, 5,15-dibromo-10,20-bis[(2-butyloctyl)thienyl]-](/data/chemimg/3724000/1907692-65-2_b.png)
![21H,23H-Porphine, 5,15-bis[(2-butyloctyl)thienyl]-](/data/chemimg/3724000/1907692-64-1.png)
![21H,23H-Porphine, 5,15-bis[(2-butyloctyl)thienyl]-](/data/chemimg/3724000/1907692-64-1_b.png)
![21H,23H-Porphine, 5,15-dibromo-10,20-bis[(2-hexyldecyl)thienyl]-](/data/chemimg/3723900/1879092-35-9.png)
![21H,23H-Porphine, 5,15-dibromo-10,20-bis[(2-hexyldecyl)thienyl]-](/data/chemimg/3723900/1879092-35-9_b.png)
![Benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone, 4,9-bis(5-bromo-2-thienyl)-2,7-bis(2-ethylhexyl)-, polymer with 2,2'-(9,9-dioctyl-9H-fluorene-2,7-](/data/chemimg/3733600/1867155-33-6.png)
![Benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone, 4,9-bis(5-bromo-2-thienyl)-2,7-bis(2-ethylhexyl)-, polymer with 2,2'-(9,9-dioctyl-9H-fluorene-2,7-](/data/chemimg/3733600/1867155-33-6_b.png)
![21H,23H-Porphine, 5,15-bis[(2-hexyldecyl)thienyl]-](/data/chemimg/3723800/1821659-23-7.png)
![21H,23H-Porphine, 5,15-bis[(2-hexyldecyl)thienyl]-](/data/chemimg/3723800/1821659-23-7_b.png)
![Benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone, 4,9-bis(5-bromo-2-thienyl)-2,7-bis(2-ethylhexyl)-, polymer with N,N,N',N'-tetramethyl-2,7-](/data/chemimg/3733400/1800206-45-4.png)
![Benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone, 4,9-bis(5-bromo-2-thienyl)-2,7-bis(2-ethylhexyl)-, polymer with N,N,N',N'-tetramethyl-2,7-](/data/chemimg/3733400/1800206-45-4_b.png)
![Poly[[2,3,5,6-tetrahydro-2,5-bis(2-octyldodecyl)-3,6-dioxopyrrolo[3,4-c]pyrrole-1,4-diyl]-2,5-thiophenediyl[4,8-bis[1-(2-hexyldecyl)-1H-1,2,3-triazol-4-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]-2,5-thiophenediyl]](/data/chemimg/3722600/1793071-16-5.png)
![Poly[[2,3,5,6-tetrahydro-2,5-bis(2-octyldodecyl)-3,6-dioxopyrrolo[3,4-c]pyrrole-1,4-diyl]-2,5-thiophenediyl[4,8-bis[1-(2-hexyldecyl)-1H-1,2,3-triazol-4-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]-2,5-thiophenediyl]](/data/chemimg/3722600/1793071-16-5_b.png)
![Poly[[2,3,5,6-tetrahydro-2,5-bis(2-octyldodecyl)-3,6-dioxopyrrolo[3,4-c]pyrrole-1,4-diyl]-2,5-thiophenediyl[4,8-bis[1-(2-butyloctyl)-1H-1,2,3-triazol-4-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]-2,5-thiophenediyl]](/data/chemimg/3722600/1793071-14-3.png)
![Poly[[2,3,5,6-tetrahydro-2,5-bis(2-octyldodecyl)-3,6-dioxopyrrolo[3,4-c]pyrrole-1,4-diyl]-2,5-thiophenediyl[4,8-bis[1-(2-butyloctyl)-1H-1,2,3-triazol-4-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]-2,5-thiophenediyl]](/data/chemimg/3722600/1793071-14-3_b.png)
![1H-1,2,3-Triazole, 4,4'-(2,6-dibromobenzo[1,2-b:4,5-b']dithiophene-4,8-diyl)bis[1-(2-octyldodecyl)-](/data/chemimg/3722600/1793071-05-2.png)
![1H-1,2,3-Triazole, 4,4'-(2,6-dibromobenzo[1,2-b:4,5-b']dithiophene-4,8-diyl)bis[1-(2-octyldodecyl)-](/data/chemimg/3722600/1793071-05-2_b.png)
