Slight Structural Disorder in Bithiophene-based Random Terpolymers with Improved Power Conversion Efficiency for Polymer Solar Cells  

作　　者：Meng-Han Wang Zhong-Yuan Xue Zhi-Wei Wang Wei-Hua Ning Yu Zhong Ya-Nan Liu Chun-Feng Zhang Sven Huettner You-Tian Tao 

机构地区：[1]Key Lab for Flexible Electronics &Institute of Advanced Materials, Jiangsu National Synergistic Innovation Center for Advanced Materials (SICAM), Nanjing Tech University, Nanjing 211816, China [2]National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China [3]Macromolecular Chemistry Ⅰ, Universitat Bayreuth, 30 Universitatsstr, 95447, Bayreuth, Germany

出　　处：《Chinese Journal of Polymer Science》2018年第10期1129-1138,共10页高分子科学（英文版）

基　　金：financially supported by the the National Natural Science Foundation of China(No.61761136013);the Natural Science Foundation of Jiangsu Province(Nos.BK20160042 and BK20160990);DFG(392306670);the CSC for financial support

摘　　要：A series of random terpolymers P2-P5 were designed and synthesized by randomly embedding 5 mol%, 10 mol%, 15 mol% and 25 mol% feed ratios of low cost 2,2-bithiophene as the third monomer to the famous donor-acceptor （D-A） type copolymer PTBT-Th （P1）. All polymers showed similar molecular weight with number-average molecular weight （Mn） and weight-average molecular weight （Mw） in the range of （59-74） and （93-114） kg·mol-1, respectively, to ensure a fair comparison on the structure-property relationships. Compared with the control copolymer PTBT-Th, the random terpolymers exhibited enhanced absorption intensity in a wide range from 400 nm to 650 nm in both solution and film as well as in polymer/PC71BM blends. From grazing incident wide-angle X-ray diffraction （GIWAXS）, compared with the regularly alternated copolymer PTB7-Th, the random terpolymers demonstrated mild structural disorder with reduced （100） lamellar stacking and slightly weakened （010） π-π stacking for the polymers as well as slightly reduced PC71BM aggregation in polymer/PC71BM blends. However, the measured hole mobility for terpolymers （（1.20-3.73） × 10 -4 cm2·V-1·s-1） was evaluated to be comparable or even higher than 1.35 × 10 -4 cm2·V-1 ·s-1 of the alternative copolymer. Enhanced average power conversion efficiency （PCE） from 7.35% to 8.11% and 7.79% to 8.37% was observed in both conventional and inverted device architectures from copolymer P1 to terpolymers P4, while further increasing the 2,2-bithiophene feed ratio decreased the PCE.A series of random terpolymers P2-P5 were designed and synthesized by randomly embedding 5 mol%, 10 mol%, 15 mol% and 25 mol% feed ratios of low cost 2,2-bithiophene as the third monomer to the famous donor-acceptor （D-A） type copolymer PTBT-Th （P1）. All polymers showed similar molecular weight with number-average molecular weight （Mn） and weight-average molecular weight （Mw） in the range of （59-74） and （93-114） kg·mol-1, respectively, to ensure a fair comparison on the structure-property relationships. Compared with the control copolymer PTBT-Th, the random terpolymers exhibited enhanced absorption intensity in a wide range from 400 nm to 650 nm in both solution and film as well as in polymer/PC71BM blends. From grazing incident wide-angle X-ray diffraction （GIWAXS）, compared with the regularly alternated copolymer PTB7-Th, the random terpolymers demonstrated mild structural disorder with reduced （100） lamellar stacking and slightly weakened （010） π-π stacking for the polymers as well as slightly reduced PC71BM aggregation in polymer/PC71BM blends. However, the measured hole mobility for terpolymers （（1.20-3.73） × 10 -4 cm2·V-1·s-1） was evaluated to be comparable or even higher than 1.35 × 10 -4 cm2·V-1 ·s-1 of the alternative copolymer. Enhanced average power conversion efficiency （PCE） from 7.35% to 8.11% and 7.79% to 8.37% was observed in both conventional and inverted device architectures from copolymer P1 to terpolymers P4, while further increasing the 2,2-bithiophene feed ratio decreased the PCE.

关 键 词：Bithiophene-based random terpolymers Structural disorder Polymer solar cells Photovoltaic properties 

分 类 号：TM914.4[电气工程—电力电子与电力传动] O631[理学—高分子化学]