Co-reporter:Yunfeng Deng, Yagang Chen, Xiaojie Zhang, Hongkun Tian, Cheng Bao, Donghang Yan, Yanhou Geng, and Fosong Wang
Macromolecules November 13, 2012 Volume 45(Issue 21) pp:8621-8627
Publication Date(Web):November 13, 2012
DOI:10.1021/ma301864f
A series of donor–acceptor (D–A) conjugated polymers (CPs) comprising dithieno[2,3-b;7,6-b]carbazole (C1) or dithieno[3,2-b;6,7-b]carbazole (C2) as D unit and thienopyrroledione (TPD), isoindigo (IID), or diketopyrrolopyrrole (DPP) as A unit were synthesized, and their semiconducting properties were investigated with organic field-effect transistors (OFETs). Because of different bonding geometry of C1 and C2, the CPs based on these isomeric D units have distinct backbone conformation. The CPs based on C1 unit and all three A units show strong backbone curvature. In consequence, these polymers all formed amorphous films and exhibited low OFET mobility in the level of 10–3 cm2/(V s). P(TPD-C2) and P(DPP-C2), which comprise C2 and TPD or DPP, both display pseudo-straight-shaped backbones and formed ordered films with the polymer backbones adopting edge-on orientation respective to the substrates. Accordingly, P(TPD-C2) and P(DPP-C2) exhibited the highest mobility of 0.31 and 1.36 cm2/(V s), respectively. However, P(IID-C2) could only form amorphous films probably owing to its highly stiff backbone, leading to a moderate OFET mobility (2.96 × 10–2 cm2/(V s)). This implies that large fused aromatics are promising building blocks for high-mobility D–A CPs when polymer backbone conformation and rigidity are appropriately manipulated.
Co-reporter:Yunfeng Deng, Yagang Chen, Jian Liu, Lihui Liu, Hongkun Tian, Zhiyuan Xie, Yanhou Geng, and Fosong Wang
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 12) pp:5741
Publication Date(Web):May 29, 2013
DOI:10.1021/am401175v
Four donor–acceptor (D–A) conjugated polymers of dithieno[2,3-b;7,6-b]carbazole (DTC) and diketopyrrolopyrrole, which have different alkyls on the nitrogen atom in the DTC unit and are named as P-C8C8, P-C5C5, P-C12, and P-C10, respectively, have been synthesized for studying the effect of the alkyl side chains on the optoelectronic properties of the polymers. All polymers are soluble in various organic solvents and exhibit identical optical band gaps (Egopt) of ∼1.3 eV and highest occupied molecular orbital energy levels of ∼−5.1 eV. Organic thin-film transistors and bulk heterojunction polymer solar cells (BHJ PSCs) with phenyl-C71-butyric acid methyl ester (PC71BM) as the electron-accepting material were fabricated via solution spin-casting. Compared to the polymers substituted by branched alkyl chains, the polymers with straight alkyl chains show higher hole mobility. Of these polymers, P-C10 exhibits the highest field effect mobility up to 0.011 cm2/V·s. The alkyl chain on the DTC unit has a strong impact on the film morphology of polymer:PC71BM blends. Severe phase separation was found for polymers containing branched alkyl chains, and those with straight alkyl chains formed uniform films featuring fine phase separation. An open-circuit voltage (Voc) of 0.72 V, a short-circuit current density (Jsc) of 13.4 mA/cm2, a fill factor (FF) of 62%, and a power conversion efficiency (PCE) of 5.9% were demonstrated for BHJ PSCs based on the P-C10:PC71BM [1:3 (w/w)] blend film.Keywords: alkyl chain effect; conjugated polymers; film morphology; low band gap; polymer solar cells; power conversion efficiency;
Co-reporter:Jian-fei Qu;Jian Liu;Si-da Li;Zhi-yuan Xie
Chinese Journal of Polymer Science 2013 Volume 31( Issue 5) pp:815-822
Publication Date(Web):2013 May
DOI:10.1007/s10118-013-1276-x
Five novel donor-acceptor (D-A) conjugated cooligomers (F4B-hP, F5B-hP, F5B2[1,2]-hP, F5B2[1,3]-hP and F7B2[1,2]-hP) were synthesized. The absorption spectra of the cooligomers cover a wide range from 300 nm to 630 nm. The cooligomers could form films featured by alternating D-A lamellar nanostructures with the periods relative to the molecular lengths after thermal annealing or solvent vapor annealing. Single molecule solar cells were fabricated, and F5B-hP exhibited the best device performance. When the film of F5B-hP was thermally annealed, a power conversion efficiency (PCE) of 1.56% was realized. With solvent vapor annealing, the PCE could be further improved to 1.72% with a short-circuit current (JSC) of 5.76 mA/cm2, an open-circuit voltage (VOC) of 0.87 V and a fill factor (FF) of 0.34.
Co-reporter:Hongkun Tian, Yang Han, Cheng Bao, Donghang Yan, Yanhou Geng and Fosong Wang
Chemical Communications 2012 vol. 48(Issue 29) pp:3557-3559
Publication Date(Web):05 Mar 2012
DOI:10.1039/C2CC30407D
A novel thienoacene-based conjugated oligomer, i.e.BTTT-T-C12, was designed and synthesized. Its highly asymmetric structural feature enables the preparation of two-dimensional single-crystalline thin films in millimetre size and ∼100 nm thick by a solution processing method directly on the Si/SiO2 substrate. Single crystal organic thin film transistors exhibit a mobility of 0.70 cm2 V−1 s−1 and an on/off ratio of 5.7 × 104.
Co-reporter:Yagang Chen;Chengfang Liu;Hongkun Tian;Cheng Bao;Xiaojie Zhang;Donghang Yan;Fosong Wang
Macromolecular Rapid Communications 2012 Volume 33( Issue 20) pp:1759-1764
Publication Date(Web):
DOI:10.1002/marc.201200330
Abstract
Two conjugated polymers (CPs) P-tCzC12 and P-tCzC16 comprising alternating dithieno[3,2-b:6,7-b]carbazole and 4,4′-dihexadecyl-2,2′-bithiophene units have been designed and synthesized. Upon thermal annealing, they can form ordered thin films in which the polymer backbones dominantly adopted an edge-on orientation respective to the substrate with a lamellar spacing of ≈24 Å and a π-stacking distance of ≈3.7 Å. Organic thin-film transistors (OTFTs) were fabricated by solution casting. A hole mobility of 0.39 cm2 V−1s−1 has been demonstrated with P-tCzC16. This value is the highest among the CPs containing heteroacenes larger than 4 rings.