![1H-1,2,3-Triazole, 4,4'-(2,6-dibromobenzo[1,2-b:4,5-b']dithiophene-4,8-diyl)bis[1-(2-hexyldecyl)-](/data/chemimg/3722600/1793071-04-1.png)
![1H-1,2,3-Triazole, 4,4'-(2,6-dibromobenzo[1,2-b:4,5-b']dithiophene-4,8-diyl)bis[1-(2-hexyldecyl)-](/data/chemimg/3722600/1793071-04-1_b.png)
![1H-1,2,3-Triazole, 4,4'-(2,6-dibromobenzo[1,2-b:4,5-b']dithiophene-4,8-diyl)bis[1-(2-butyloctyl)-](/data/chemimg/3722600/1793071-03-0.png)
![1H-1,2,3-Triazole, 4,4'-(2,6-dibromobenzo[1,2-b:4,5-b']dithiophene-4,8-diyl)bis[1-(2-butyloctyl)-](/data/chemimg/3722600/1793071-03-0_b.png)
![Poly[[4,4',5,5'-tetrahydro-4,4'-bis(2-octyldodecyl)-5,5'-dioxo[7,7'-bidithieno[3,2-b:2',3'-d]pyridine]-2,2'-diyl]-2,5-thiophenediyl]](/data/chemimg/3731500/1696391-85-1.png)
![Poly[[4,4',5,5'-tetrahydro-4,4'-bis(2-octyldodecyl)-5,5'-dioxo[7,7'-bidithieno[3,2-b:2',3'-d]pyridine]-2,2'-diyl]-2,5-thiophenediyl]](/data/chemimg/3731500/1696391-85-1_b.png)
![Borane, 1,1',1'',1'''-[1,2-ethenediylidenetetrakis([1,1'-biphenyl]-4',4-diyl)]tetrakis[1,1-bis(2,4,6-trimethylphenyl)-](/data/chemimg/3785000/1628446-26-3.png)
![Borane, 1,1',1'',1'''-[1,2-ethenediylidenetetrakis([1,1'-biphenyl]-4',4-diyl)]tetrakis[1,1-bis(2,4,6-trimethylphenyl)-](/data/chemimg/3785000/1628446-26-3_b.png)
![[1,1'-Biphenyl]-4-amine, 4'-[1-[4'-[bis(2,4,6-trimethylphenyl)boryl][1,1'-biphenyl]-4-yl]-2,2-bis(4-bromophenyl)ethenyl]-N,N-diphenyl-](/data/chemimg/3784200/1628446-25-2.png)
![[1,1'-Biphenyl]-4-amine, 4'-[1-[4'-[bis(2,4,6-trimethylphenyl)boryl][1,1'-biphenyl]-4-yl]-2,2-bis(4-bromophenyl)ethenyl]-N,N-diphenyl-](/data/chemimg/3784200/1628446-25-2_b.png)
![[1,1'-Biphenyl]-4-amine, N,N-diphenyl-4'-[1,2,2-tris[4'-[bis(2,4,6-trimethylphenyl)boryl][1,1'-biphenyl]-4-yl]ethenyl]-](/data/chemimg/3784200/1628446-19-4.png)
![[1,1'-Biphenyl]-4-amine, N,N-diphenyl-4'-[1,2,2-tris[4'-[bis(2,4,6-trimethylphenyl)boryl][1,1'-biphenyl]-4-yl]ethenyl]-](/data/chemimg/3784200/1628446-19-4_b.png)
![[1,1'-Biphenyl]-4-amine, 4',4'''-[2,2-bis[4'-[bis(2,4,6-trimethylphenyl)boryl][1,1'-biphenyl]-4-yl]ethenylidene]bis[N,N-diphenyl-](/data/chemimg/3784200/1628446-12-7.png)
![[1,1'-Biphenyl]-4-amine, 4',4'''-[2,2-bis[4'-[bis(2,4,6-trimethylphenyl)boryl][1,1'-biphenyl]-4-yl]ethenylidene]bis[N,N-diphenyl-](/data/chemimg/3784200/1628446-12-7_b.png)
![3'H-Cyclopropa[1,9][5,6]fullerene-C60-Ih-3'-butanoic acid, 3'-phenyl-, 2-[[2-(dimethylamino)ethyl]methylamino]ethyl ester](/data/chemimg/3719300/1478675-82-9.png)
![3'H-Cyclopropa[1,9][5,6]fullerene-C60-Ih-3'-butanoic acid, 3'-phenyl-, 2-[[2-(dimethylamino)ethyl]methylamino]ethyl ester](/data/chemimg/3719300/1478675-82-9_b.png)
![Pyrrolo[3,4-c]pyrrole-1,4-dione, 3,6-bis(5-bromo-2-pyridinyl)-2,5-dihydro-2,5-bis(2-octyldodecyl)-](/data/chemimg/3730500/1455028-34-8.png)
![Pyrrolo[3,4-c]pyrrole-1,4-dione, 3,6-bis(5-bromo-2-pyridinyl)-2,5-dihydro-2,5-bis(2-octyldodecyl)-](/data/chemimg/3730500/1455028-34-8_b.png)
