Effects of various donor:acceptor blend ratios on photophysical properties in non-fullerene organic bulk heterojunctions

作     者：Zhenchuan Wen Xuejian Ma Xiaoyu Yang Pengqing Bi Mengsi Niu Kangning Zhang Lin Feng Xiaotao Hao 

作者机构：School of PhysicsState Key Laboratory of Crystal MaterialsShandong UniversityJi'nan 250100China ARC Centre of Excellence in Exciton ScienceSchool of ChemistryThe University of MelbourneParkvilleVictoria3010Australia 

出 版 物：《Chinese Chemical Letters》 (中国化学快报（英文版）)

年 卷 期：2019年第30卷第5期

页      面：995-999页

核心收录：

学科分类：07[理学] 0703[理学-化学] 

基　　金：supported by the National Natural Science Foundation of China(Nos.61631166001,11574181,11774204) Key R&D Programs of Shandong Province,China(No.2018GGX103004) support from the ARC Centre of Excellence in Exciton Science(No.CE170100026) 

主　　题：Photophysical properties Non-fullerene Bulk heterojunctions Various blend ratios Organic solar cells 

摘      要：The composition ratio of donor and acceptor materials in organic bulk heterojunction (BHJ) is one of the key parameters to govern the performance in organic solar cells (OSCs). Therefore, high-performance non-fullerene organic bulk heterojunction consisting of poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b ]dithiophene))-co-(1,3-di(5-thiophene-2-yl)–5,7-bis(2-ethylhexyl) benzo[1,2-c:4,5-c ]dithiophene-4,8-dione)] (PBDB-T) and 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))–5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2 ,3 -d ]-s-indaceno[1,2-b:5,6-b ]-dithio-phene (ITIC) are used to investigate the correlation among various donor: acceptor (D:A) ratios, photophysical properties and photovoltaic performance. Interestingly, the function of short-circuit current (Jsc) and D:A ratios demonstrates an axisymmetric trend. When the blending ratio of D:A deviates from the optimal ratio, the symmetrically decreased Jsc is derived from a reduction in the D:A interface or amorphous region. Research on the steady-state photoluminescence (PL), the time-resolved fluorescence spectroscopy measurements, atomic force microscopic (AFM) and grazing-incidence small angle X-rays scattering (GIWAXS) indicates no significant variation in energy loss in the process of changing D:A ratios in BHJs. With high donor or acceptor content, the domain size improves significantly, but the distance of π-π stacking corresponding to molecular packing has not changed significantly, and the bi-continuous percolation pathways were not obviously influenced.