Co-reporter:Yagang Chen, Hao Chang, Hongkun Tian, Cheng Bao, Weili Li, Donghang Yan, Yanhou Geng, Fosong Wang
Organic Electronics 2012 Volume 13(Issue 12) pp:3268-3275
Publication Date(Web):December 2012
DOI:10.1016/j.orgel.2012.09.041
A novel easily made thienoacene-based organic semiconductor, i.e., dinaphtho[3,4-d:3′,4′-d′]benzo[1,2-b:4,5-b′]dithiophene (Ph5T2), was synthesized in high yield, and its thermal stability, electrochemical properties, thin-film morphology and field-effect mobility were investigated. Ph5T2 exhibit excellent thermal stability with a decomposition temperature (Td) of 427 °C. Thin-film X-ray diffraction (XRD) and atomic force microscopy (AFM) characterizations indicate that Ph5T2 can form highly ordered films with large domain size on the para-sexiphenyl (6P)-modified substrates. Organic thin-film transistors (OTFTs) with top-contact geometry based on Ph5T2 exhibit mobilities up to 1.2 cm2 V−1 s−1 in ambient. The devices are highly stable and exhibit almost no performance degradation during 3 months storage under ambient conditions with relative humidity up to 80%.Graphical abstractHighlights► High mobility: Ph5T2 is the first fused aromatic comprising seven fused rings which shows mobility beyond 1 cm2 V−1 s−1. ► Great device stability even in ambient with humidity up to 80%. ► Ease of mass preparation and unique chemical structure design.
Co-reporter:Yunfeng Deng, Yagang Chen, Xiaojie Zhang, Hongkun Tian, Cheng Bao, Donghang Yan, Yanhou Geng, and Fosong Wang
Macromolecules 2012 Volume 45(Issue 21) pp:8621-8627
Publication Date(Web):2017-2-22
DOI:10.1021/ma301864f
A series of donor–acceptor (D–A) conjugated polymers (CPs) comprising dithieno[2,3-b;7,6-b]carbazole (C1) or dithieno[3,2-b;6,7-b]carbazole (C2) as D unit and thienopyrroledione (TPD), isoindigo (IID), or diketopyrrolopyrrole (DPP) as A unit were synthesized, and their semiconducting properties were investigated with organic field-effect transistors (OFETs). Because of different bonding geometry of C1 and C2, the CPs based on these isomeric D units have distinct backbone conformation. The CPs based on C1 unit and all three A units show strong backbone curvature. In consequence, these polymers all formed amorphous films and exhibited low OFET mobility in the level of 10–3 cm2/(V s). P(TPD-C2) and P(DPP-C2), which comprise C2 and TPD or DPP, both display pseudo-straight-shaped backbones and formed ordered films with the polymer backbones adopting edge-on orientation respective to the substrates. Accordingly, P(TPD-C2) and P(DPP-C2) exhibited the highest mobility of 0.31 and 1.36 cm2/(V s), respectively. However, P(IID-C2) could only form amorphous films probably owing to its highly stiff backbone, leading to a moderate OFET mobility (2.96 × 10–2 cm2/(V s)). This implies that large fused aromatics are promising building blocks for high-mobility D–A CPs when polymer backbone conformation and rigidity are appropriately manipulated.
Co-reporter:Qilin Wang, Baohua Zhang, Lihui Liu, Yagang Chen, Yao Qu, Xiaojie Zhang, Junwei Yang, Zhiyuan Xie, Yanhou Geng, Lixiang Wang, and Fosong Wang
The Journal of Physical Chemistry C 2012 Volume 116(Issue 41) pp:21727-21733
Publication Date(Web):September 19, 2012
DOI:10.1021/jp3083369
Monodisperse hexadecyl(9,9-dioctylfluorene)s F16, BrF16, and BF16, which comprise H, Br, and boronic pinacol ester end groups, respectively, were synthesized, and the effect of these end groups on the photophysical, electrochemical, and electroluminescent properties of the polymers were investigated. The end groups have no noticeable effect on the energy levels of the polymers. F16 and BrF16 show high photoluminescence (PL) quantum yields (Φs) in both solution and film states. Film PL Φs (Φfilms) of F16 and BrF16 are 0.72 and 0.79, respectively. These values are about 1.4–1.5 times of that of BF16 and poly(9,9-dioctylfluorene) (PFO) prepared by Suzuki polycondensation. Moreover, Φfilms of F16 and BrF16 were kept almost the same after thermal annealing at 120 °C in both air and argon atmospheres. By contrast, the Φfilms of BF16 and PFO dramatically decreased to 0.25 and 0.29 after thermal annealing at 120 °C in air. Polymer light-emitting diodes (PLEDs) were fabricated. F16, BrF16, and PFO exhibited maximum luminance efficiencies of 0.60, 0.27, and 0.39 cd·A–1, respectively, while that of BF16 was as low as 0.024 cd·A–1. Meanwhile, green emission was observed for devices of BrF16, BF16, and PFO, but not for devices of F16. Electron- and hole-only devices were fabricated for elucidating the effect of end groups on charge transporting properties of the polymers. While Br is a mild hole-trapper, boronic ester group traps both holes and electrons, resulting in severely unbalanced hole- and electron-transport. Our results indicate that boronic ester end groups have a detrimental effect on the optoelectronic properties of polyfluorenes larger than Br.
Co-reporter:Bo He, Hongkun Tian, Donghang Yan, Yanhou Geng and Fosong Wang
Journal of Materials Chemistry A 2011 vol. 21(Issue 38) pp:14793-14799
Publication Date(Web):18 Aug 2011
DOI:10.1039/C1JM13086B
Three thiophene/phenanthrene hybrid oligomers were synthesized and their liquid crystalline (LC) properties were characterized by differential scanning calorimetry (DSC), polarized optical microscopy (POM), temperature-dependent X-ray diffraction (XRD) and electron diffraction. Highly ordered LC phases with a broad temperature range were observed for all three oligomers probably owing to the absence of symmetry against the long axis of phenanthrene unit. Highly ordered smectic LC thin films were prepared by vacuum deposition and their organic thin film transistors (OTFTs) exhibited high mobilities up to 0.34 cm2 V−1s−1. Solution processed films showed self-healing behaviors upon thermal annealing, and OTFTs prepared by solution drop casting showed mobilities up to 0.05 cm2 V−1s−1. These results indicate that thiophene/phenanthrene hybrid oligomers are promising high mobility organic semiconductors for OTFTs.
Co-reporter:Jinming Hu, Guoying Zhang, Yanhou Geng, and Shiyong Liu
Macromolecules 2011 Volume 44(Issue 20) pp:8207-8214
Publication Date(Web):September 19, 2011
DOI:10.1021/ma201777p
We report on the fabrication of a novel type of ratiometric fluorescent polymeric probes for fluoride ions (F–) based on self-assembled micellar nanoparticles of P(MMA-co-NBDAE)-b-PF-b-P(MMA-co-NBDAE) coil–rod–coil triblock copolymer, where MMA, NBDAE, and PF are methyl methacrylate, 4-(2-acryloyloxyethylamino)-7-nitro-2,1,3-benzoxadiazole, and polyfluorene, respectively. Blue-emitting conjugated PF block and green-emitting NBDAE moieties with F– turn-off characteristics within the PMMA block serve as fluorescence resonance energy transfer (FRET) donors and switchable acceptors, respectively. For coil–rod–coil triblock copolymer in a good solvent such as THF, the blue emission of PF block dominates due to unimolecularly dissolved state associated with ineffective FRET process. The addition of F– ions only leads to ∼2.92-fold decrease of fluorescence intensity ratio, I515/I417, of characteristic NBDAE and PF emission bands. In acetone, the triblock copolymer spontaneously self-assembles into micelles possessing PF cores and NBDAE-labeled PMMA coronas. In the absence of F– ions, effective FRET processes between micellar cores and coronas occurs, resulting in prominently enhanced NBDAE emission. Upon addition of F– ions, the quenching of NBDAE emission bands leads to ∼8.75-fold decrease in the emission intensity ratio, I515/I417, which is also accompanied by naked eye-discernible fluorometric transition from cyan to blue emissions and colorimetric transition from green to yellowish. At a micellar concentration of 0.1 g/L in acetone at 25 °C, the detection limit of F– ions can be down to ∼4.78 μM (∼0.09 ppm). This work presents a new example of polymeric micelles-based optical F– probes and manifests that, upon proper structural design and optimization of spatial distribution of FRET donors and acceptors, self-assembled micelles of coil–rod–coil triblock copolymers serve as better ratiometric fluorescent F– ion sensors possessing visual detection capability, as compared to that of molecularly dissolved chains.
