Co-reporter:Yunlong Ma, Meiqi Zhang, Yu Yan, Jingming Xin, Tao Wang, Wei Ma, Changquan Tang, and Qingdong Zheng
Chemistry of Materials September 26, 2017 Volume 29(Issue 18) pp:7942-7942
Publication Date(Web):August 25, 2017
DOI:10.1021/acs.chemmater.7b02887
Two novel small molecule acceptors (DTNIC6 and DTNIC8) based on a ladder-type dithienonaphthalene (DTN) building block with linear (hexyl) or branched (2-ethylhexyl) alkyl substituents are designed and synthesized. Both acceptors exhibit strong and broad absorption in the range from 500 to 720 nm as well as appropriate highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels. Replacing the linear hexyl chains with the branched 2-ethylhexyl chains has a large impact on the film morphology of photoactive layers. In the blend film based on DTNIC8 bearing the branched alkyl chains, morphology with well-defined phase separation was observed. This optimal phase morphology yields efficient exciton dissociation, reduced bimolecular recombination, and enhanced and balanced charge carrier mobilities. Benefited from these factors, organic solar cells (OSCs) based on PBDB-T:DTNIC8 deliver a highest power conversion efficiency (PCE) of 9.03% with a high fill factor (FF) of 72.84%. This unprecedented high FF of 72.84% is one of the highest FF values reported for nonfullerene OSCs. Our work not only affords a promising electron acceptor for nonfullerene solar cells but also provides a side-chain engineering strategy toward high performance OSCs.
Co-reporter:Zhi-Gang Gu;Shan-Ci Chen;Wen-Qiang Fu;Jian Zhang
ACS Applied Materials & Interfaces March 1, 2017 Volume 9(Issue 8) pp:7259-7264
Publication Date(Web):February 9, 2017
DOI:10.1021/acsami.6b14541
Metal–organic framework (MOF) thin films are important in the application of sensors and devices. However, the application of MOF thin films in organic field effect transistors (OFETs) is still a challenge to date. Here, we first use the MOF thin film prepared by a liquid-phase epitaxial (LPE) approach (also called SURMOFs) to modify the SiO2 dielectric layer in the OFETs. After the semiconductive polymer of PTB7-Th (poly[4,8-bis(5-(2-ethylhexyl)thiophene-2-yl)benzo[1,2-b:4,5-b′]dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]) was coated on MOF/SiO2 and two electrodes on the semiconducting film were deposited sequentially, MOF-based OFETs were fabricated successfully. By controlling the LPE cycles of SURMOF HKUST-1 (also named Cu3(BTC)2, BTC = 1,3,5-benzenetricarboxylate), the performance of the HKUST-1/SiO2-based OFETs showed high charge mobility and low threshold voltage. This first report on the application of MOF thin film in OFETs will offer an effective approach for designing a new kind of materials for the OFET application.Keywords: dielectric layer; epitaxial growth; metal−organic frameworks; organic field-effect transistor; thin film;
Co-reporter:Jiajun WeiZhigang Yin, Shan-Ci Chen, Qingdong Zheng
ACS Applied Materials & Interfaces February 22, 2017 Volume 9(Issue 7) pp:
Publication Date(Web):January 24, 2017
DOI:10.1021/acsami.6b13724
In this study, Sn-doped ZnO (ZTO) is prepared by a sol–gel method and is employed as an electron transport material for organic solar cells (OSCs). After Sn modification, the fabricated ZTO films exhibited better charge transport properties and smoother surface morphology, especially for those processed at a low temperature of 120 °C. By incorporation of the high-temperature (200 °C) processed ZTO films, inverted OSCs showed the highest power conversion efficiency (PCE) of 9.32%, which is higher than those based on the same temperature processed ZnO films. For the devices based on the low-temperature processed ZTO, a high PCE over 9.0% with long-term stability was achieved, which is much better than those based on the same temperature processed ZnO (8.46% PCE). Here, the ZTO films can be fabricated without high-temperature annealing, demonstrating their great potential as electron transport layers for efficient flexible OSCs.Keywords: efficiency; electron transport; interface engineering; organic solar cells; solution-processed;
Co-reporter:Meng Wang;Dongdong Cai;Jingming Xin;Wei Ma;Qisheng Tu
Journal of Materials Chemistry A 2017 vol. 5(Issue 24) pp:12015-12021
Publication Date(Web):2017/06/20
DOI:10.1039/C7TA03316H
Ternary conjugated D–A copolymers are designed and synthesized by using indenothiophene and benzodithiophene as the weak and the strong donors, respectively, and fluorinated benzodithiazole as the strong acceptor. The best performance copolymer delivers a high PCE of 9.08%, which is a record efficiency for ternary conjugated D–A copolymers reported to date.
Co-reporter:Zhigang Yin;Jiajun Wei;Shan-Ci Chen;Dongdong Cai;Yunlong Ma;Meng Wang
Journal of Materials Chemistry A 2017 vol. 5(Issue 8) pp:3888-3899
Publication Date(Web):2017/02/21
DOI:10.1039/C6TA10981K
Semitransparent organic solar cells (STOSCs) have shown great promise as advanced window integrated photovoltaics for architectural and automotive utilization. In the applications, STOSCs should possess both long-term stability and high power conversion efficiency (PCE). Here, long lifetime stable and efficient STOSCs with good transparency color perception are demonstrated by combining a transparent ZnMgO-modified cathode with thin MoO3/Ag anodes. The resulting devices exhibit high PCEs (6.83–8.15%) with tunable average visible transmittances (21.6–3.8%) and good color perception close to white light. The combination of the ZnMgO-modified cathode with the MoO3/Ag anode in the STOSCs leads to long-term device shelf lifetime due to their barrier effects for oxygen and water. The STOSCs can maintain over 90% of their original PCEs over two-month storage under ambient conditions. More importantly, record high PCEs of 7.08% and 7.02% were retained for the STOSCs after storage for 1 year and 2 years, respectively, demonstrating the long lifetime stability for high-efficiency STOSCs. These findings offer a promising path to develop STOSCs with high efficiencies, long lifetime and good color perception towards practical applications.
Co-reporter:Changquan Tang 汤昌泉;Shan-Ci Chen 陈善慈;Qi Shang 尚启
Science China Materials 2017 Volume 60( Issue 8) pp:707-716
Publication Date(Web):17 July 2017
DOI:10.1007/s40843-017-9059-3
Three new asymmetric acceptor-donor-acceptor structured molecules are designed and synthesized by incorporating indenothiophene as the central core. Their bandgaps and energy levels can be easily tuned by varying the electron withdrawing ability of the terminal groups such as dicyanovinyl, 3-ethylrhodanine, and 2-(1,1-dicyanomethylene)-3-ethyl-rhodanine. Inverted polymer solar cells using these molecules as acceptors and PTB7-Th as a donor material afford a highest power conversion efficiency of 7.49% with a high open circuit voltage of 1.02 V as well as a low energy loss of 0.59 eV.本文设计合成了三个新型含茚并噻吩的“受体-给体-受体”型不对称非富勒烯受体材料. 通过使用具有不同吸电子能力的末端基团(如:二氰乙烯基、3-乙基绕丹宁、2-二氰亚甲基-3-乙基绕丹宁)实现了目标材料的带隙和能级调控. 以这些非富勒烯受体材料与PTB7-Th给体材料共混制备的倒置聚合物太阳电池, 实现了高达7.49%的光电转换效率和1.02伏的高开路电压以及0.59电子伏的低能量损失.
