Reduced exciton binding energy and diverse molecular stacking enable high-performance organic solar cells with V_(OC)over 1.1 V  

作　　者：Tingting Dai Jiahao Lu Ailing Tang Yuhan Meng Peiqing Cong Zongtao Wang Erjun Zhou 

机构地区：[1]National Center for Nanoscience and Technology,Beijing 100190,China [2]Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China [3]College of Chemistry and Chemical Engineering,Guangxi Minzu University,Nanning 530006,China [4]Henan Institute of Advanced Technology,Zhengzhou University,Zhengzhou 450003,China

出　　处：《Science China Chemistry》2024年第9期3140-3152,共13页中国科学（化学英文版）

基　　金：supported by the National Natural Science Foundation of China(21875052,51873044)。

摘　　要：High-voltage organic solar cells(OSCs)have received increasing attention because of their promising applications in tandem devices and indoor photovoltaics,but the trade-off between energy loss and charge generation induced by exciton binding energy(E_(b))has become one of the biggest bottlenecks limiting the development of this field.Here,a wide bandgap(WBG)nonfullerene acceptor BTA503 with reduced E_(b) is designed by changing the phenyl side chain on the central core of Cl-BTA5 to an alkyl chain.The diverseπ-πinteractions and enhanced molecular stacking of BTA503 are responsible for its reduced E_(b).Furthermore,both the diminished charge recombination and the fast exciton dissociation caused by the small E_(b) favor the generation of more charge carriers for the PTQ10:BTA503 combination.The efficient Forster resonance energy transfer(FRET)and multiple π-π stacking patterns provide additional charge transfer and transport pathways.Ultimately,the PTQ10:BTA503-based OSC device achieves a V_(OC)of 1.112 V and a PCE of 12.70%,which is higher than that of PTQ10:Cl-BTA5(PCE=10.92%).Simultaneously,the thick film(~300 nm)binary device of PTQ10:BTA503 achieves a PCE of 10.13% with a V_(OC)of 1.102 V,which is the best result for thick film high-voltage OSCs.More importantly,the ternary device of PTQ10:BTA503:Cl-BTA5(1:0.9:0.1)realizes a champion PCE of 13.12% with a V_(OC)of 1.126 V.Our study demonstrates that it is an effective strategy to reduce E_(b) of A_(2)-A_(1)-D-A_(1)-A_(2) type WBG acceptors by modulating the side chains on D unit,which further favors the corresponding devices to obtain world-record PCE and improves their potential for commercial applications.

关 键 词：exciton binding energy intermolecular interaction wide-bandgap acceptor high V_(OC) organic solar cells 

分 类 号：TM914.4[电气工程—电力电子与电力传动] O641.3[理学—物理化学]