Co-reporter:Shupeng Wu, Li Huang, Hongkun Tian, Yanhou Geng, and Fosong Wang
Macromolecules 2011 Volume 44(Issue 19) pp:7558-7567
Publication Date(Web):September 6, 2011
DOI:10.1021/ma201192p
The effect of LiCl on the chain growth Kumada catalyst-transfer polycondensation (KCTP) of the “reversed” thiophene monomer, 5-bromo-2-chloromagnesio-3-hexylthiophene (3a) (that has bulky substituent adjacent to the chloromagnesium group), was investigated. LiCl promotes the polymerization of 3a, and the polymerization also exhibits living characteristics similar to those of the “normal” monomer, 2-bromo-5-chloromagnesio-3-hexylthiophene (3b). However, initiation is much slower than chain propagation due to the steric hindrance between hexyl groups in the transmetalation (TM) step that leads to the formation of the initiator via head-to-head (HH) coupling. Consequently, regioregular poly(3-hexylthiophene) (P3HT) with large polydispersity (PDI) and higher number-average molecular weight (Mn) than the theoretical value was obtained. Because of the slow initiation with 3a, the polymerization of 3a occurs primarily after the consumption of 3b in the copolymerization of 3a and 3b, and P3HT with high regioregularity was still obtained.
Co-reporter:Yagang Chen, Hongkun Tian, Donghang Yan, Yanhou Geng, and Fosong Wang
Macromolecules 2011 Volume 44(Issue 13) pp:5178-5185
Publication Date(Web):June 15, 2011
DOI:10.1021/ma2007249
Three alternating conjugated polymers (P-bTC10, P-bTC12, and P-bTC16) comprising a novel S- and N-containing heteroarene, i.e., N-dodecyldithieno[2,3-b;7,6-b]carbazole, and 4,4′-dialkyl-2,2′-bithiophenes have been designed and synthesized. The nitrogen atom in the heteroarene allows introducing an additional alkyl substituent in each repeating unit of the polymers. The resulting polymers are thermally stable with decomposition temperature of ∼400 °C and highly soluble in various organic solvents, such as tetrahydrofuran (THF), toluene, chloroform, and chlorobenzene, etc. Bottom gate, top contact OTFT devices were fabricated by solution casting. Mobility of the devices increased with an increase of the alkyl chain length in bithiophene units, and P-bTC10, P-bTC12, and P-bTC16 exhibited the mobilities up to 0.0064, 0.022, and 0.035 cm2/(V s), respectively. The mobility of P-bTC16 is comparable to that of regioregular poly(3-hexylthiophene) (rr-P3HT) reference devices, indicating that this heteroarene is a potential building block for high-mobility conjugated polymers.
Co-reporter:Qilin Wang, Yao Qu, Hongkun Tian, Yanhou Geng, and Fosong Wang
Macromolecules 2011 Volume 44(Issue 6) pp:1256-1260
Publication Date(Web):February 14, 2011
DOI:10.1021/ma102954h
Co-reporter:Laju Bu, Xiaoyang Guo, Bo Yu, Yingying Fu, Yao Qu, Zhiyuan Xie, Donghang Yan, Yanhou Geng, Fosong Wang
Polymer 2011 Volume 52(Issue 19) pp:4253-4260
Publication Date(Web):1 September 2011
DOI:10.1016/j.polymer.2011.07.029
A series of novel donor–acceptor (D–A) liquid crystalline conjugated cooligomers, i.e. F3T4-epP, F4T6-epP and F5T8-epP, which comprise oligo(fluorene-alt-bithiophene)s (OFbTs) with the different lengths as the donor segments and a perylene diimide (PDI) derivative as the acceptor segment, were designed and synthesized. The cooligomers can form the films with the desired ideal morphology for bulk heterojunction (BHJ) polymer solar cells (PSCs). That means the films comprise ordered alternating D–A lamellae perpendicular to the substrates. Most importantly, the periods of the nanostructures can be tuned by varying molecular length and post-treatment condition. For F3T4-epP and F4T6-epP, the periods are close to the single and double molecular lengths upon thermal and solvent vapor annealing, respectively. However, only the nanostructures with the period close to the single molecular length were formed for F5T8-epP for both annealing processes. Solar cells based on above nanostructured films were fabricated to demonstrate the advantages of the ideal morphology for BHJ solar cells. It was found that the power conversion efficiency (PCE) of the devices was dependent on the molecular length and the order of the films. Solvent vapor annealed films exhibited the highest order therefore gave the best device performance. A PCE of 1.75% was demonstrated with the solvent vapor annealed films of F5T8-epP. This performance represents the best among the solar cells based on the single molecular materials.
Co-reporter:Hongkun Tian, Yunfeng Deng, Feng Pan, Lizhen Huang, Donghang Yan, Yanhou Geng and Fosong Wang
Journal of Materials Chemistry A 2010 vol. 20(Issue 37) pp:7998-8004
Publication Date(Web):16 Aug 2010
DOI:10.1039/C0JM01173H
Two ladder-type conjugated molecules, i.e., 2,2′-(2,7-dihexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-4,9-diylidene) dimalononitrile (1) and 2,7-dihexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-4,9-dione (2) were synthesized in high yields, and their electrochemical properties, single crystal structures, thin-film morphology and field-effect mobility were investigated. The LUMO/HOMO levels of 1 and 2 are −4.07/−6.00 and −3.62/−5.82 eV, respectively, as estimated from the thin-film cyclic voltammetry measurements. In the single crystals, both compounds exhibit one dimensional π–π stacking of molecules, and 1 shows the larger π-electron overlap between the neighboring molecules than 2, along with interdigitation of alkyl chains. Thin-film X-ray diffraction (XRD) and atomic force microscopy (AFM) characterizations indicate that 1 can form films with higher molecular order than 2. Field-effect electron mobility up to 0.33 cm2 V−1 s−1 in air for 1 and hole mobility up to 0.05 cm2 V−1 s−1 for 2 have been demonstrated with the top-contact organic thin-film transistor (OTFT) device structure. Electron mobility of 1 is among the highest value for n-type organic semiconductors.