Co-reporter:Shan-Ci Chen, Qingdong Zheng, Zhigang Yin, Dongdong Cai, Yunlong Ma
Organic Electronics 2017 Volume 47(Volume 47) pp:
Publication Date(Web):1 August 2017
DOI:10.1016/j.orgel.2017.05.008
•High performance thermal-treatment-free tandem polymer solar cells are fabricated.•PFN processed at ambient temperatures was used as buffer layers for both subcells.•A highest PCE of 10.79% was achieved.•Tandem cells exhibit higher fill factors compared to the corresponding single cells.It is an effective way to enhance device performance of polymer solar cells (PSCs) by using a tandem structure that combines two or more solar cells. For tandem PSCs, the buffer layer plays an important role in determining the device performance. The most commonly used buffer layers, such as PEDOT:PSS, TiOx, and ZnO, need thermal treatments that are not beneficial for reducing the fabrication complexity and cost of tandem PSCs. It is necessary to develop tandem PSCs fabricated by a thermal-treatment-free process. In this paper, we report high performance thermal-treatment-free tandem PSCs by developing PFN as buffer layers for both subcells. A power conversion efficiency (PCE) of 10.50% and a high fill factor of 72.44% were achieved by stacking two identical PTB7:PC71BM subcells. When adopting a rear PTB7-Th:PC71BM subcell, the highest PCE of 10.79% was further obtained for the tandem devices. The thermal-treatment-free process is especially applicable to flexible devices, in which plastic substrates are usually used.Download high-res image (237KB)Download full-size image
Co-reporter:Jiajun Wei, Qisheng Tu, Qingdong Zheng
Dyes and Pigments 2017 Volume 144(Volume 144) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.dyepig.2017.05.026
•A heteroheptacene-based small molecule was designed and synthesized.•Non-fullerene solar cells with an inverted device configuration were fabricated.•The best power conversion efficiency of 6.23% was achieved.•The incorporation of strong electron withdrawing groups resulted in an electron affinity decrease.The design, synthesis, characterization and photovoltaic properties of a small molecule (CDTCN) based on a heteroheptacene unit are presented. The incorporation of strong electron withdrawing 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile groups results in a decrease in the electron affinity of the heteroheptacene-based semiconductor and renders its decent electron transportation property. Organic solar cells using CDTCN as the acceptor material and a wide bandgap polymer (PBDB-T) as the donor material gave a high power conversion efficiency of 6.23% with a high open-circuit voltage of 0.96 V, a short-circuit current density of 11.26 mA cm−2 and a fill factor of 57.58%. The results demonstrate that the heteroheptacene is a promising electron donating core for constructing new non-fullerene acceptors with good performance.Download high-res image (161KB)Download full-size image
Co-reporter:Qi Shang;Meng Wang;Jiajun Wei
RSC Advances (2011-Present) 2017 vol. 7(Issue 29) pp:18144-18150
Publication Date(Web):2017/03/20
DOI:10.1039/C7RA01902E
The development of organic semiconductors is of key importance in order to improve the performance of organic solar cells (OSCs). Three indenothiophene (IT)-containing small molecules (IT3T, ITFBT and IT2FBT) were designed and synthesized for small molecule OSCs. The thermal, optical, and electrochemical properties of the molecules were investigated. The optical bandgaps of the three small molecules are ranged from 1.80 to 2.20 eV depending on different terminal groups flanked on the IT. We study the photovoltaic performances of the three molecules by fabricating OSCs with PC71BM as an electron acceptor. Among the three molecules, ITFBF exhibited the best power conversion efficiency of 4.57% with a high open circuit voltage (VOC) of 0.98 V. We also briefly discuss structure–property guidelines for small molecules used for OSCs. The results demonstrate that IT-based small molecules are promising for small molecule OSCs with large VOCs.
Co-reporter:Yunlong Ma;Zhenjing Kang
Journal of Materials Chemistry A 2017 vol. 5(Issue 5) pp:1860-1872
Publication Date(Web):2017/01/31
DOI:10.1039/C6TA09325F
As key components in the active layer of multi-junction, ternary blend, or non-fullerene polymer solar cells (PSCs), wide bandgap semiconducting polymers have the characteristic of exhibiting strong absorption bands in the short-wavelength region. In multi-junction, ternary blend, or non-fullerene PSCs, wide bandgap polymers can provide complementary absorption profiles with low bandgap counterparts, thereby further increasing power conversion efficiencies. In this review, we summarize the recent advances of wide bandgap semiconducting polymers and their applications in PSCs, and discuss the designs as well as the material structure–property-device performance correlations. Finally, we conclude by highlighting the challenges and future developments of wide bandgap semiconducting polymers.
Co-reporter:Meng Wang;Dongdong Cai;Zhigang Yin;Shan-Ci Chen;Cheng-Feng Du
Advanced Materials 2016 Volume 28( Issue 17) pp:3359-3365
Publication Date(Web):
DOI:10.1002/adma.201505957
Co-reporter:Zhigang Yin;Shan-Ci Chen;Dongdong Cai;Yunlong Ma
Advanced Energy Materials 2016 Volume 6( Issue 4) pp:
Publication Date(Web):
DOI:10.1002/aenm.201501493
Currently, one main challenge in organic solar cells (OSCs) is to achieve both good stability and high power conversion efficiencies (PCEs). Here, highly efficient and long-term stable inverted OSCs are fabricated by combining controllable ZnMgO (ZMO) cathode interfacial materials with a polymer:fullerene bulk-heterojunction. The resulting devices based on the nanocolloid/nanoridge ZMO electron-transporting layers (ETLs) show greatly enhanced performance compared to that of the conventional devices or control devices without ZMO or with ZnO ETLs. The ZMO-based OSCs maintain 84%–93% of their original PCEs over 1-year storage under ambient conditions. An initial PCE of 9.39% is achieved for the best device, and it still retains a high PCE of 8.06% after 1-year storage, which represents a record high value for long-term stable OSCs. The excellent performance is attributed to the enhanced electron transportation/collection, reduced interfacial energy losses, and improved stability of the nanocolloid ZMO ETL. These findings provide a promising way to develop OSCs with high efficiencies and long device lifetime towards practical applications.
Co-reporter:Qisheng Tu, Dongdong Cai, Lixin Wang, Jiajun Wei, Qi Shang, Shan-Ci Chen, Yunlong Ma, Zhigang Yin, Changquan Tang and Qingdong Zheng
Journal of Materials Chemistry A 2016 vol. 4(Issue 25) pp:6160-6168
Publication Date(Web):02 Jun 2016
DOI:10.1039/C6TC01778A
Five wide bandgap conjugated polymers based on diindenocarbazole (DIC) and dithienylbenzothiadiazole (DTBT) alternating units have been designed and prepared to investigate the effects of side chains on the photovoltaic performance of the polymers. All the polymers are soluble in common organic solvents and they show similar optical bandgaps of around 2.0 eV as well as deep-lying highest occupied molecular orbital (HOMO) energy levels (below −5.48 eV). Bulk heterojunction (BHJ) polymer solar cells (PSCs) using phenyl-C71-butyric acid methyl ester (PC71BM) as the electron acceptor material were fabricated. The side chains on the polymer backbone have a strong impact on the film morphology of the polymer:PC71BM blends. A phase separation with a relatively larger domain size was found for the polymers with longer side chains, while those with relatively shorter alkyl chains could form uniform films featuring a phase separation with a smaller domain size. Finally, PSCs based on PC1BT6:PC71BM exhibited an outstanding power conversion efficiency of 7.34% with a high open-circuit voltage (Voc) of 0.95 V. Our results demonstrate that the judicious design of side-chains is effective in improving the photovoltaic performance of DIC-based polymers. With a larger bandgap than P3HT but an improved power conversion efficiency (PCE) with a large Voc, this type of DIC-based polymer should be a promising bottom layer material for tandem solar cells.
Co-reporter:Zhigang Yin;Jiajun Wei
Advanced Science 2016 Volume 3( Issue 8) pp:
Publication Date(Web):
DOI:10.1002/advs.201500362
Organic solar cells (OSCs) have shown great promise as low-cost photovoltaic devices for solar energy conversion over the past decade. Interfacial engineering provides a powerful strategy to enhance efficiency and stability of OSCs. With the rapid advances of interface layer materials and active layer materials, power conversion efficiencies (PCEs) of both single-junction and tandem OSCs have exceeded a landmark value of 10%. This review summarizes the latest advances in interfacial layers for single-junction and tandem OSCs. Electron or hole transporting materials, including metal oxides, polymers/small-molecules, metals and metal salts/complexes, carbon-based materials, organic-inorganic hybrids/composites, and other emerging materials, are systemically presented as cathode and anode interface layers for high performance OSCs. Meanwhile, incorporating these electron-transporting and hole-transporting layer materials as building blocks, a variety of interconnecting layers for conventional or inverted tandem OSCs are comprehensively discussed, along with their functions to bridge the difference between adjacent subcells. By analyzing the structure–property relationships of various interfacial materials, the important design rules for such materials towards high efficiency and stable OSCs are highlighted. Finally, we present a brief summary as well as some perspectives to help researchers understand the current challenges and opportunities in this emerging area of research.
Co-reporter:Jiajun Wei, Zhigang Yin, Shan-Ci Chen, Dongdong Cai and Qingdong Zheng
RSC Advances 2016 vol. 6(Issue 45) pp:39137-39143
Publication Date(Web):14 Apr 2016
DOI:10.1039/C6RA01204C
Here we employed a simple solution-processed method to prepare MoSx films as hole-transport layers (HTLs) in polymer solar cells (PSCs). Impressive performance was achieved with a power conversion efficiency (PCE) of 7.50%, which is comparable to those of the conventional devices with PEDOT:PSS HTLs. The surface and optoelectronic characteristics of MoSx films obtained from different conditions were investigated. The results reveal that the annealing temperature of MoSx is one of the most important factors on determining the device performance. PSCs based on MoSx films exhibited much better device stability compared to the counterpart based on PEDOT:PSS, suggesting that the MoSx film is a promising alternative HTL for PSCs.
