The Key Role of Subtle Substitution for a High-Performance Ester-Modified Oligothiophene-Based Polymer Used in Photovoltaic Cells  

作　　者：Sunsun Li Yuan Ding Lei Xu Wenchao Zhao Jianqi Zhang Jinzhao Qin Yuyang Zhang Jingjing Zhao Chang He Qiming Peng Jianhui Hou 

机构地区：[1]Key Laboratory of Flexible Electronics(KLOFE)and Institute of Advanced Materials(IAM),Nanjing Tech University(NanjingTech),Nanjing,Jiangsu,211816 China [2]Co-Innovation Center of Efficient Processing and Utilization of Forest Resources,College of Materials Science and Engineering,Nanjing Forestry University,Nanjing,Jiangsu,210037 China [3]State Key Laboratory of Polymer Physics and Chemistry,Beijing National Laboratory for Molecular Sciences,Institute of Chemistry,Chinese Academy of Sciences,Beijing,100190 China [4]Key Laboratory of Nanosystem and Hierarchical Fabrication,National Center for Nanoscience and Technology,Beijing,100190 China [5]Jiangsu Seenbom Flexible Electronics Institute Co.Ltd,Nanjing,Jiangsu,210043 China

出　　处：《Chinese Journal of Chemistry》2022年第24期2867-2874,共8页中国化学（英文版）

基　　金：supported by the National Natural Science Foundation of China(grant nos.51903239,21835006);S.L.also appreciates the Natural Science Foundation of Jiangsu Province(grant no.BK20221317);the startup funding from Nanjing Tech University.

摘　　要：In organic solar cells (OSCs), developing high-performing easily synthesized photoactive materials is essential for pursuing cost- effective balance. Herein, we have designed and synthesized a pair of wide-band-gap polymers (PBDE4T-0F and PBDE4T-2F), using the low synthesis cost dicarboxylic ester-substituted quaterthiophene as the building block. Despite the minor change of molecular structure for polymer PBDE4T-xF, the fluorine substituent in polymer PBDE4T-2F greatly enhances its interchain aggregation. The higher aggregation tendency of ester-modified polymer in solution is beneficial for reducing both the aggregate size and π-π stacking distance of blend film, which contribute to the highly efficient exciton dissociation and symmetric charge transport. An impressive power-conversion efficiency (PCE) of 16.1% is achieved for the PBDE4T-2F:BTP-eC9-based device, while its counterpart only delivers a PCE of 5.8% with distinctly lower short-circuit current density (J_(sc)) and fill factor. Notably, the aggregation effect of donor polymer has also been found to be associated with the energy level shifts, and thus the variation of charge transfer energy and voltage losses for blend system. The results suggest that simultaneously reduced voltage loss and increased J_(sc) can be expected by further finely tuning the aggregation behavior of the ester-modified oligothiophene-based donor polymer.

关 键 词：Organic solar cells Polymers Ester-modified oligothiophene FLUORINE Aggregation 

分 类 号：O62[理学—有机化学]