Co-reporter:Huiyu Zhao, Xiaoyang Guo, Hongkun Tian, Changyin Li, Zhiyuan Xie, Yanhou Geng and Fosong Wang
Journal of Materials Chemistry A 2010 vol. 20(Issue 15) pp:3092-3097
Publication Date(Web):01 Mar 2010
DOI:10.1039/B925089A
[6,6]-Thienyl-C61-butyric acid ester derivatives with methyl, hexyl and 2-ethylhexyl at the 5-position of thiophene ring (TCBM-Cn, n represents the number of carbon atom in the alkyl chain) were synthesized. Unlike [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), these methanofullerene derivatives ([6,6] adduct) can be directly obtained from the typical diazo addition under mild conditions, and high temperature isomerization is unnecessary. With a hexyl or 2-ethylhexyl group at the 5-position of thiophene, the solubility of TCBM-Cn in chlorobenzene is as high as 180 ± 10 mg ml−1. Bulk heterojunction photovoltaic solar cells were fabricated with a device structure of ITO/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/poly(3-hexylthiophene) (P3HT):TCBM-Cn (1:0.8 w/w)/LiF/Al. The device based-on TCBM-C6 exhibited the best performance with a power conversion efficiency (PCE) of up to 4.26%.
Co-reporter:Shupeng Wu, Yuequan Sun, Li Huang, Jianwei Wang, Yihan Zhou, Yanhou Geng and Fosong Wang
Macromolecules 2010 Volume 43(Issue 10) pp:4438-4440
Publication Date(Web):April 22, 2010
DOI:10.1021/ma100537d
Co-reporter:YanHou Geng;Li Huang;ShuPeng Wu;FoSong Wang
Science China Chemistry 2010 Volume 53( Issue 8) pp:1620-1633
Publication Date(Web):2010 August
DOI:10.1007/s11426-010-4048-2
Kumada chain-growth polycondensation (KCGP) is a novel method for the synthesis of well-defined conjugated polymers. Because the Ni-catalyst can transfer in an intramolecular process to the propagating chain end, the polymerization follows chain-growth mechanism. With this newly developed method, various conjugated polymers, such as polythiophenes, poly(p-phenylene) (PPP), polypyrrole (PPy), and polyfluorene with controlled molecular weights and relatively narrow polydispersities (PDIs), have been prepared. Especially, the polymerizations for poly(3-alkylthiophene)s (P3ATs), PPP, and PPy exhibited quasi-living characteristics, which allows preparing polymer brushes, fully-conjugated block copolymers, and macroinitiators and macro-reactants for the synthesis of rod-coil block copolymers. In the current review, the progress in this new area is summarized.
Co-reporter:Laju Bu ; Xiaoyang Guo ; Bo Yu ; Yao Qu ; Zhiyuan Xie ; Donghang Yan ; Yanhou Geng ;Fosong Wang
Journal of the American Chemical Society 2009 Volume 131(Issue 37) pp:13242-13243
Publication Date(Web):September 1, 2009
DOI:10.1021/ja905980w
A series of donor−acceptor (D−A) co-oligomers with oligo(fluorene-alt-bithiophene) and perylene diimide as donor and acceptor segments, respectively, have been designed and synthesized. They can self-assembly into alternating D−A lamellar nanostructured films with the periods depending on the molecular length. These films have been successfully used in fabrication of high-performance single-molecular solar cells with power conversion efficiency up to 1.50%.
Co-reporter:Xiaojie Zhang, Laju Bu, Yao Qu, Lixiang Wang, Yanhou Geng and Fosong Wang
Journal of Materials Chemistry A 2009 vol. 19(Issue 3) pp:399-408
Publication Date(Web):05 Dec 2008
DOI:10.1039/B811830B
3′-Nonafluorobutylmethyl-4′-methyl-spiro[cyclopentyl-9,1′]fluorenes were successfully synthesized via tandem radical-addition reactions between 9,9-diallylfluorenes and perfluorobutyl iodide in the presence of a radical initiator followed by reduction under mild conditions. Single crystal analysis indicates that two substituents at 3,4-positions of cyclopentane are in a maleinoid form. Accordingly, four oligo(fluorene-co-bithiophene)s with the same molecular length of ∼10 nm (7 fluorene units and 12 thiophene units) containing one to three novel spiro-fluorene units were synthesized. The introduction of the spiro-fluorene units results in noticeable enhancement of both glass transition temperature (Tg) and clearing point temperature (Tc) of the oligomers, but has little effect on their photophysical properties. Exchanging three 9,9-dioctylfluorene units with 3′-nonafluorobutylmethyl-4′-methyl-spiro[cyclopentyl-9,1′] fluorene units results in a 37 °C enhancement of Tg and a 61 °C enhancement of Tc. All these results indicate that this new spiro-fluorene unit is an attractive building block for liquid crystalline conjugated polymers/oligomers with both high Tg and Tc.
Co-reporter:Wei Yue, Yun Zhao, Shuyan Shao, Hongkun Tian, Zhiyuan Xie, Yanhou Geng and Fosong Wang
Journal of Materials Chemistry A 2009 vol. 19(Issue 15) pp:2199-2206
Publication Date(Web):12 Feb 2009
DOI:10.1039/B818885H
Three low bandgap conjugated polymers, i.e., PDTPBT-C8, PDTPBT-C6 and PDTPBT-C5, which consist of alternating N-alkyl dithieno[3,2-b:2′,3′-d]pyrrole and 2,1,3-benzothiadiazole units and carry 1-octylnonyl, 1-hexylheptyl and 1-pentylhexyl as side chains, respectively, were synthesized. These polymers show strong absorption in the wavelength range of 600–900 nm with enhanced absorption coefficient as the length of alkyl chain decreases. The film morphology of the polymers and 1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-C-61 (PCBM) blends is also dependent on the alkyl chain length. As the length decreases, the film becomes more uniform and the domian size decreases from 400–900 nm for PDTPBT-C8 to ∼50 nm for PDTPBT-C5. Bulk heterojunction photovoltaic solar cells (PSCs) were fabricated based on the blend of the polymers and PCBM with a weight ratio of 1:3. The device performance is dramatically improved as the length of the side chain decreases, due to enhanced film absorption coefficient and improved film morphology. With the polymer PDTPBT-C5, which carries the shortest alkyl chain, power conversion efficiency (PCE) up to 2.80% has been achieved. This result indicates that optimizing the structure of the solublizing alkyl chain is also crucial for the design and synthesis of high performance PSC polymeric materials.
Co-reporter:Shaoqiang Dong, Hongkun Tian, De Song, Zhenhua Yang, Donghang Yan, Yanhou Geng and Fosong Wang
Chemical Communications 2009 (Issue 21) pp:3086-3088
Publication Date(Web):14 Apr 2009
DOI:10.1039/B822819A
Tetraoctyl-substituted vanadyl phthalocyanine (OVPc4C8) as a new NIR-absorbing discotic liquid crystalline material can form highly ordered thin films with edge-on alignment of the molecules and molecular packing mode identical to that in the phase II of OVPc for solution processed OTFTs with mobility up to 0.017 cm2 V−1 s−1.