Co-reporter:Lixin Wang, Dongdong Cai, Changquan Tang, Meng Wang, Zhigang Yin and Qingdong Zheng
Journal of Materials Chemistry A 2015 vol. 3(Issue 22) pp:5631-5641
Publication Date(Web):02 Apr 2015
DOI:10.1039/C5TC00398A
We have developed a facile synthetic route to a ladder-type donor unit (SDCT) wherein two outer thiophene subunits are covalently fastened to the central dibenzothiophene core through two sp3-hybridized bridging carbons. An innovative transformation from an aryl ketone group to an aryl ester group was applied to construct the ladder-type molecular skeleton, and the overall synthetic yield toward the donor unit has been significantly improved by choosing aryl side chains instead of aliphatic ones to avoid competing dehydration reactions. To reveal the effects of π-spacers and heteroatom substituents, three donor–acceptor (D–A) copolymers containing SDCT and acceptor units of 2,1,3-benzothiadiazole (BT), 2,1,3-benzoxadiazole (BO), or 4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (DTBT) were synthesized, characterized and used for polymer solar cells (PSCs). All polymers exhibit blue-shifted absorption spectra and deeper-lying HOMO energy levels compared to the previous carbazole-based skeleton analogues. In comparison with its analogous polymer with the same π-conjugated backbone, the polymer with alkoxy-substituted BT as the acceptor unit (PSBT) shows an order of magnitude higher OFET mobility (1.8 × 10−4versus 1.25 × 10−5 cm2 V−1 s−1). An optimal device based on PSBT:PC71BM (1/3 in wt%) delivers a respectable PCE of 5.18% and a high Voc of 0.94 V, all of which are superior to those of the carbazole-based analogue (PCE = 3.7%, Voc = 0.80 V) and greatly surpass the values of a previously reported dibenzothiophene-based polymer (PCE = 0.76%, Voc = 0.64 V). These results demonstrate that SDCT is a promising building block for constructing photovoltaic polymers and the synthetic strategy developed herein can be used to prepare other dibenzothiophene-cored ladder-type heptacyclic units.
Co-reporter:Meng Wang, Hao Qin, Lixin Wang, Jiajun Wei, Dongdong Cai, Zhigang Yin, Yunlong Ma, Shan-Ci Chen, Changquan Tang and Qingdong Zheng
Journal of Materials Chemistry A 2015 vol. 3(Issue 43) pp:21672-21681
Publication Date(Web):14 Sep 2015
DOI:10.1039/C5TA04872A
Side-chain engineering of polymer backbones can induce subtle variations in polymer properties, resulting in a significant impact on their photovoltaic performance. In this work, four ladder-type tetra-p-phenylene containing copolymers with different alkyl side chains (P3FTBT1, P3FTBT1F, P3FTBT8O6 and P3FTBT1O6) were designed and synthesized. These copolymers have large bandgaps (∼2.0 eV) and deep-lying highest occupied molecular orbital (HOMO) energy levels (from −5.44 eV to −5.53 eV). The substitution of two hexyl groups with two methyl groups on the ladder-type tetra-p-phenylene unit afforded polymer P3FTBT1 which exhibits an enhanced power conversion efficiency (PCE) of 5.39%. Incorporation of fluorine into the benzo[c][1,2,5]thiadiazole (BT) unit gave polymer P3FTBT1F which exhibits a PCE of 4.50% with an open circuit voltage (Voc) of 1.09 V. By introducing two alkoxy groups to the BT unit, P3FTBT1O6 was synthesized, and it exhibits a PCE of 5.73% with a Voc of 1.02 V. The results suggest that the ladder-type tetra-p-phenylene is an excellent building block to construct donor–acceptor copolymers with high PCEs and large Vocs.
Co-reporter:Zhigang Yin, Wenbin Fan, Yunhai Ding, Jiaxin Li, Lunhui Guan, and Qingdong Zheng
ACS Sustainable Chemistry & Engineering 2015 Volume 3(Issue 3) pp:507
Publication Date(Web):January 21, 2015
DOI:10.1021/sc500755d
Polypyrrole (PPy)-modified CuO nanocomposites (NCs) with various shell structures have been synthesized by controlling the polymerization time of pyrrole in the presence of leaf-like CuO nanobelts (NBs) as wire templates. The synthesized CuO/PPy NCs and CuO NBs are characterized by XRD, FT–IR, TGA, SEM, TEM, STEM, and EDX line analysis/elemental mapping. The formation mechanism of CuO/PPy core–shell NCs is also illustrated. Electrochemical lithium-storage properties of all the products are evaluated by using them as anode materials for Li-ion batteries (LIBs). It is found that the polymerization time of pyrrole plays a significant role in affecting the shell structures and subsequent lithium-storage properties of the hybrid CuO/PPy NCs. With the extension of polymerization time, CuO/PPy NCs gradually form typical core–shell structures, where the doped PPy with increasing content is steadily and uniformly coated on the CuO surface. Correspondingly, the discharge/charge capacity and cyclic durability of CuO/PPy NCs are significantly enhanced. For the core–shell NCs made by the 3 h polymerization, a greatly improved initial capacity of 1114 mAh g–1 and a high reversible capacity of 760 mAh g–1 are achieved, which are much better than those of the bare CuO NBs and the NCs without core–shell structures. The improved performance of core–shell CuO/PPy NCs can be attributed to their advantageous structure features that buffer volume variations of the rigid CuO, allow short Li-ion diffusion length, form good interface interaction between PPy and CuO for charge transfer, and avoid direct contacts between CuO and electrolytes during charge–discharge processes. This study indicates that the structural tuning of polymer/metal oxide composites by controlling the polymerization time is a simple and promising way to improve the electrode performance of NCs for energy storage.Keywords: Composite materials; Conducting polymers; Electrochemical properties; Green synthesis; Lithium-ion batteries; Metal oxides; Polymerization
Co-reporter:Changquan Tang, Ping Hu, En Ma, Mingdong Huang, Qingdong Zheng
Dyes and Pigments 2015 Volume 117() pp:7-15
Publication Date(Web):June 2015
DOI:10.1016/j.dyepig.2015.01.019
•Five two-photon photosensitizers have been synthesized and characterized.•The photosensitizers with heavy atoms show enhanced 1O2 generation efficiencies.•A maximum TPA cross-section value up to 2707 GM is achieved.A series of indenofluorene-based two-photon absorbing chromophores (FL0, FL-2BrN, FL-1IN, FL-2IN, and FL-2IS) have been designed and synthesized for photodynamic therapy (PDT). Two-photon absorption (TPA) properties of these chromophores are determined and their structure-property relationship has been established. By incorporating electron withdrawing halogen atoms (such as Br, I) into the π-conjugation backbone of the chromophores, enhanced TPA cross-section values up to 2707 GM were achieved due to the formation of a donor-acceptor-donor (D-A-D) motif. At the same time, upon excitation at 430 nm, 2.2–4.1 times of enhancement in the singlet oxygen generation yield was observed for the photosensitizers with the heavy atoms incorporated. The photosensitizers with heavy atoms also show increased singlet oxygen generation efficiencies upon two-photon excitation at 808 nm, compared to those photosensitizers without heavy atoms. Photocytotoxicity of FL-2IN against cancer cells via two-photon excitation (808 nm) demonstrated that the indenofluorene-based chromophores are effective singlet oxygen donors for two-photon PDT.A series of novel indenofluorene-based chromophores have been designed as singlet oxygen (1O2) generators for two-photon photodynamic therapy (PDT). Both the 1O2 generation efficiencies and two-photon absorption are enhanced by incorporating heavy atoms (such as Br, I) into the π-conjugation backbone of the chromophores.
