Benzodifuran‐containing well‐defined π‐conjugated polymers for photovoltaic cells |
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Authors: | Hui Li Peng Tang Yan Zhao Shi‐Xia Liu Yves Aeschi Lijun Deng Jörg Braun Bin Zhao Yunqi Liu Songting Tan Wolfgang Meier Silvio Decurtins |
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Institution: | 1. Departement für Chemie und Biochemie, Universit?t Bern, Freiestrasse 3, Bern CH‐3012, Switzerland;2. Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Xiangtan 411105, People's Republic of China;3. Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, People's Republic of China;4. Departement für Chemie, Universit?t Basel, Klingelbergstrasse 80, Basel CH‐4056, Switzerland |
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Abstract: | Two well‐defined alternating π‐conjugated polymers containing a soluble electroactive benzo1,2‐b:4,5‐b′]difuran (BDF) chromophore, poly(BDF‐(9‐phenylcarbazole)) (PBDFC), and poly(BDF‐benzothiadiazole) (PBDFBTD) were synthesized via Sonogashira copolymerizations. Their optical, electrochemical, and field‐effect charge transport properties were characterized and compared with those of the corresponding homopolymer PBDF and random copolymers of the same overall composition. All these polymers cover broad optical absorption ranges from 250 to 750 nm with narrow optical band gaps of 1.78–2.35 eV. Both PBDF and PBDFBTD show ambipolar redox properties with HOMO levels of ?5.38 and ?5.09 eV, respectively. The field‐effect mobility of holes varies from 2.9 × 10?8 cm2 V?1 s?1 in PBDF to 1.0 × 10?5 cm2 V?1 s?1 in PBDFBTD. Bulk heterojunction solar cell devices were fabricated using the polymers as the electron donor and 6,6]‐phenyl‐C61‐butyric acid methyl ester as the electron acceptor, leading to power conversion efficiencies of 0.24–0.57% under air mass 1.5 illumination (100 mW cm?2). These results indicate that their band gaps, molecular electronic energy levels, charge mobilities, and molecular weights are readily tuned by copolymerizing the BDF core with different π‐conjugated units. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 |
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Keywords: | benzodifuran charge transport conjugated polymers copolymerization photovoltaic cells |
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