![Dithieno[2,3-d:2',3'-d']benzo[1,2-b:4,5-b']dithiophene-5,10-dione](/data/chemimg/2265700/1446476-79-4.png)
![Dithieno[2,3-d:2',3'-d']benzo[1,2-b:4,5-b']dithiophene-5,10-dione](/data/chemimg/2265700/1446476-79-4_b.png)
![Benzo[1,2-b:4,5-b']dithiophene, 4,8-bis[5-(2-hexyldecyl)-2-thienyl]-](/data/chemimg/139800/1422748-36-4.png)
![Benzo[1,2-b:4,5-b']dithiophene, 4,8-bis[5-(2-hexyldecyl)-2-thienyl]-](/data/chemimg/139800/1422748-36-4_b.png)
![Stannane, 1,1'-[4,8-bis[5-(2-butyloctyl)-2-thienyl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]bis[1,1,1-trimethyl-](/data/chemimg/3778100/1402460-13-2.png)
![Stannane, 1,1'-[4,8-bis[5-(2-butyloctyl)-2-thienyl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]bis[1,1,1-trimethyl-](/data/chemimg/3778100/1402460-13-2_b.png)
![Benzo[1,2-b:4,5-b']dithiophene, 4,8-bis[5-(2-ethylhexyl)-2-thienyl]-](/data/chemimg/139500/1352642-35-3.png)
![Benzo[1,2-b:4,5-b']dithiophene, 4,8-bis[5-(2-ethylhexyl)-2-thienyl]-](/data/chemimg/139500/1352642-35-3_b.png)
![Benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone, 4,9-bis(5-bromo-2-thienyl)-2,7-bis(2-ethylhexyl)-](/data/chemimg/3730500/1320282-67-4.png)
![Benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone, 4,9-bis(5-bromo-2-thienyl)-2,7-bis(2-ethylhexyl)-](/data/chemimg/3730500/1320282-67-4_b.png)
![Benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone, 2,7-bis(2-ethylhexyl)-4,9-di-2-thienyl-](/data/chemimg/3730500/1320282-65-2.png)
![Benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone, 2,7-bis(2-ethylhexyl)-4,9-di-2-thienyl-](/data/chemimg/3730500/1320282-65-2_b.png)
![Stannane, 1,1'-[4,8-bis[(2-butyloctyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]bis[1,1,1-trimethyl-](/data/chemimg/154400/1271439-08-7.png)
![Stannane, 1,1'-[4,8-bis[(2-butyloctyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]bis[1,1,1-trimethyl-](/data/chemimg/154400/1271439-08-7_b.png)
![Stannane, 1,1'-[4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]bis[1,1,1-trimethyl-](/data/chemimg/154400/1254985-74-4.png)
![Stannane, 1,1'-[4,8-bis[(2-hexyldecyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]bis[1,1,1-trimethyl-](/data/chemimg/154400/1254985-74-4_b.png)
![Thieno[3,4-b]thiophene-2-carboxylic acid, 4,6-dibromo-3-fluoro-, 2-ethylhexyl ester](/data/chemimg/1642600/1237479-38-7.png)
![Thieno[3,4-b]thiophene-2-carboxylic acid, 4,6-dibromo-3-fluoro-, 2-ethylhexyl ester](/data/chemimg/1642600/1237479-38-7_b.png)
![Thieno[3,4-b]thiophene-2-carboxylic acid, 4,6-dibromo-, 2-ethylhexyl ester](/data/chemimg/189600/1160823-81-3.png)
![Thieno[3,4-b]thiophene-2-carboxylic acid, 4,6-dibromo-, 2-ethylhexyl ester](/data/chemimg/189600/1160823-81-3_b.png)
![Benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone, 4,9-dibromo-2,7-bis(2-ethylhexyl)-](/data/chemimg/148200/1088205-02-0.png)
![Benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetrone, 4,9-dibromo-2,7-bis(2-ethylhexyl)-](/data/chemimg/148200/1088205-02-0_b.png)