Co-reporter:Dhanavel Ganeshan, Shan-Ci Chen, Zhigang Yin and Qingdong Zheng
RSC Advances 2015 vol. 5(Issue 21) pp:16153-16161
Publication Date(Web):26 Jan 2015
DOI:10.1039/C4RA15343J
We systematically studied the plasmonic effects in polymer solar cells (PSCs) by using an anode buffer layer, in which size-controlled silver nanoparticles (NPs) (diameter: 4, 28, 55, and 75 nm, respectively) are incorporated into poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The optical properties of the buffer layer as well as the device performance of the resulting devices were investigated. We found that Ag NPs with an average diameter of 55 nm showed good behavior on enhancing light absorption due to the plasmonic scattering effect. Subsequently, the power conversion efficiency (PCE) of the PSC with Ag NPs (55 nm) improves to as high as 9.45% in comparison with a value of 7.90% for the control device without Ag NPs. In addition, the open circuit voltage, photocurrent and fill factor are simultaneously increased. The external quantum efficiency and light absorption are significantly enhanced in the range of ∼400–550 nm as compared to the control device. These results demonstrate that embedding Ag NPs into PSCs offers an effective strategy to improve the performance of optoelectronic devices.
Co-reporter:Lingcheng Chen, Kaichen Zhang, Changquan Tang, Qingdong Zheng, and Yi Xiao
The Journal of Organic Chemistry 2015 Volume 80(Issue 3) pp:1871-1877
Publication Date(Web):January 9, 2015
DOI:10.1021/jo5028529
By a controllable and stepwise strategy, a soluble ladder-conjugated perylene derivative BPI-FBI as the only product has been synthesized, which avoids the tough work to isolate regioisomers generated by a conventional one-step condensation method. BPI-FBI exhibits broad absorption spectra covering the whole visible region from 300 to 700 nm because of the large π-conjugation skeleton and has a low LUMO level inheriting the prototype PDI. In the steady-state space-charge-limited current (SCLC) devices, BPI-FBI exhibits an intrinsic electron mobility of 1.01 × 10–5 cm2 V–1 s–1. With a high two photon absorbing activity in the near-infrared region from 1200 to 1400 nm, BPI-FBI also exhibits good optical limiting performance, which will be useful for sensor or human eye protection and stabilization of light sources for optical communications.
Co-reporter:Hao Qin, Dongdong Cai, Meng Wang, Yunlong Ma, Zhigang Yin, Changquan Tang, Shan-Ci Chen, Qingdong Zheng
Polymer 2015 Volume 67() pp:258-266
Publication Date(Web):12 June 2015
DOI:10.1016/j.polymer.2015.04.079
•Dialkoxynaphthalene was used as an aromatic building block for polymer solar cells.•Three copolymers with different bandgaps and HOMO energy levels were synthesized.•Polymer solar cells based on PNDTBT exhibit a PCE of 6.24% with a Voc of 0.94 V.Dialkoxynaphthalene is a simple aromatic building block, which can be synthesized easily in a large scale. In this work, two dialkoxynaphthalene derivatives were copolymerized with electron-withdrawing benzothiadiazole (BT) derivatives to afford three donor-acceptor copolymers, PNDTBT, PNT2FTBT and PN2FTBT. The three copolymers have diverse bandgaps ranged from 1.73 to 1.86 eV, and deep HOMO energy levels up to −5.61 eV. Thermogravimetric analysis and electrochemical measurements show that these copolymers have good thermal and environment stability. The hole mobilities of these copolymers were investigated using the space charge limited current (SCLC) method as well as the organic field effect transistor (OFET) method. Polymer solar cells based on PNDTBT exhibit the best photovoltaic performance with a power conversion efficiency of 6.24% and a Voc of 0.94 V, much better than those of previously reported copolymers based on dialkoxynaphthalene.
Co-reporter:Zhigang Yin;Shan-Ci Chen;Jiaxin Li;Dongdong Cai
Nano Research 2015 Volume 8( Issue 2) pp:456-468
Publication Date(Web):2015 February
DOI:10.1007/s12274-014-0615-8
Highly efficient and stable polymer solar cells (PSCs) have been fabricated by adopting solution-derived hybrid poly(ethylene glycol)-titanium oxide (PEG-TiOx) nanocomposite films as a novel and universal cathode buffer layer (CBL), which can greatly improve device performance by reducing interface energy barriers and enhancing charge extraction/collection. The performance of inverted PSCs with varied bulk-heterojunctions (BHJs) based on this hybrid nanocomposite CBL was found to be much better than those of control devices with a pure TiOx CBL or without a CBL. An excellent power conversion efficiency up to 9.05% under AM 1.5G irradiation (100 mW·cm−2) was demonstrated, which represents a record high value for inverted PSCs with TiOx-based interface materials.
Co-reporter:Zhigang Yin;Shan-Ci Chen;Dongdong Cai;Lingyu Zhou;Jian Zhang
Advanced Energy Materials 2014 Volume 4( Issue 7) pp:
Publication Date(Web):
DOI:10.1002/aenm.201301404
Co-reporter:Yunlong Ma, Qingdong Zheng, Lixin Wang, Dongdong Cai, Changquan Tang, Meng Wang, Zhigang Yin and Shan-Ci Chen
Journal of Materials Chemistry A 2014 vol. 2(Issue 34) pp:13905-13915
Publication Date(Web):19 Jun 2014
DOI:10.1039/C4TA02585G
A ladder-type angular-shaped dithienonaphthalene (aDTN), an isomer of ladder-type linear-shaped dithienonaphthalene (DTN), was designed and synthesized as an electron-rich unit to construct donor–acceptor copolymers with deep-lying highest occupied molecular orbital (HOMO) energy levels. Benzo[c][1,2,5]thiadiazole (BT) with various substituents were used as electron deficient units for synthesizing the target copolymers (PaDTNBTO, PaDTNBTH, and PaDTNBTF) via the Stille coupling reaction. Incorporating different substituents onto the BT moiety has significant effects on the photophysical and electrochemical properties of the copolymers, as well as on the roughness of the polymer/PC71BM blends. With four solubilizing alkyl chains on the aDTN unit, all its three copolymers have good solubility in common solvents. The synthesized copolymers exhibit deep-lying HOMO energy levels, leading to high open circuit voltages (Voc ≥ 0.90 V) of the resulting polymer solar cells. The bulk heterojunction solar cell based on the aDTN-containing copolymers (PaDTNBTO) shows an improved efficiency of 6.44% and an increased Voc of 0.92 V compared to that based on the linear-shaped DTN containing counterpart (efficiency = 4.78%, Voc = 0.86 V). Whereas, under the same device fabrication conditions, PaDTNBTH- and PaDTNBTF-based devices exhibit efficiencies of 5.22% and 1.73%, respectively. Our results demonstrate that aDTN is a better building block in constructing p-type copolymers for high open circuit voltage devices compared to the linear-shaped DTN.
Co-reporter:Lixin Wang, Dongdong Cai, Zhigang Yin, Changquan Tang, Shan-Ci Chen and Qingdong Zheng
Polymer Chemistry 2014 vol. 5(Issue 23) pp:6847-6856
Publication Date(Web):20 Aug 2014
DOI:10.1039/C4PY00951G
Three donor–acceptor alternating copolymers abbreviated as PC1, PC2, and PC3, respectively, were designed and synthesized using diindenocarbazole (DIC) and dithienylbenzothiadiazole (DTBT) units. Through backbone manipulation, copolymers with large bandgaps (∼2.0 eV) and deep-lying HOMO energy levels (below −5.41 eV) were obtained. The side chains were also investigated to tune the intermolecular interactions and morphology of the copolymers blended with PC71BM. Polymer solar cells (PSCs) based on PC2:PC71BM exhibit an outstanding power conversion efficiency (PCE) of 7.26%, which represents one of the highest PCEs ever reported for PSCs while combining an open-circuit voltage (Voc) of 0.93 V and a large optical bandgap of 2.01 eV. Under similar device fabrication conditions, regular PSCs based on PC1 and PC3 achieve PCEs of 2.45% and 6.68%, respectively. Moreover, inverted PSCs derived from PC2 also exhibit an attractive PCE of 6.17% with a high Voc of 0.92 V. In view of its similar optical profiles to P3HT, but a deeper-lying HOMO energy level, PC2 should be a promising candidate as a short wavelength absorbing material for tandem solar cells.
