Thiazolothiazole‐containing polythiophenes with low HOMO level and high hole mobility for polymer solar cells |
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Authors: | Qinqin Shi Haijun Fan Yao Liu Jianming Chen Zhigang Shuai Wenping Hu Yongfang Li Xiaowei Zhan |
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Institution: | Beijing National Laboratory for Molecular Sciences and Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China |
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Abstract: | Two regiochemically defined polythiophenes containing thiazolothiazole acceptor unit were synthesized by palladium(0)‐catalyzed Stille coupling reaction. The thermal, electrochemical, optical, charge transport, and photovoltaic properties of these copolymers were examined. Compared to P1 with head‐to‐head coupling of two middle thiophenes, P2 with head‐to‐tail coupling of two middle thiophenes exhibits 40 nm red shift of absorption spectrum in film and 0.3 eV higher HOMO level. Both polymers exhibit field‐effect hole mobility as high as 0.02 cm2 V?1 s?1. Polymer solar cells (PSCs) were fabricated based on the blend of the polymers and methanofullerene6,6]‐phenyl C71‐butyric acid methyl ester (PC71BM). The PSC based on P1 :PC71BM (1:2, w/w) exhibits a power conversion efficiency of 2.7% under AM 1.5, 100 mW cm?2, two times of that based on P2 :PC71BM. The higher efficiency is attributed to lower HOMO (?5.6 eV) and smaller phase separation scale in P1 :PC71BM blend. Tiny change in thiophene connection of P1 and P2 lead to great difference in HOMO, phase separation scale, and efficiency of their photovoltaic devices. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 |
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Keywords: | conjugated polymer field‐effect transistor polymer solar cell polythiophene structure– property relations synthesis thiazolothiazole |
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