Co-reporter:Shupeng Wu, Laju Bu, Li Huang, Xinhong Yu, Yanchun Han, Yanhou Geng, Fosong Wang
Polymer 2009 50(26) pp: 6245-6251
Publication Date(Web):
DOI:10.1016/j.polymer.2009.11.001
Co-reporter:Weibin Cui, Yun Zhao, Hongkun Tian, Zhiyuan Xie, Yanhou Geng and Fosong Wang
Macromolecules 2009 Volume 42(Issue 21) pp:8021-8027
Publication Date(Web):August 31, 2009
DOI:10.1021/ma901514q
A poly(9,10-bisalkynyl-2,6-anthrylene) (P1) and five poly(9,10-bisarylethynyl-2,6-anthrylene)s (P2−P6) as soluble conjugated polymers have been synthesized and characterized. All polymers exhibit two-dimensional conjugated characteristics as indicated by absorption spectra comprising multibands in the range of 300−600 nm. Compared with P1, polymers P2−P5, which contain phenylethynyl substituents with the longer conjugation than alkynyl groups, exhibit a ∼60 nm red shift of absorption edge. However, further increasing the conjugation length of the arylethynyl substituents (longer than phenylethynyl) has only a negligible effect on the conjugation of the polymer chains, while comparing the absorption spectra of P6 with those of P2−P5. All polymers show absorption spectra with a noticeable red shift from solutions to films, indicative of stronger intermolecular interaction in solid state. The highest occupied molecular orbital (HOMO) energy levels are −5.32 eV for P1 and around −5.20 eV for phenylethynyl-substituted polymers. Bulk heterojunction polymer solar cells (PSCs) of the polymers were fabricated with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) as the acceptor material. Polymer P1 exhibits the highest power conversion efficiency (PCE) of 1.60% with an open-circuit voltage (Voc) of 0.96 V, a short-circuit current density (Jsc) of 3.18 mA/cm2, and a fill factor (FF) of 0.53.
Co-reporter:Laju Bu, Yao Qu, Donghang Yan, Yanhou Geng and Fosong Wang
Macromolecules 2009 Volume 42(Issue 5) pp:1580-1588
Publication Date(Web):February 9, 2009
DOI:10.1021/ma802601c
A series of coil−rod−coil triblock copolymers (i.e., F3T8EO8, F3T8EO17, F3T8EO45, and F3T8EO125) with a mesogenic monodisperse conjugated oligomer comprising 3 fluorene, 8 thiophene, and 2 phenyl units as the rod and poly(ethylene oxide) (PEO) as the coil were synthesized. A reference compound, that is F3T8ME2, with the identical rod but without PEO was also prepared for comparison. The volume fraction of PEO (fPEO) was 0, 0.16, 0.28, 0.50, and 0.73 for F3T8ME2, F3T8EO8, F3T8EO17, F3T8EO45, and F3T8EO125, respectively. It was found that the introduction of PEO into the triblock copolymers encouraged the formation of H-type aggregation and fPEO-dependent highly ordered mesophases while fPEO < 0.73. For F3T8ME2, only nematic mesophase was observed. In contrast, F3T8EO8 and F3T8EO17, with fPEO of 0.16 and 0.28, respectively, are smectic A (SA) mesomorphism. For F3T8EO45 with fPEO of 0.50, several highly ordered phases, such as hexagonal columnar crystalline phase and rectangular columnar, smectic B (SB) and SA mesophases, appear in succession upon heating. However, large fPEO suppresses the formation of mesophase. For F3T8EO125 with fPEO = 0.73, only a crystalline phase was observed. Meanwhile, thin films of above triblock copolymers exhibit lamellar or cylindrical nanostructures consistent with the phase structures at room temperatures, which render the block copolymers different spectroscopic properties. These results indicate that it is possible to control the supramolecular nanostructures of conjugated materials and then to tune their optoelectronic properties by designing rod−coil block copolymers with appropriate chemical structures.
Co-reporter:Wei Yue, Yun Zhao, Hongkun Tian, De Song, Zhiyuan Xie, Donghang Yan, Yanhou Geng and Fosong Wang
Macromolecules 2009 Volume 42(Issue 17) pp:6510-6518
Publication Date(Web):July 20, 2009
DOI:10.1021/ma900906t
A series of donor−acceptor low-bandgap conjugated polymers, i.e., PTnBT (n = 2−6), composed of alternating oligothiophene (OTh) and 2,1,3-benzothiadiazole (BT) units were synthesized by Stille cross-coupling polymerization. The number of thiophene rings in OTh units, that is n, was tuned from 2 to 6. All these polymers display two absorption bands in both solutions and films with absorption maxima depending on n. From solution to film, absorption spectra of the polymers exhibit a noticeable red shift. Both high- and low-energy absorption bands of PT5BT and PT6BT films locate in the visible region, which are at 468 and 662 nm for PT5BT and 494 and 657 nm for PT6BT. Consequently, their absorption spectra cover the region between 400 and 800 nm, and their optical bandgaps are 1.56 and 1.52 eV, respectively, which renders them “black” polymers. Moreover, PT5BT and PT6BT can form highly ordered thin films with field-effect mobilities up to 2.46 × 10−2 and 1.40 × 10−2 cm2 V−1 s−1, respectively. Bulk-heterojunction polymer solar cells (PSCs) fabricated with these polymers as the donor materials and 1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-C-61 (PCBM) as the acceptor material exhibited power conversion efficiencies (PCEs) of 0.93−2.23%. PSCs based on the high-mobility “black” polymer PT6BT showed the best device performance with a PCE of 2.23%. Our results provide a rational strategy for design and synthesis of high-mobility low-bandgap conjugated polymers with broad absorption range.
Co-reporter:Weibin Cui, Yubo Wu, Hongkun Tian, Yanhou Geng and Fosong Wang
Chemical Communications 2008 (Issue 8) pp:1017-1019
Publication Date(Web):18 Dec 2007
DOI:10.1039/B713463K
The first soluble conjugated poly(2,6-anthrylene) with 9,10-diphenyl-anthracene as the repeating unit is reported; photophysical studies reveal that this polymer represents a novel well-conjugated system.
Co-reporter:Wei Yue, HongKun Tian, Ninghai Hu, Yanhou Geng and Fosong Wang
Crystal Growth & Design 2008 Volume 8(Issue 7) pp:2352-2358
Publication Date(Web):June 7, 2008
DOI:10.1021/cg701148z
Oligothiophenes (OThs) end-capped with 3-quinolyl or pyridyl with nitrogen atom at meta-, ortho- or para-position were synthesized. The single-crystal structures of the resulting molecules, i.e., o-PyTh4, m-PyTh4, p-PyTh4, QuTh2, and QuTh3, were successfully determined by single-crystal X-ray analysis. Pyridyl end-capped OThs, o-PyTh4, m-PyTh4, and p-PyTh4, adopt the different herringbone packing arrangement in crystals depending on the position of the nitrogen atom because of the presence of weak C−H···N hydrogen bonds. The p-PyTh4 molecules are linked each other along the long axis of the molecules to form the extended chains by C−H···N dimer synthon. For m-PyTh4, the C−H···N interactions two-dimensionally extend through C−H···N trimer synthon. The weak hydrogen-bonding network is much more complex in o-PyTh4 crystals because o-PyTh4 has two crystallographically independent molecules. Two-dimensional (2D) hydrogen-bonding networks arranging along the direction of diagonals in the ab plane are formed by the C−H···N trimer synthon. The crystal packing motifs of 3-quinolyl end-capped OThs are distinctly different from pyridyl end-capped ones. The QuTh2 molecules form a 2D face to face π−π slip stacking driven by the interaction of donor and acceptor segments between the neighboring molecules. For QuTh3, the weak C−H···N hydrogen bonds between the two molecules in the same layer and the CH/π weak interactions together force the molecules to form a sandwich-herringbone crystal packing motif. These results provide a new protocol to control molecular packing arrangement of conjugated oligomers.