Co-reporter:Wenbin Fan, Zhigang Yin, Yunlong Ma, Bingxi Wang, Shanci Chen, Changquan Tang, Qingdong Zheng
Polymer 2014 Volume 55(Issue 9) pp:2262-2270
Publication Date(Web):25 April 2014
DOI:10.1016/j.polymer.2014.03.017
We report on the synthesis and characterization of a series of donor–acceptor copolymers (PF1, PF2, PF3 or PF4) based on a dinaphtho-s-indacene (DNI) donor unit and four different acceptor units. The molecular weights of the copolymers were determined by using gel permeation chromatography, and their electrochemical properties were investigated by cyclic voltammetry. All four copolymers showed deep-lying highest occupied molecular orbital energy levels. Inverted bulk heterojunction solar cells were fabricated by using the synthesized copolymers as the electron donor material and 6,6-phenyl-C71-butyric acid methyl ester (PC71BM) as the electron acceptor material. Inverted solar cells based on PF1:PC71BM (1:4, w/w) exhibited a power conversion efficiency (PCE) of 3.07%, a high open-circuit voltage (Voc) of 0.99 V, a short-circuit current density (Jsc) of 7.85 mA/cm2, and a fill factor of 39.5% under the AM1.5G illumination. With the same fabrication method, the inverted devices based on PF2, PF3 and PF4 showed PCEs of 2.62, 1.18 and 1.32%, and Voc values of 0.97, 0.91 and 0.80 V, respectively.A series of dinaphtho-s-indacene based donor-acceptor copolymers (PF1, PF2, PF3 and PF4) with deep-lying HOMO energy levels were synthesized, and they were used as donor materials to fabricate inverted solar cells. The solar cells based on PF1 show a PCE of 3.07%, with a high Voc of 0.99 V.
Co-reporter:Changquan Tang, Qingdong Zheng, Haomiao Zhu, Lixin Wang, Shan-Ci Chen, En Ma and Xueyuan Chen
Journal of Materials Chemistry A 2013 vol. 1(Issue 9) pp:1771-1780
Publication Date(Web):04 Jan 2013
DOI:10.1039/C2TC00780K
A series of soluble ladder-type tetraphenylene cored chromophores with different terminal groups have been synthesized and their structure–property relationship with regards to various linear optical and nonlinear optical properties has been established. By using the two-photon excited fluorescence method and the nonlinear transmission method, the two-photon absorption (2PA) properties of these chromophores were determined, and they were found to be strongly dependent on the electron-richness of the ladder-type tetraphenylene core, as well as the terminal groups. The introduction of strong electron donors (N-alkyl) in both the central core and the terminals led to a chromophore with a high 2PA cross-section value of 2137 GM. Optical limiting behaviors of the synthesized chromophores in THF were investigated by using a femto-second ultra-fast laser. 2PA coefficients for these chromophores in THF (5 mM) ranged from 0.131–0.256 cm GW−1. The ladder-type tetraphenylene cored chromophore with the highest 2PA cross-section value exhibited the best optical limiting performance, as evidenced by light transmission as low as 19.1% at 770 nm under an intensity of 99.6 GW cm−2. The excellent optical limiting performance of these chromophores makes them useful in photonic or optoelectronic devices for protecting human eyes and optical sensors, as well as for stabilizing light sources in optical communications.
Co-reporter:Zhigang Yin, Qingdong Zheng, Shan-Ci Chen, and Dongdong Cai
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 18) pp:9015
Publication Date(Web):August 28, 2013
DOI:10.1021/am402175m
Inverted polymer solar cells (PSCs) with high open-circuit voltages of 1.00–1.06 V are fabricated by using an indenofluorene-containing copolymer (PIFTBT8) as an electron donor material and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as an electron acceptor material. To improve the photovoltaic performance, interface control of various low-temperature processed ZnO films as cathode buffer layers is systematically investigated for effective electron transportation, while transition metal oxides including MoO3, WO3, NiO, and Cu2O are employed as anode buffer layers for hole-extraction. Incorporation of optimized semiconducting metal oxide interlayers can minimize interfacial power losses, which thus affords large open-circuit voltages (Voc), increased short-circuit current densities (Jsc), and fill factors (FF), eventually contributing to higher power conversion efficiencies (PCEs) as well as better device stability. Due to the improved interfacial contacts and fine-matching energy levels, inverted PSCs with a device configuration of ITO/ZnO/PIFTBT8:PC71BM/MoO3/Ag exhibit a high PCE of 5.05% with a large Voc of 1.04 V, a Jsc of 9.74 mA cm–2, and an FF of 50.1%. For the single junction inverted PSCs with efficiencies over 5.0%, 1.04 V is the largest Voc ever achieved. By controlling the processing conditions of the active layer, the Voc can further be improved to 1.05 and 1.06 V, with PCEs of 4.70% and 4.18%, respectively. More importantly, the inverted PSCs are ascertained to maintain a PCE of 4.55% (>90% of its initial efficiency) and a Voc of 1.05 V over 180 days, demonstrating good long-term stability, which is much better than that of the conventional devices. The results suggest that the interface engineering of metal oxide interlayers is an important strategy to develop PSCs with good performance.Keywords: device stability; high open-circuit voltages; interface engineering; inverted polymer solar cells; metal oxides;
Co-reporter:Lixin Wang, Dongdong Cai, Qingdong Zheng, Changquan Tang, Shan-Ci Chen, and Zhigang Yin
ACS Macro Letters 2013 Volume 2(Issue 7) pp:605
Publication Date(Web):June 21, 2013
DOI:10.1021/mz400185k
Two novel copolymers incorporating N-alkyl-4,7-di(thien-2-yl)-2,1,3-benzothiadiazole-5,6-dicarboxylic imide (DI) and benzo[1,2-b:4,5-b′]dithiophene (BDT) units have been designed, synthesized, and characterized. By the incorporation of the DI unit, both polymers show a bathochromically shifted absorption with a deep lying highest occupied molecular orbital (HOMO) energy level. The polymer based on thienyl group substituted BDT exhibits an intense absorption in the longer-wavelength region, a deeper lying HOMO energy level, and a higher carrier mobility, all of which contribute to the resulting polymer solar cells with a higher power conversion efficiency (PCE) of 5.19% and an increased Voc of 0.91 V.
Co-reporter:Xiaoyang Yang, Qingdong Zheng, Changquan Tang, Dongdong Cai, Shan-Ci Chen, Yunlong Ma
Dyes and Pigments 2013 Volume 99(Issue 2) pp:366-373
Publication Date(Web):November 2013
DOI:10.1016/j.dyepig.2013.05.013
•A truxene based planar electron-rich core was designed and synthesized.•A series of star-shaped chromophores with various terminal groups were prepared.•Organic solar cells based on the chromophores exhibit Voc in the range of 0.86–1.07 V.•The best power conversion efficiency of 2.40% has been achieved.By fusing three benzodithiophenes with a truxene, a new planar aromatic electron-rich core was synthesized, which was used for the construction of novel star-shaped chromophores with various terminal groups. The absorption maxima of the synthesized star-shaped chromophores in thin film are varied from 366 nm to 527 nm depending on the electron donating/accepting properties of the terminal groups. Bulk heterojunction (BHJ) photovoltaic devices were fabricated by using the star-shaped chromophores as donor materials and (6, 6)-phenyl C71-butyric acid methyl ester (PC71BM) as an acceptor material. The fabricated solar cells showed open circuit voltages (Voc) in the range of 0.86–1.07 V, which are related with the energy difference between HOMO energy levels of the chromophores and the LUMO energy level of PC71BM. BHJ photovoltaic devices based on one of these star-shaped chromophores exhibit a power conversion efficiency of 2.40% without extended optimization.
Co-reporter:Shan-Ci Chen, Dhanavel Ganeshan, Dongdong Cai, Qingdong Zheng, Zhigang Yin, Fei Wang
Organic Electronics 2013 Volume 14(Issue 11) pp:2859-2865
Publication Date(Web):November 2013
DOI:10.1016/j.orgel.2013.08.015
•A new class of n-type organic semiconductors for high performance OFETs.•Angular-shaped naphthalene diimides were used as active layer in devices.•The highest electron mobility of 0.515 cm2/V s was obtained.•The device performance was correlated with the film crystallinity and morphology.We report on the performance of organic field-effect transistors (OFETs) by using a series of angular-shaped naphthalene tetracarboxylic diimides as active layers. The fabricated OFET devices exhibit n-type semiconducting characteristics. The performance of OFETs can be substantially improved by modifying the surface of the gate dielectric chemically prior to the deposition of the organic semiconductors. An increased electron mobility of the OFETs was found owing to the improved crystallinity and enlarged grain sizes, which are attributed to the elevating substrate temperature during the semiconductor deposition. The highest mobility of 0.515 cm2/V s was achieved from a device fabricated at substrate temperature of 130 °C with octadecyltrichlorosilane (OTS) surface modification.Graphical abstract
Co-reporter:Shanci Chen;Changquan Tang;Zhigang Yin;Yunlong Ma;Dongdong Cai;Dhanavel Ganeshan
Chinese Journal of Chemistry 2013 Volume 31( Issue 11) pp:1409-1417
Publication Date(Web):
DOI:10.1002/cjoc.201300500
Abstract
A ladder-type diindenopyrazine (IPY) was synthesized and used as a building block for constructing conjugated copolymers. Three copolymers based on the IPY moiety were obtained via the Suzuki coupling reaction with different monomers, including 4,7-dithien-2-yl-2,1,3-benzothiadiazole (DBT), 5,8-dithien-2-yl-2,3-diphenylquinoxaline (DTQ), and 5,8-dithien-2-yl-2,3-di(4-fluorophenyl)quinoxaline (DFTQ). The obtained polymers were characterized by 1H NMR spectroscopy, UV-Vis absorption spectroscopy, cyclic voltammetry, and gel permeation chromatography (GPC). Owing to the four solubilizing alkyl chains on the IPY unit, all the three copolymers have good solubility in common solvents. These polymers have deep-lying HOMO energy levels in the range of −5.55–−5.60 eV, and exhibit ?eld-effect mobilities as high as 0.006 cm2·V−1·s−1. Photovoltaic applications of these polymers as light-harvesting and hole-conducting materials were investigated in conjunction with [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM). Both conventional and inverted devices were fabricated based on these three polymers. A power conversion efficiency (PCE) of 2.53% and a high open-circuit voltage of 1.00 V were obtained under simulated solar light AM 1.5 G (100 mW/cm2) from an inverted solar cell with an active layer containing 25 wt% ladder-type IPY containing copolymer (PIPYDTQ) and 75 wt% PC61BM. Moreover, a high open-circuit voltage of 1.02 V and a PCE of 2.40% were achieved from a conventional solar cell based on PIPYDTQ.
