Synthesis of phenanthro[1,10,9,8‐cdefg]carbazole‐based conjugated polymers for organic solar cell applications |
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Authors: | Chan Woo Jeon Honggon Kim Min Jae Ko Doh‐Kwon Lee Jin Young Kim Hae Jung Son Soon‐Ki Kwon Yun‐Hi Kim BongSoo Kim |
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Institution: | 1. Department of Chemistry, Gyeongsang National University, , JinJu, 660–701 Korea;2. Photo‐electronic Hybrids Research Center, Korea Institute of Science and Technology (KIST), , Seoul, 136–791 Republic of Korea;3. School of Materials Science and Engineering, Engineering Research Institute, Gyeongsang National University, , Jinju, 660–701 Korea |
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Abstract: | Low bandgap polymers with dithienylquinoxaline moieties based on 6H‐phenanthro1,10,9,8‐cdefg]carbazole were synthesized via the Suzuki coupling reaction. Alkoxy groups were substituted at two different positions on the phenyl groups of the quinoxaline units of these polymers: in the para‐position (PPQP) and in the meta‐position (PPQM). The two polymers showed similar physical properties: broad absorption in the range of 400–700 nm, optical bandgaps of ~1.8 eV, and the appropriate frontier orbital energy levels for efficient charge transfer/separation at polymer/PC71BM interfaces. However, the PPQM solar cell achieved a higher PCE due to its higher Jsc. Our investigation of the morphologies of the polymer:PC71BM blend films and theoretical calculations of the molecular conformations of the polymer chains showed that the polymer with the meta‐positioned alkoxy group has better miscibility with PC71BM than the polymer with the para‐positioned alkoxy group because the dihedral angle of its phenyl group with respect to the quinoxaline unit is higher. This higher miscibility resulted in a polymer:PC71BM blend film with a better morphology and thus in a higher PCE. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 796–803 |
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Keywords: | atomic force microscopy (AFM) conjugated polymers degree of polymerization (DP) fullerenes gel permeation chromatography low bandgap polymer solar cells power conversion efficiency push– pull type copolymer quinoxaline |
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