![Di-tert-butyl 3,6-bis(5-bromothiophen-2-yl)-1,4-dioxopyrrolo[3,4-c] pyrrole-2,5(1H,4H)-dicarboxylate](http://img.cochemist.com/ccimg/1046900/1046864-84-9.png)
![Di-tert-butyl 3,6-bis(5-bromothiophen-2-yl)-1,4-dioxopyrrolo[3,4-c] pyrrole-2,5(1H,4H)-dicarboxylate](http://img.cochemist.com/ccimg/1046900/1046864-84-9_b.png)
![Di-tert-butyl 1,4-dioxo-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-2,5(1h,4h)-dicarboxylate](http://img.cochemist.com/ccimg/1046900/1046864-83-8.png)
![Di-tert-butyl 1,4-dioxo-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-2,5(1h,4h)-dicarboxylate](http://img.cochemist.com/ccimg/1046900/1046864-83-8_b.png)
![2,7-Dibromo-9,9-bis[4-(2'-ethylhexyloxy)phenyl]-fluorene](/data/chemimg/1040734-87-9.png)
![2,7-Dibromo-9,9-bis[4-(2'-ethylhexyloxy)phenyl]-fluorene](/data/chemimg/1040734-87-9_b.png)
![(4,4-Bis(2-ethylhexyl)-4H-cyclopenta[1,2-b:5,4-b']dithiophene-2,6-diyl)bis(trimethylstannane)](http://img.cochemist.com/ccimg/920600/920504-00-3.png)
![(4,4-Bis(2-ethylhexyl)-4H-cyclopenta[1,2-b:5,4-b']dithiophene-2,6-diyl)bis(trimethylstannane)](http://img.cochemist.com/ccimg/920600/920504-00-3_b.png)
![POLY[(9,9-DIHEXYL-9H-FLUORENE-2,7-DIYL)-1,4-PHENYLENEOXY-1,4-PHENYLENE]](http://img.cochemist.com/ccimg/914700/914641-86-4.png)
![POLY[(9,9-DIHEXYL-9H-FLUORENE-2,7-DIYL)-1,4-PHENYLENEOXY-1,4-PHENYLENE]](http://img.cochemist.com/ccimg/914700/914641-86-4_b.png)
![METHANONE, (4-BROMOPHENYL)[4'-(DIPHENYLAMINO)[1,1'-BIPHENYL]-4-YL]-](http://img.cochemist.com/ccimg/817700/817624-97-8.png)
![METHANONE, (4-BROMOPHENYL)[4'-(DIPHENYLAMINO)[1,1'-BIPHENYL]-4-YL]-](http://img.cochemist.com/ccimg/817700/817624-97-8_b.png)
![2,5-Bis(trimethylstannyl)thieno[3,2-b]thiophene](http://img.cochemist.com/ccimg/470000/469912-82-1.png)
![2,5-Bis(trimethylstannyl)thieno[3,2-b]thiophene](http://img.cochemist.com/ccimg/470000/469912-82-1_b.png)
![METHANONE, BIS[4-(DECYLOXY)PHENYL]-](http://img.cochemist.com/ccimg/402000/401916-98-1.png)
![METHANONE, BIS[4-(DECYLOXY)PHENYL]-](http://img.cochemist.com/ccimg/402000/401916-98-1_b.png)
![Poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,7-diyl)]](/data/chemimg/107700/210347-52-7.png)
![Poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(benzo[2,1,3]thiadiazol-4,7-diyl)]](/data/chemimg/107700/210347-52-7_b.png)
![[2]Benzopyrano[6,5,4-def][2]benzopyran-1,3,6,8-tetrone, 4,9-dibromo-](/data/chemimg/1015800/83204-68-6.png)
![[2]Benzopyrano[6,5,4-def][2]benzopyran-1,3,6,8-tetrone, 4,9-dibromo-](/data/chemimg/1015800/83204-68-6_b.png)
![[1,1'-Biphenyl]-2,2'-dicarboxylicacid, 4,4',6,6'-tetranitro-](http://img.cochemist.com/ccimg/18900/18811-76-2.png)
![[1,1'-Biphenyl]-2,2'-dicarboxylicacid, 4,4',6,6'-tetranitro-](http://img.cochemist.com/ccimg/18900/18811-76-2_b.png)
![Methanone, [4-(diphenylamino)phenyl]phenyl-](http://img.cochemist.com/ccimg/17000/16911-33-4.png)