Co-reporter:Shan-Ci Chen;Qikai Zhang;Dongdong Cai;Jinyun Wang;Zhigang Yin ;Changquan Tang
Journal of Polymer Science Part A: Polymer Chemistry 2013 Volume 51( Issue 9) pp:1999-2005
Publication Date(Web):
DOI:10.1002/pola.26580
Abstract
An angular-shaped naphthalene tetracarboxylic diimide (NDI) was designed and synthesized as a new building block for n-type conjugated polymers to tune their energy levels. Three n-type copolymers incorporating this angular-shaped NDI as the acceptor moiety were obtained by Stille coupling reactions and had number average molecular weights of 18.7–73.0 kDa. All-polymer bulk-heterojunction solar cells made from blends of these polymers with poly(3-hexylthiophene) gave a power conversion efficiency up to 0.32% and exhibited an open-circuit voltage (Voc) up to 0.94 V due to their relative high-lying lowest unoccupied molecular orbital energy levels. The high Voc of 0.94 V is higher than that of solar cells based on linear-shaped NDI-containing polymers (<0.6 V). The results indicate that the angular-shaped NDI is a promising building block for constructing nonfullerene polymer acceptors for solar cells with high open-circuit voltages. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
Co-reporter:Yunlong Ma, Qingdong Zheng, Zhigang Yin, Dongdong Cai, Shan-Ci Chen, and Changquan Tang
Macromolecules 2013 Volume 46(Issue 12) pp:4813-4821
Publication Date(Web):June 5, 2013
DOI:10.1021/ma400696e
A novel ladder-type dithienonaphthalene (DTN) was designed and synthesized as an electron-rich unit for constructing donor–acceptor copolymers. Different acceptor moieties, including benzo[c][1,2,5]thiadiazole (BT), 5,6-bis(hexyloxy)-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole (TBT), and 2,5-bis(2-ethylhexyl)-3,6-di(thiophen-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (TDPP), were used as electron-deficient units for the target copolymers. These copolymers (PDTNBT, PDTNTBT, and PDTNTDPP) were obtained via the Stille coupling reaction and characterized by 1H NMR spectroscopy, UV–vis absorption spectroscopy, cyclic voltammetry, and gel permeation chromatography (GPC). Owing to the four solubilizing alkyl chains on the DTN unit, all the three copolymers have good solubility in common solvents. Among these polymers, PDTNTBT exhibits the highest space-charge limit current (SCLC) hole mobility of 2.13 × 10–5 cm2 V–1 s–1, which is beneficial for achieving high performance solar cells. Under the simulated AM 1.5G illumination condition (100 mW/cm2), solar cells based on PDTNTBT:PC71BM (1:3, w/w) exhibit a power conversion efficiency (PCE) of 4.8% with a current density of 10.3 mA cm–2, an open-circuit voltage of 0.86 V, and a fill factor of 54%. With the same device fabrication method, PDTNTDPP:PC71BM (1:3, w/w) and PDTNBT:PC71BM (1:3, w/w) based devices exhibit efficiencies of 1.52% and 2.79%, respectively. Furthermore, inverted solar cells based on these copolymer blends are also fabricated. The inverted devices based on PDTNTDPP:PC71BM (1:2, w/w) and PDTNBT:PC71BM (1:2, w/w) exhibit PCEs of 1.60% and 2.89%, respectively, which are similar to their corresponding conventional devices. And the inverted devices based on PDTNTBT:PC71BM (1:2, w/w) show a higher PCE of 5.0%, and more importantly, they are quite stable as demonstrated by the 4.75% PCE after ambient storage for two months.
Co-reporter:Zhigang Yin
Advanced Energy Materials 2012 Volume 2( Issue 2) pp:179-218
Publication Date(Web):
DOI:10.1002/aenm.201100560
Abstract
The past decade has witnessed increasing attention in the synthesis, properties, and applications of one-dimensional (1D) conducting polymer nanostructures. This overview first summarizes the synthetic strategies for various 1D nanostructures of conjugated polypyrrole (PPy), polyaniline (PANI), polythiophene (PTh), poly(p-phenylenevinylene) (PPV) and derivatives thereof. By using template-directed or template-free methods, nanoscale rods, wires/fibers, belts/ribbons, tubes, arrays, or composites have been successfully synthesized. With their unique structures and advantageous characteristics (e.g., high conductivity, high carrier mobility, good electrochemical activity, large specific surface area, short and direct path for charge/ion transportation, good mechanical properties), 1D conducting polymer nanostructures are demonstrated to be very useful for energy applications. Next, their applications in solar cells, fuel cells, rechargeable lithium batteries, and electrochemical supercapacitors are highlighted, with a strong emphasis on recent literature examples. Finally, this review ends with a summary and some perspectives on the challenges and opportunities in this emerging area of research.
Co-reporter:Dongdong Cai, Qingdong Zheng, Shan-Ci Chen, Qikai Zhang, Can-Zhong Lu, Yu Sheng, Deqin Zhu, Zhigang Yin and Changquan Tang
Journal of Materials Chemistry A 2012 vol. 22(Issue 31) pp:16032-16040
Publication Date(Web):14 Jun 2012
DOI:10.1039/C2JM31638B
Four semiconducting copolymers were designed and synthesized based on a novel ladder-type heteroheptacene building block, which was prepared in four steps from 3,7-dibromodibenzo[b,d]thiophene. The copolymers were characterized by 1H NMR spectroscopy, UV-Vis absorption spectroscopy, cyclic voltammetry and their molecular weights were estimated using gel permeation chromatography. Field effect transistors (FETs) fabricated from these four polymers exhibit semiconducting behavior in air. The highest mobility of 2.21 × 10−4 cm2 V−1 s−1 was found in the polymer copolymerized from the ladder-type heteroheptacene and terthiophene. Low band-gap donor–acceptor copolymers with a deep-lying HOMO energy level were synthesized by a copolymerization between the ladder-type heteroheptacene donor and the 2,1,3-benzothiadiazole acceptor. Polymer solar cells made from one of these polymers gave a power conversion efficiency of 4.17%, a current density of 9.2 mA cm−2, an open-circuit voltage of 0.79 V, and a fill factor of ∼57.4% under 100 mW cm−2 AM 1.5 G sunlight illumination.
Co-reporter:Shan-ci Chen, Qikai Zhang, Qingdong Zheng, Changquan Tang and Can-Zhong Lu
Chemical Communications 2012 vol. 48(Issue 9) pp:1254-1256
Publication Date(Web):16 Dec 2011
DOI:10.1039/C2CC15733K
A series of compounds based on the angular-shaped naphthalene tetracarboxylic diimide core have been synthesized, characterized and used as active layers of organic field-effect transistors (OFETs). The fabricated OFET devices exhibit n-type semiconducting characteristics, demonstrating the first examples of semiconductors based on angular-shaped naphthalene tetracarboxylic diimides.
