The first application of isoindigo-based polymers in non-fullerene organic solar cells  

作　　者：Bao Zhang Ning An Hongbo Wu Yanfang Geng Yanming Sun Zaifei Ma Weiwei Li Qiang Guo Erjun Zhou 

机构地区：[1]Henan Institutes of Advanced Technology,Zhengzhou University,Zhengzhou 450003,China [2]CAS Key Laboratory of Nanosystem and Hierarchical Fabrication,CAS Center for Excellence in Nanoscience,National Center for Nanoscience and Technology,Beijing 100190,China [3]School of Chemistry,Beihang University,Beijing 100191,China [4]Center for Advanced Low-dimension Materials,College of Materials Science and Engineering,Donghua University,Shanghai 201620,China [5]State Key Laboratory of Organic-Inorganic Composites,Beijing University of Chemical Technology,Beijing 100029,China

出　　处：《Science China Chemistry》2020年第9期1262-1271,共10页中国科学（化学英文版）

基　　金：the National Key Research and Development Program of China(2017YFA0206600);the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(QYZDB-SSW-SLH033);the National Natural Science Foundation of China(NSFC,51673048,21875052);the Natural Science Foundation of Shanghai(19ZR1401400)。

摘　　要：Although isoindigo(IID)-based polymers can realize high charge mobility,these materials are currently confined to fullerenebased organic solar cells(OSCs).Herein,we designed a pair of alternative D-π-A type copolymers,PE71 and PE72,to expand the application in non-fullerene OSCs,where benzo[1,2-b:4,5-b′]thiophene(BDT),thieno[3,2-b]thiophene(TT)and IID units were used as D,A andπ-bridge,respectively.The aim of optimizing the length of alkyl chains on TT bridge is to ensure polymer solubility,crystallinity as well as miscibility with acceptor molecules.We find that PE71 and PE72 exhibit similar optical and electronic properties,but PE71 with shorter hexyl chain tends to aggregate into fiber-like structure.In the end,Y6 is selected as the electron acceptor because of suitable energy levels and complementary absorption spectrum.Finally,PE71:Y6 device realizes a power conversion efficiency(PCE)of 12.03%,which is obviously higher than that of PE72:Y6 device(9.74%)and is also the highest value for IID-based photovoltaic polymers.The charge transport,molecular aggregation,film morphology and energy loss analysis were systematically investigated.The improved photovoltaic performance of PE71:Y6 mainly originates from the better interpenetrating network structure toward facilitating exciton seperation and free charge carrier transportation.Our results indicate that IID-based D-π-A polymers can also be utilized in non-fullerene OSCs and the alkyl chains on the thieno[3,2-b]thiopheneπ-bridge have a vital effect on the photovoltaic performance.

关 键 词：isoindigo thieno[3 2-b]thiophene alkyl chain non-fullerene organic solar cells 

分 类 号：TM914.4[电气工程—电力电子与电力传动] TQ317[化学工程—高聚物工业]