- Dithieno[2,3-d:2',3'-d']benzo[1,2-b:4,5-b']dithiophene (DTBDAT)-based copolymers for high-performance organic solar cells
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P(BDT-TCNT) and P(DTBDAT-TCNT), which has an extended conjugation length, were designed and synthesized for applications in organic solar cell (OSCs). The solution absorption maxima of P(DTBDAT-TCNT) with the extended conjugation were red-shifted by 5–15 nm compared with those of P(BDT-TCNT). The optical band gaps and highest occupied molecular orbital (HOMO) energy levels of both P(BDT-TCNT) and P(DTBDAT-TCNT) were similar. The structure properties of thin films of these materials were characterized using grazing-incidence wide-angle X-ray scattering and tapping-mode atomic force microscopy, and charge carrier mobilities were characterized using the space-charge limited current method. OSCs were formed using [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) as the electron acceptor and 3% diphenylether as additive suppress aggregation. OSCs with P(BDT-TCNT) as the electron donor exhibited a power conversion efficiency (PCE) of 4.10% with a short-circuit current density of JSC = 9.06 mA/cm2, an open-circuit voltage of VOC = 0.77 V, and a fill factor of FF = 0.58. OSCs formed using P(DTBDAT-TCNT) as the electron donor layer exhibited a PCE of 5.83% with JSC = 12.2 mA/cm2, VOC = 0.77 V, and FF = 0.62.
- Lee, Ye Seul,Song, Seyeong,Yoon, Yung Jin,Lee, Yun-Ji,Kwon, Soon-Ki,Kim, Jin Young,Kim, Yun-Hi
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- Donor-acceptor conjugated polymer based on naphtho[1,2- c:5,6- c ]bis[1,2,5]thiadiazole for high-performance polymer solar cells
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Donor-acceptor conjugated polymers PBDT-DTBT and PBDT-DTNT, based on 2,1,3-benzothiadiazole (BT) and naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole (NT), have been designed and synthesized for polymer solar cells. NT contains two fused 1,2,5-thiadiazole rings that lower the band gap, enhance the interchain packing, and improve the charge mobility of the resulting polymer. Consequently, the NT-based polymer PBDT-DTNT exhibited considerably better photovoltaic performance with a power conversion efficiency (PCE) of 6.00% when compared with the BT-based polymer PBDT-DTBT, which gave a PCE of 2.11% under identical device configurations.
- Wang, Ming,Hu, Xiaowen,Liu, Peng,Li, Wei,Gong, Xiong,Huang, Fei,Cao, Yong
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- Influence of molecular structure on the performance of low: V oc loss polymer solar cells
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Two regioregular narrow bandgap conjugated polymers (PM1 and PM2) containing the repeat unit BDT-PT-CPDT-PT (BDT = benzodithiophene, PT = pyridyl[2,1,3]thiadiazole, CPDT = cyclopentadithiophene) and different solubilizing alkyl side chains were prepared with the goal of understanding how chemical structure impacts the performance of low Voc loss bulk heterojunction (BHJ) solar cells containing PC61BM as the acceptor semiconductor. Both polymers show nearly identical orbital energy levels, a face-on orientation relative to the surface normal, and can be processed to yield continuous fiber-like networks in the active layer. Due to the choice of repeat units within the backbone structure, PM1 and PM2 exhibit shorter π-π stacking distances, relative to the previously reported low Voc loss regioregular polymer PIPCP. Finally, PM1 achieves an average PCE of 6.2 ± 0.2% and PM2 achieves an average PCE of 7.2 ± 0.1%. Devices exhibit low Voc loss and high short circuit current Jsc, but, most significantly, display improved fill factors compared to previously reported PIPCP. A discussion is provided that seeks to identify structural features in conjugated polymers that lead to devices with low Voc loss and high external quantum efficiencies.
- Wang, Ming,Wang, Hengbin,Ford, Michael,Yuan, Jianyu,Mai, Cheng-Kang,Fronk, Stephanie,Bazan, Guillermo C.
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supporting information
p. 15232 - 15239
(2016/10/13)
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