Co-reporter:Xuehua Hong, Zhuyuan Wang, Jing Yang, Qingdong Zheng, Shenfei Zong, Yu Sheng, Deqin Zhu, Changquan Tang and Yiping Cui
Analyst 2012 vol. 137(Issue 18) pp:4140-4149
Publication Date(Web):12 Jun 2012
DOI:10.1039/C2AN35389J
Two silylated BODIPY derivatives were synthesized, characterized and used for the fabrication of the dye-encapsulated silica nanoparticles. The fluorophores were covalently incorporated into the silica matrix to minimize any fluorophore leakage. The synthesized fluorophore-doped nanoparticles were stable in aqueous solution and monodisperse with diameters of 20–25 nm. By incorporating the two BODIPY dyes simultaneously at a controlled ratio, silica nanoparticles with switchable emitting wavelengths were achieved with a change in the excitation wavelength. Thus by using the dual-fluorophore-doped nanoparticles, two-color imaging was demonstrated with minimal background signal by employing an appropriate excitation light source and appropriate excitation/emission filter sets. Further, the surfaces of the dual-fluorophore-doped nanoparticles were functionalized with folic acid to allow for the recognition of HeLa cells which over-express the folate receptors.
Co-reporter:Zhigang Yin, Yunhai Ding, Qingdong Zheng, Lunhui Guan
Electrochemistry Communications 2012 20() pp: 40-43
Publication Date(Web):
DOI:10.1016/j.elecom.2012.04.005
Co-reporter:Jia Huang, Zhigang Yin and Qingdong Zheng
Energy & Environmental Science 2011 vol. 4(Issue 10) pp:3861-3877
Publication Date(Web):19 Aug 2011
DOI:10.1039/C1EE01873F
As an n-type inorganic semiconductor, ZnO has been widely used in organic solar cells (OSCs) and hybrid solar cells (HSCs) due to its salient characteristics such as low cost, easy synthesis, non-toxicity, high stability, and good optoelectronic properties. This article reviews the applications of ZnO in solar cells, including ZnO/organic HSCs, and OSCs with ZnO acting as electrode buffer layers or transparent electrodes. For ZnO/organic HSCs, ZnO serves as the electron acceptor material, while organic semiconductors act as electron donor materials. For the buffer layers or electrode applications, ZnO is used as an electron collection and hole blocking material where its structure plays an important role in the determination of the device performance (e.g., power conversion efficiency, lifetime, stability, etc.). Special emphasis goes to the device performance of OSCs and HSCs, which depends not only on the active materials and the device configurations, but also on the structural characteristics of the ZnO buffer layer. Finally, we briefly give an analysis on the opportunities and challenges for this promising semiconductor in OSCs and HSCs.
Co-reporter:Yunlong Ma, Shan-Ci Chen, Zaiyu Wang, Wei Ma, Jinyun Wang, Zhigang Yin, Changquan Tang, Dongdong Cai, Qingdong Zheng
Nano Energy (March 2017) Volume 33() pp:
Publication Date(Web):March 2017
DOI:10.1016/j.nanoen.2017.01.050
•A novel hybrid electron transport layer (PDIN: PFN) is used for polymer solar cells.•Two wide bandgap indacenodithiophene-based copolymers are designed and synthesized.•A fibrous network is formed for the active layer based on the copolymer PIDTBTO-TT.•The best performance tandem device exhibits a power conversion efficiency of 11.15%.Two wide bandgap copolymers based on bulky indacenodithiophene (IDT) and alkoxylated benzothiadiazole units (PIDTBTO-T and PIDTBTO-TT) with the thiophene or thieno[3,2-b]thiophene (TT) π-bridge are designed and synthesized. The effect of π-bridge on the π-π packing, optical, carrier transport, nano-sized phase separation and photovoltaic properties of the copolymers are investigated in depth. In comparison with the PIDTBTO-T-based counterpart, the best performance solar cell based on PIDTBTO-TT exhibits a higher power conversion efficiency (PCE) of 8.15% which is mainly attributed to the formation of a fibrous network for the active layer based on PIDTBTO-TT. Furthermore, when a novel hybrid electron transport layer (PDIN:PFN) is introduced into a tandem solar cell using the PIDTBTO-TT-based device and a PTB7-Th-based device as the bottom and top cell components, respectively, the resulting solar cell exhibits an outstanding PCE of 11.15% with a large open circuit voltage of 1.70 V. To the best of our knowledge, the PCEs of 8.15% and 11.15% are the highest values reported to date for the single-junction and tandem solar cells using IDT-based copolymers, respectively. Our results demonstrate that the π-bridge modulation is effective in adjusting the charge carrier mobility and photovoltaic performance of IDT-based wide bandgap copolymers for single-junction and tandem devices.
Co-reporter:Meng Wang, Dongdong Cai, Jingming Xin, Wei Ma, Qisheng Tu and Qingdong Zheng
Journal of Materials Chemistry A 2017 - vol. 5(Issue 24) pp:NaN12021-12021
Publication Date(Web):2017/05/30
DOI:10.1039/C7TA03316H
Ternary conjugated D–A copolymers are designed and synthesized by using indenothiophene and benzodithiophene as the weak and the strong donors, respectively, and fluorinated benzodithiazole as the strong acceptor. The best performance copolymer delivers a high PCE of 9.08%, which is a record efficiency for ternary conjugated D–A copolymers reported to date.
Co-reporter:Zhigang Yin, Jiajun Wei, Shan-Ci Chen, Dongdong Cai, Yunlong Ma, Meng Wang and Qingdong Zheng
Journal of Materials Chemistry A 2017 - vol. 5(Issue 8) pp:NaN3899-3899
Publication Date(Web):2017/01/09
DOI:10.1039/C6TA10981K
Semitransparent organic solar cells (STOSCs) have shown great promise as advanced window integrated photovoltaics for architectural and automotive utilization. In the applications, STOSCs should possess both long-term stability and high power conversion efficiency (PCE). Here, long lifetime stable and efficient STOSCs with good transparency color perception are demonstrated by combining a transparent ZnMgO-modified cathode with thin MoO3/Ag anodes. The resulting devices exhibit high PCEs (6.83–8.15%) with tunable average visible transmittances (21.6–3.8%) and good color perception close to white light. The combination of the ZnMgO-modified cathode with the MoO3/Ag anode in the STOSCs leads to long-term device shelf lifetime due to their barrier effects for oxygen and water. The STOSCs can maintain over 90% of their original PCEs over two-month storage under ambient conditions. More importantly, record high PCEs of 7.08% and 7.02% were retained for the STOSCs after storage for 1 year and 2 years, respectively, demonstrating the long lifetime stability for high-efficiency STOSCs. These findings offer a promising path to develop STOSCs with high efficiencies, long lifetime and good color perception towards practical applications.
Co-reporter:Yunlong Ma, Zhenjing Kang and Qingdong Zheng
Journal of Materials Chemistry A 2017 - vol. 5(Issue 5) pp:NaN1872-1872
Publication Date(Web):2016/12/15
DOI:10.1039/C6TA09325F
As key components in the active layer of multi-junction, ternary blend, or non-fullerene polymer solar cells (PSCs), wide bandgap semiconducting polymers have the characteristic of exhibiting strong absorption bands in the short-wavelength region. In multi-junction, ternary blend, or non-fullerene PSCs, wide bandgap polymers can provide complementary absorption profiles with low bandgap counterparts, thereby further increasing power conversion efficiencies. In this review, we summarize the recent advances of wide bandgap semiconducting polymers and their applications in PSCs, and discuss the designs as well as the material structure–property-device performance correlations. Finally, we conclude by highlighting the challenges and future developments of wide bandgap semiconducting polymers.
Co-reporter:Dongdong Cai, Qingdong Zheng, Shan-Ci Chen, Qikai Zhang, Can-Zhong Lu, Yu Sheng, Deqin Zhu, Zhigang Yin and Changquan Tang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 31) pp:
Publication Date(Web):
DOI:10.1039/C2JM31638B
Co-reporter:Changquan Tang, Qingdong Zheng, Haomiao Zhu, Lixin Wang, Shan-Ci Chen, En Ma and Xueyuan Chen
Journal of Materials Chemistry A 2013 - vol. 1(Issue 9) pp:NaN1780-1780
Publication Date(Web):2013/01/04
DOI:10.1039/C2TC00780K
A series of soluble ladder-type tetraphenylene cored chromophores with different terminal groups have been synthesized and their structure–property relationship with regards to various linear optical and nonlinear optical properties has been established. By using the two-photon excited fluorescence method and the nonlinear transmission method, the two-photon absorption (2PA) properties of these chromophores were determined, and they were found to be strongly dependent on the electron-richness of the ladder-type tetraphenylene core, as well as the terminal groups. The introduction of strong electron donors (N-alkyl) in both the central core and the terminals led to a chromophore with a high 2PA cross-section value of 2137 GM. Optical limiting behaviors of the synthesized chromophores in THF were investigated by using a femto-second ultra-fast laser. 2PA coefficients for these chromophores in THF (5 mM) ranged from 0.131–0.256 cm GW−1. The ladder-type tetraphenylene cored chromophore with the highest 2PA cross-section value exhibited the best optical limiting performance, as evidenced by light transmission as low as 19.1% at 770 nm under an intensity of 99.6 GW cm−2. The excellent optical limiting performance of these chromophores makes them useful in photonic or optoelectronic devices for protecting human eyes and optical sensors, as well as for stabilizing light sources in optical communications.