![Methanone, [4-(diphenylamino)phenyl]phenyl-](http://img.cochemist.com/ccimg/17000/16911-33-4_b.png)
![Benzene,1,1'-[(dimethylsilylene)di-2,1-ethynediyl]bis-](http://img.cochemist.com/ccimg/2200/2170-08-3.png)
![Benzene,1,1'-[(dimethylsilylene)di-2,1-ethynediyl]bis-](http://img.cochemist.com/ccimg/2200/2170-08-3_b.png)
![21H,23H-Porphine, 5,15-dibromo-10,20-bis[5-(2-ethylhexyl)-2-thienyl]-](/data/chemimg/3723900/1796597-88-0.png)
![21H,23H-Porphine, 5,15-dibromo-10,20-bis[5-(2-ethylhexyl)-2-thienyl]-](/data/chemimg/3723900/1796597-88-0_b.png)
![21H,23H-Porphine, 5,15-bis[5-(2-ethylhexyl)-2-thienyl]-](/data/chemimg/3723900/1796597-87-9.png)
![21H,23H-Porphine, 5,15-bis[5-(2-ethylhexyl)-2-thienyl]-](/data/chemimg/3723900/1796597-87-9_b.png)
![Stannane, 1,1'-[4,8-bis[5-(2-ethylhexyl)-2-thienyl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]bis[1,1,1-trimethyl-](/data/chemimg/139400/1352642-37-5.png)
![Stannane, 1,1'-[4,8-bis[5-(2-ethylhexyl)-2-thienyl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]bis[1,1,1-trimethyl-](/data/chemimg/139400/1352642-37-5_b.png)
![Pyrrolo[3,4-c]pyrrole-1,4-dione, 3-(5-bromo-2-thienyl)-2,5-bis(2-ethylhexyl)-2,5-dihydro-6-(2-thienyl)-](/data/chemimg/139400/1308671-90-0.png)
![Pyrrolo[3,4-c]pyrrole-1,4-dione, 3-(5-bromo-2-thienyl)-2,5-bis(2-ethylhexyl)-2,5-dihydro-6-(2-thienyl)-](/data/chemimg/139400/1308671-90-0_b.png)
![4,4-di-n-octyl-2,6-bis(trimethylstannyl)dithieno[3,2-b:2',3'-d]silole](http://img.cochemist.com/ccimg/1160200/1160106-15-9.png)
![4,4-di-n-octyl-2,6-bis(trimethylstannyl)dithieno[3,2-b:2',3'-d]silole](http://img.cochemist.com/ccimg/1160200/1160106-15-9_b.png)
![Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]](http://img.cochemist.com/ccimg/138200/138184-36-8.png)
![Poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]](http://img.cochemist.com/ccimg/138200/138184-36-8_b.png)
![Naphtho[1,2-c:5,6-c']bis[1,2,5]thiadiazole](http://img.cochemist.com/ccimg/133600/133546-47-1.png)
![Naphtho[1,2-c:5,6-c']bis[1,2,5]thiadiazole](http://img.cochemist.com/ccimg/133600/133546-47-1_b.png)
![3,7-dibromodibenzo[b,d]thiophene 5,5-dioxide](http://img.cochemist.com/ccimg/83900/83834-12-2.png)
![3,7-dibromodibenzo[b,d]thiophene 5,5-dioxide](http://img.cochemist.com/ccimg/83900/83834-12-2_b.png)
![Stannane, 1,1'-[4,8-bis(4,5-didecyl-2-thienyl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]bis[1,1,1-trimethyl-](/data/chemimg/3781900/1307899-54-2.png)
![Stannane, 1,1'-[4,8-bis(4,5-didecyl-2-thienyl)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl]bis[1,1,1-trimethyl-](/data/chemimg/3781900/1307899-54-2_b.png)
![BORONIC ACID, [4-[BIS(2,4,6-TRIMETHYLPHENYL)BORYL]PHENYL]-](http://img.cochemist.com/ccimg/684300/684243-16-1.png)
![BORONIC ACID, [4-[BIS(2,4,6-TRIMETHYLPHENYL)BORYL]PHENYL]-](http://img.cochemist.com/ccimg/684300/684243-16-1_b.png)