Co-reporter:Li Huang, Shupeng Wu, Yao Qu, Yanhou Geng and Fosong Wang
Macromolecules 2008 Volume 41(Issue 22) pp:8944-8947
Publication Date(Web):October 30, 2008
DOI:10.1021/ma801538q
Co-reporter:Qin Liu, Yao Qu, Yanhou Geng and Fosong Wang
Macromolecules 2008 Volume 41(Issue 16) pp:5964-5966
Publication Date(Web):July 22, 2008
DOI:10.1021/ma801172k
Co-reporter:H. K. Tian;J. W. Shi;B. He;N. H. Hu;S. Q. Dong;D. H. Yan;J. P. Zhang;Y. H. Geng;F. S. Wang
Advanced Functional Materials 2007 Volume 17(Issue 12) pp:
Publication Date(Web):6 JUL 2007
DOI:10.1002/adfm.200706198
Two series of oligothiophenes (OThs), NaTn and TNTn (n = 2–6 represents the number of thiophene rings), end-capped with naphthyl and thionaphthyl units have been synthesized by means of Stille coupling. Their thermal properties, optical properties, single crystal structures, and organic field-effect transistor performance have been characterized. All oligomers display great thermal stability and crystallinity. The crystallographic structures of NaT2, NaT3, TNT2, and TNT3 have been determined. The crystals of NaT2 and NaT3 are monoclinic with space group P21/C, while those of TNT2 and TNT3 are triclinic and orthorhombic with space groups P and P212121, respectively. All oligomers adopt the well-known herringbone packing-mode in crystals with packing parameters dependent on the structure of the end-capping units and the number of thiophene rings. The shorter intermolecular distance in NaT3 compared to NaT2 indicates that the intermolecular interaction principally increases with increasing molecular length. X-ray diffraction and atomic force microscopy (AFM) characterization indicate that the NaTn oligomers can form films with better morphology and high molecular order than TNTn oligomers with the same number of thiophene rings. The NaTn oligomers exhibit mobilities that are much higher than those for TNTn oligomers (0.028–0.39 cm2 V–1 s–1 versus 0.010–0.055 cm2 V–1 s–1, respectively). In particular, the NaTn oligomers with n = 4–6 all show a mobility higher than 0.1 cm2 V–1 s–1. This device performance is among the best in aryl end-capped OThs, and indicates that naphthyl is an effectual building block for designing high-performance organic semiconducting materials.
Co-reporter:Xiaojie Zhang;Yao Qu;Laju Bu;Hongkun Tian Dr.;Jingping Zhang ;Lixiang Wang ;Fosong Wang
Chemistry - A European Journal 2007 Volume 13(Issue 21) pp:
Publication Date(Web):25 APR 2007
DOI:10.1002/chem.200700007
A series of monodisperse oligo(9,9-di-n-octylfluorene-co-bithiophene)s (OFbTs) with molecular lengths of up to 19.5 nm and molecular weights up to 7025 g mol−1 has been synthesized by a divergent/convergent approach involving Stille coupling reactions. Stille coupling is quite efficient in preparing this class of oligomers, and even the molecule with nine fluorene units and eight bithiophene units (F9Th16) can be synthesized in a yield as high as 70 %. Because of easy functionalization of the thiophene ring at its α position, no additional protecting group allowing activation for further reaction is necessary. However, the synthetic routes must be optimized to eliminate contamination of the targeting compounds with the homocoupling product of the organotin reagents. Synthesis of the longest oligomer F13Th24 in a relative large quantity is limited by its low yield due to the pronounced ligand-exchange side reactions of the starting materials and reaction intermediates. All oligomers longer than F4Th6 are nematic mesomorphs and exhibit enhanced glass transition temperature and clearing point with increasing molecular length, as revealed by differential scanning calorimetry and polarizing optical microscopy. Absorption and photoluminescence (PL) measurements reveal that OFbTs are well-conjugated systems with an effective conjugation length longer than the length of F13Th24.
Co-reporter:H. K. Tian;Y. H. Geng;D. H. Yan;J. W. Shi;L. X. Wang;F. S. Wang
Advanced Materials 2006 Volume 18(Issue 16) pp:2149-2152
Publication Date(Web):25 JUL 2006
DOI:10.1002/adma.200600178
An organic semiconductor that can be mass produced is synthesized by end-capping quaterthiophene with naphthyl units (NaT4). An organic thin-film transistor (OTFT, see figure) has been fabricated using this organic semiconductor, and exhibits stability under ambient conditions with a mobility of up to 0.40 cm2 V–1 s–1.
Co-reporter:Hongkun Tian, Jianwu Shi, Shaoqiang Dong, Donghang Yan, Lixiang Wang, Yanhou Geng and Fosong Wang
Chemical Communications 2006 (Issue 33) pp:3498-3500
Publication Date(Web):13 Jul 2006
DOI:10.1039/B606759J
Two novel phenanthrene-based conjugated oligomers were synthesized and used as p-channel semiconductors in field-effect transistors; they exhibit high mobility and excellent stability during long-time ambient storage and under UV irradiation.
Co-reporter:Hongkun Tian, Jun Wang, Jianwu Shi, Donghang Yan, Lixiang Wang, Yanhou Geng and Fosong Wang
Journal of Materials Chemistry A 2005 vol. 15(Issue 29) pp:3026-3033
Publication Date(Web):13 Jun 2005
DOI:10.1039/B504044B
A series of thiophene-aryl co-oligomers with phenyl-based central units, i.e. phenyl, biphenyl, fluorene and phenanthrene, were synthesized, and their optical properties and charge carrier transporting properties were characterized. The co-oligomers with biphenyl and phenanthrene units exhibited significantly improved thermal stability. Absorption measurements and electrochemical characterization revealed that all co-oligomers have broader band gap and lower HOMO levels than the corresponding thiophene oligomer, α,ω-dihexylsexithiophene (DHα6T). Introduction of biphenyl and phenanthrene units afforded co-oligomers with the broadest band gap and lowest HOMO levels in comparison with the counterparts of phenyl and fluorene central units. Depending on the structure of the central units, the field-effect mobility (μTFT) of the co-oligomers from top-contact thin film transistors is in the range of (1–6.7)
× 10−2 cm2 V−1 s−1. The rigid and planar central unit is favorable for good device performance. Among the co-oligomers, 2,7-bis(5′-hexyl-2,2′-bithien-5-yl)phenanthrene (DH-TTPhTT) exhibits the highest μTFT of 6.7 × 10−2 cm2 V−1 s−1, comparable to that of DHα6T in the same device configuration and fabrication conditions.