Co-reporter:Lixin Wang, Dongdong Cai, Changquan Tang, Meng Wang, Zhigang Yin and Qingdong Zheng
Journal of Materials Chemistry A 2015 - vol. 3(Issue 22) pp:NaN5641-5641
Publication Date(Web):2015/04/02
DOI:10.1039/C5TC00398A
We have developed a facile synthetic route to a ladder-type donor unit (SDCT) wherein two outer thiophene subunits are covalently fastened to the central dibenzothiophene core through two sp3-hybridized bridging carbons. An innovative transformation from an aryl ketone group to an aryl ester group was applied to construct the ladder-type molecular skeleton, and the overall synthetic yield toward the donor unit has been significantly improved by choosing aryl side chains instead of aliphatic ones to avoid competing dehydration reactions. To reveal the effects of π-spacers and heteroatom substituents, three donor–acceptor (D–A) copolymers containing SDCT and acceptor units of 2,1,3-benzothiadiazole (BT), 2,1,3-benzoxadiazole (BO), or 4,7-bis(2-thienyl)-2,1,3-benzothiadiazole (DTBT) were synthesized, characterized and used for polymer solar cells (PSCs). All polymers exhibit blue-shifted absorption spectra and deeper-lying HOMO energy levels compared to the previous carbazole-based skeleton analogues. In comparison with its analogous polymer with the same π-conjugated backbone, the polymer with alkoxy-substituted BT as the acceptor unit (PSBT) shows an order of magnitude higher OFET mobility (1.8 × 10−4versus 1.25 × 10−5 cm2 V−1 s−1). An optimal device based on PSBT:PC71BM (1/3 in wt%) delivers a respectable PCE of 5.18% and a high Voc of 0.94 V, all of which are superior to those of the carbazole-based analogue (PCE = 3.7%, Voc = 0.80 V) and greatly surpass the values of a previously reported dibenzothiophene-based polymer (PCE = 0.76%, Voc = 0.64 V). These results demonstrate that SDCT is a promising building block for constructing photovoltaic polymers and the synthetic strategy developed herein can be used to prepare other dibenzothiophene-cored ladder-type heptacyclic units.
Co-reporter:Qisheng Tu, Dongdong Cai, Lixin Wang, Jiajun Wei, Qi Shang, Shan-Ci Chen, Yunlong Ma, Zhigang Yin, Changquan Tang and Qingdong Zheng
Journal of Materials Chemistry A 2016 - vol. 4(Issue 25) pp:NaN6168-6168
Publication Date(Web):2016/06/02
DOI:10.1039/C6TC01778A
Five wide bandgap conjugated polymers based on diindenocarbazole (DIC) and dithienylbenzothiadiazole (DTBT) alternating units have been designed and prepared to investigate the effects of side chains on the photovoltaic performance of the polymers. All the polymers are soluble in common organic solvents and they show similar optical bandgaps of around 2.0 eV as well as deep-lying highest occupied molecular orbital (HOMO) energy levels (below −5.48 eV). Bulk heterojunction (BHJ) polymer solar cells (PSCs) using phenyl-C71-butyric acid methyl ester (PC71BM) as the electron acceptor material were fabricated. The side chains on the polymer backbone have a strong impact on the film morphology of the polymer:PC71BM blends. A phase separation with a relatively larger domain size was found for the polymers with longer side chains, while those with relatively shorter alkyl chains could form uniform films featuring a phase separation with a smaller domain size. Finally, PSCs based on PC1BT6:PC71BM exhibited an outstanding power conversion efficiency of 7.34% with a high open-circuit voltage (Voc) of 0.95 V. Our results demonstrate that the judicious design of side-chains is effective in improving the photovoltaic performance of DIC-based polymers. With a larger bandgap than P3HT but an improved power conversion efficiency (PCE) with a large Voc, this type of DIC-based polymer should be a promising bottom layer material for tandem solar cells.
Co-reporter:Yunlong Ma, Qingdong Zheng, Lixin Wang, Dongdong Cai, Changquan Tang, Meng Wang, Zhigang Yin and Shan-Ci Chen
Journal of Materials Chemistry A 2014 - vol. 2(Issue 34) pp:NaN13915-13915
Publication Date(Web):2014/06/19
DOI:10.1039/C4TA02585G
A ladder-type angular-shaped dithienonaphthalene (aDTN), an isomer of ladder-type linear-shaped dithienonaphthalene (DTN), was designed and synthesized as an electron-rich unit to construct donor–acceptor copolymers with deep-lying highest occupied molecular orbital (HOMO) energy levels. Benzo[c][1,2,5]thiadiazole (BT) with various substituents were used as electron deficient units for synthesizing the target copolymers (PaDTNBTO, PaDTNBTH, and PaDTNBTF) via the Stille coupling reaction. Incorporating different substituents onto the BT moiety has significant effects on the photophysical and electrochemical properties of the copolymers, as well as on the roughness of the polymer/PC71BM blends. With four solubilizing alkyl chains on the aDTN unit, all its three copolymers have good solubility in common solvents. The synthesized copolymers exhibit deep-lying HOMO energy levels, leading to high open circuit voltages (Voc ≥ 0.90 V) of the resulting polymer solar cells. The bulk heterojunction solar cell based on the aDTN-containing copolymers (PaDTNBTO) shows an improved efficiency of 6.44% and an increased Voc of 0.92 V compared to that based on the linear-shaped DTN containing counterpart (efficiency = 4.78%, Voc = 0.86 V). Whereas, under the same device fabrication conditions, PaDTNBTH- and PaDTNBTF-based devices exhibit efficiencies of 5.22% and 1.73%, respectively. Our results demonstrate that aDTN is a better building block in constructing p-type copolymers for high open circuit voltage devices compared to the linear-shaped DTN.
Co-reporter:Meng Wang, Hao Qin, Lixin Wang, Jiajun Wei, Dongdong Cai, Zhigang Yin, Yunlong Ma, Shan-Ci Chen, Changquan Tang and Qingdong Zheng
Journal of Materials Chemistry A 2015 - vol. 3(Issue 43) pp:NaN21681-21681
Publication Date(Web):2015/09/14
DOI:10.1039/C5TA04872A
Side-chain engineering of polymer backbones can induce subtle variations in polymer properties, resulting in a significant impact on their photovoltaic performance. In this work, four ladder-type tetra-p-phenylene containing copolymers with different alkyl side chains (P3FTBT1, P3FTBT1F, P3FTBT8O6 and P3FTBT1O6) were designed and synthesized. These copolymers have large bandgaps (∼2.0 eV) and deep-lying highest occupied molecular orbital (HOMO) energy levels (from −5.44 eV to −5.53 eV). The substitution of two hexyl groups with two methyl groups on the ladder-type tetra-p-phenylene unit afforded polymer P3FTBT1 which exhibits an enhanced power conversion efficiency (PCE) of 5.39%. Incorporation of fluorine into the benzo[c][1,2,5]thiadiazole (BT) unit gave polymer P3FTBT1F which exhibits a PCE of 4.50% with an open circuit voltage (Voc) of 1.09 V. By introducing two alkoxy groups to the BT unit, P3FTBT1O6 was synthesized, and it exhibits a PCE of 5.73% with a Voc of 1.02 V. The results suggest that the ladder-type tetra-p-phenylene is an excellent building block to construct donor–acceptor copolymers with high PCEs and large Vocs.
Co-reporter:Shan-ci Chen, Qikai Zhang, Qingdong Zheng, Changquan Tang and Can-Zhong Lu
Chemical Communications 2012 - vol. 48(Issue 9) pp:NaN1256-1256
Publication Date(Web):2011/12/16
DOI:10.1039/C2CC15733K
A series of compounds based on the angular-shaped naphthalene tetracarboxylic diimide core have been synthesized, characterized and used as active layers of organic field-effect transistors (OFETs). The fabricated OFET devices exhibit n-type semiconducting characteristics, demonstrating the first examples of semiconductors based on angular-shaped naphthalene tetracarboxylic diimides.
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