Co-reporter:Wei Yue, Yun Zhao, Shuyan Shao, Hongkun Tian, Zhiyuan Xie, Yanhou Geng and Fosong Wang
Journal of Materials Chemistry A 2009 - vol. 19(Issue 15) pp:NaN2206-2206
Publication Date(Web):2009/02/12
DOI:10.1039/B818885H
Three low bandgap conjugated polymers, i.e., PDTPBT-C8, PDTPBT-C6 and PDTPBT-C5, which consist of alternating N-alkyl dithieno[3,2-b:2′,3′-d]pyrrole and 2,1,3-benzothiadiazole units and carry 1-octylnonyl, 1-hexylheptyl and 1-pentylhexyl as side chains, respectively, were synthesized. These polymers show strong absorption in the wavelength range of 600–900 nm with enhanced absorption coefficient as the length of alkyl chain decreases. The film morphology of the polymers and 1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-C-61 (PCBM) blends is also dependent on the alkyl chain length. As the length decreases, the film becomes more uniform and the domian size decreases from 400–900 nm for PDTPBT-C8 to ∼50 nm for PDTPBT-C5. Bulk heterojunction photovoltaic solar cells (PSCs) were fabricated based on the blend of the polymers and PCBM with a weight ratio of 1:3. The device performance is dramatically improved as the length of the side chain decreases, due to enhanced film absorption coefficient and improved film morphology. With the polymer PDTPBT-C5, which carries the shortest alkyl chain, power conversion efficiency (PCE) up to 2.80% has been achieved. This result indicates that optimizing the structure of the solublizing alkyl chain is also crucial for the design and synthesis of high performance PSC polymeric materials.
Co-reporter:Xiaojie Zhang, Laju Bu, Yao Qu, Lixiang Wang, Yanhou Geng and Fosong Wang
Journal of Materials Chemistry A 2009 - vol. 19(Issue 3) pp:NaN408-408
Publication Date(Web):2008/12/05
DOI:10.1039/B811830B
3′-Nonafluorobutylmethyl-4′-methyl-spiro[cyclopentyl-9,1′]fluorenes were successfully synthesized via tandem radical-addition reactions between 9,9-diallylfluorenes and perfluorobutyl iodide in the presence of a radical initiator followed by reduction under mild conditions. Single crystal analysis indicates that two substituents at 3,4-positions of cyclopentane are in a maleinoid form. Accordingly, four oligo(fluorene-co-bithiophene)s with the same molecular length of ∼10 nm (7 fluorene units and 12 thiophene units) containing one to three novel spiro-fluorene units were synthesized. The introduction of the spiro-fluorene units results in noticeable enhancement of both glass transition temperature (Tg) and clearing point temperature (Tc) of the oligomers, but has little effect on their photophysical properties. Exchanging three 9,9-dioctylfluorene units with 3′-nonafluorobutylmethyl-4′-methyl-spiro[cyclopentyl-9,1′] fluorene units results in a 37 °C enhancement of Tg and a 61 °C enhancement of Tc. All these results indicate that this new spiro-fluorene unit is an attractive building block for liquid crystalline conjugated polymers/oligomers with both high Tg and Tc.
Co-reporter:Hongkun Tian, Yang Han, Cheng Bao, Donghang Yan, Yanhou Geng and Fosong Wang
Chemical Communications 2012 - vol. 48(Issue 29) pp:NaN3559-3559
Publication Date(Web):2012/03/05
DOI:10.1039/C2CC30407D
A novel thienoacene-based conjugated oligomer, i.e.BTTT-T-C12, was designed and synthesized. Its highly asymmetric structural feature enables the preparation of two-dimensional single-crystalline thin films in millimetre size and ∼100 nm thick by a solution processing method directly on the Si/SiO2 substrate. Single crystal organic thin film transistors exhibit a mobility of 0.70 cm2 V−1 s−1 and an on/off ratio of 5.7 × 104.
Co-reporter:Weibin Cui, Yubo Wu, Hongkun Tian, Yanhou Geng and Fosong Wang
Chemical Communications 2008(Issue 8) pp:NaN1019-1019
Publication Date(Web):2007/12/18
DOI:10.1039/B713463K
The first soluble conjugated poly(2,6-anthrylene) with 9,10-diphenyl-anthracene as the repeating unit is reported; photophysical studies reveal that this polymer represents a novel well-conjugated system.
Co-reporter:Bo He, Hongkun Tian, Donghang Yan, Yanhou Geng and Fosong Wang
Journal of Materials Chemistry A 2011 - vol. 21(Issue 38) pp:NaN14799-14799
Publication Date(Web):2011/08/18
DOI:10.1039/C1JM13086B
Three thiophene/phenanthrene hybrid oligomers were synthesized and their liquid crystalline (LC) properties were characterized by differential scanning calorimetry (DSC), polarized optical microscopy (POM), temperature-dependent X-ray diffraction (XRD) and electron diffraction. Highly ordered LC phases with a broad temperature range were observed for all three oligomers probably owing to the absence of symmetry against the long axis of phenanthrene unit. Highly ordered smectic LC thin films were prepared by vacuum deposition and their organic thin film transistors (OTFTs) exhibited high mobilities up to 0.34 cm2 V−1s−1. Solution processed films showed self-healing behaviors upon thermal annealing, and OTFTs prepared by solution drop casting showed mobilities up to 0.05 cm2 V−1s−1. These results indicate that thiophene/phenanthrene hybrid oligomers are promising high mobility organic semiconductors for OTFTs.
Co-reporter:Huiyu Zhao, Xiaoyang Guo, Hongkun Tian, Changyin Li, Zhiyuan Xie, Yanhou Geng and Fosong Wang
Journal of Materials Chemistry A 2010 - vol. 20(Issue 15) pp:NaN3097-3097
Publication Date(Web):2010/03/01
DOI:10.1039/B925089A
[6,6]-Thienyl-C61-butyric acid ester derivatives with methyl, hexyl and 2-ethylhexyl at the 5-position of thiophene ring (TCBM-Cn, n represents the number of carbon atom in the alkyl chain) were synthesized. Unlike [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), these methanofullerene derivatives ([6,6] adduct) can be directly obtained from the typical diazo addition under mild conditions, and high temperature isomerization is unnecessary. With a hexyl or 2-ethylhexyl group at the 5-position of thiophene, the solubility of TCBM-Cn in chlorobenzene is as high as 180 ± 10 mg ml−1. Bulk heterojunction photovoltaic solar cells were fabricated with a device structure of ITO/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/poly(3-hexylthiophene) (P3HT):TCBM-Cn (1:0.8 w/w)/LiF/Al. The device based-on TCBM-C6 exhibited the best performance with a power conversion efficiency (PCE) of up to 4.26%.
Co-reporter:Hongkun Tian, Yunfeng Deng, Feng Pan, Lizhen Huang, Donghang Yan, Yanhou Geng and Fosong Wang
Journal of Materials Chemistry A 2010 - vol. 20(Issue 37) pp:NaN8004-8004
Publication Date(Web):2010/08/16
DOI:10.1039/C0JM01173H
Two ladder-type conjugated molecules, i.e., 2,2′-(2,7-dihexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-4,9-diylidene) dimalononitrile (1) and 2,7-dihexyl-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-4,9-dione (2) were synthesized in high yields, and their electrochemical properties, single crystal structures, thin-film morphology and field-effect mobility were investigated. The LUMO/HOMO levels of 1 and 2 are −4.07/−6.00 and −3.62/−5.82 eV, respectively, as estimated from the thin-film cyclic voltammetry measurements. In the single crystals, both compounds exhibit one dimensional π–π stacking of molecules, and 1 shows the larger π-electron overlap between the neighboring molecules than 2, along with interdigitation of alkyl chains. Thin-film X-ray diffraction (XRD) and atomic force microscopy (AFM) characterizations indicate that 1 can form films with higher molecular order than 2. Field-effect electron mobility up to 0.33 cm2 V−1 s−1 in air for 1 and hole mobility up to 0.05 cm2 V−1 s−1 for 2 have been demonstrated with the top-contact organic thin-film transistor (OTFT) device structure. Electron mobility of 1 is among the highest value for n-type organic semiconductors.
Co-reporter:Aiguo Sui ; Xincui Shi ; Shupeng Wu ; Hongkun Tian ; Yanhou Geng ;Fosong Wang
Macromolecules () pp:
Publication Date(Web):June 22, 2012
DOI:10.1021/ma3009299
A new catalyst system, i.e., nickel acetylacetonate/1,3-bis(diphenylphosphino)propane (Ni(acac)2/dppp), was explored to catalyze the Kumada catalyst transfer polycondensation (KCTP) of three fluorene monomers with different substituents at 9-position. The “living” nature of the polymerization was confirmed by polymerization kinetic studies, “monomer addition” experiment and block copolymerizations. As a result, poly(9,9-dioctylfluorene)s (PF8s) with the number-average molecular weights (Mns) in the range 2.8–62.2 kDa and polydispersity indices (PDIs) of ∼1.20 were successfully synthesized in a controlled manner. The syntheses of fluorene-fluorene and fluorene-thiophene diblock copolymers with Mns up to 46 kDa were also demonstrated. A complex, i.e. Ni(dppp)(acac)2, with an octahedral coordination geometry was isolated and confirmed by X-ray crystallographic analysis. The polymerization experiments indicated that the in situ formed Ni(dppp)(acac)2 should be the active catalyst. To the best of our knowledge, this is the first report on the controlled synthesis of polyfluorenes (PFs) via KCTP.
Co-reporter:Shaoqiang Dong, Hongkun Tian, De Song, Zhenhua Yang, Donghang Yan, Yanhou Geng and Fosong Wang
Chemical Communications 2009(Issue 21) pp:NaN3088-3088
Publication Date(Web):2009/04/14
DOI:10.1039/B822819A
Tetraoctyl-substituted vanadyl phthalocyanine (OVPc4C8) as a new NIR-absorbing discotic liquid crystalline material can form highly ordered thin films with edge-on alignment of the molecules and molecular packing mode identical to that in the phase II of OVPc for solution processed OTFTs with mobility up to 0.017 cm2 V−1 s−1.
![Dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene](/data/chemimg/136100/935280-42-5.png)
![Dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene](/data/chemimg/136100/935280-42-5_b.png)
![Poly[2,7-(9,9-di-octyl-fluorene)-alt-4,7-bis(thiophen-2-yl)benzo-2,1,3-thiadiazole]](/data/chemimg/133300/782469-77-6.png)
![Poly[2,7-(9,9-di-octyl-fluorene)-alt-4,7-bis(thiophen-2-yl)benzo-2,1,3-thiadiazole]](/data/chemimg/133300/782469-77-6_b.png)
![Bicyclo[2.2.1]heptane-2,3-dicarboxylicacid, sodium salt (1:2), (1R,2R,3S,4S)-rel-](http://img.cochemist.com/ccimg/351900/351870-33-2.png)
![Bicyclo[2.2.1]heptane-2,3-dicarboxylicacid, sodium salt (1:2), (1R,2R,3S,4S)-rel-](http://img.cochemist.com/ccimg/351900/351870-33-2_b.png)
![Thieno[3,2-b]thiophene, 3-bromo-](/data/chemimg/10800/25121-83-9.png)
![Thieno[3,2-b]thiophene, 3-bromo-](/data/chemimg/10800/25121-83-9_b.png)
![2H-Indol-2-one, 6-bromo-3-[6-bromo-1,2-dihydro-1-(2-octyldodecyl)-2-oxo-3H-indol-3-ylidene]-7-fluoro-1,3-dihydro-1-(2-octyldodecyl)-](/data/chemimg/3777600/1516887-18-5.png)
![2H-Indol-2-one, 6-bromo-3-[6-bromo-1,2-dihydro-1-(2-octyldodecyl)-2-oxo-3H-indol-3-ylidene]-7-fluoro-1,3-dihydro-1-(2-octyldodecyl)-](/data/chemimg/3777600/1516887-18-5_b.png)
![2H-Indol-2-one, 6-bromo-3-[6-bromo-1,2-dihydro-1-(2-octyldodecyl)-2-oxo-3H-indol-3-ylidene]-1,3-dihydro-1-(2-octyldodecyl)-](/data/chemimg/152100/1263379-85-6.png)
![2H-Indol-2-one, 6-bromo-3-[6-bromo-1,2-dihydro-1-(2-octyldodecyl)-2-oxo-3H-indol-3-ylidene]-1,3-dihydro-1-(2-octyldodecyl)-](/data/chemimg/152100/1263379-85-6_b.png)
![Pyrrolo[3,4-c]pyrrole-1,4-dione, 3,6-bis(5-bromo-2-thienyl)-2,5-bis(2-decyltetradecyl)-2,5-dihydro-](/data/chemimg/3730400/1224430-28-7.png)
![Pyrrolo[3,4-c]pyrrole-1,4-dione, 3,6-bis(5-bromo-2-thienyl)-2,5-bis(2-decyltetradecyl)-2,5-dihydro-](/data/chemimg/3730400/1224430-28-7_b.png)
![2H-Indol-2-one, 6-bromo-3-[6-bromo-1-(2-hexyldecyl)-1,2-dihydro-2-oxo-3H-indol-3-ylidene]-1-(2-hexyldecyl)-1,3-dihydro-](/data/chemimg/3730400/1147124-24-0.png)
![2H-Indol-2-one, 6-bromo-3-[6-bromo-1-(2-hexyldecyl)-1,2-dihydro-2-oxo-3H-indol-3-ylidene]-1-(2-hexyldecyl)-1,3-dihydro-](/data/chemimg/3730400/1147124-24-0_b.png)
![Thieno[3,2-b]thiophene, 2,5-bis(3-dodecyl-2-thienyl)-](/data/chemimg/3755900/928829-00-9.png)
![Thieno[3,2-b]thiophene, 2,5-bis(3-dodecyl-2-thienyl)-](/data/chemimg/3755900/928829-00-9_b.png)
![Poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene]](http://img.cochemist.com/ccimg/888500/888491-19-8.png)
![Poly[2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene]](http://img.cochemist.com/ccimg/888500/888491-19-8_b.png)
![1,3,2-Dioxaborolane, 2-[2,2'-binaphthalen]-6-yl-4,4,5,5-tetramethyl-](http://img.cochemist.com/ccimg/647900/647836-56-4.png)
![1,3,2-Dioxaborolane, 2-[2,2'-binaphthalen]-6-yl-4,4,5,5-tetramethyl-](http://img.cochemist.com/ccimg/647900/647836-56-4_b.png)
![9H-FLUORENE, 2,7-BIS([1,1'-BIPHENYL]-4-YL)-9,9-DIOCTYL-](http://img.cochemist.com/ccimg/415800/415707-99-2.png)
![9H-FLUORENE, 2,7-BIS([1,1'-BIPHENYL]-4-YL)-9,9-DIOCTYL-](http://img.cochemist.com/ccimg/415800/415707-99-2_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)
![Stannane, [2,2'-bithiophene]-5,5'-diylbis[tributyl-](/data/chemimg/105800/171290-94-1.png)
![Stannane, [2,2'-bithiophene]-5,5'-diylbis[tributyl-](/data/chemimg/105800/171290-94-1_b.png)
