Replacing alkyl side chain of non-fullerene acceptor with siloxane-terminated side chain enables lower surface energy towards optimizing bulk-heterojunction morphology and high photovoltaic performance  

作　　者：Rihang Qiu Zhuhao Wu Suhan Li Haiying Jiang Qian Wang Yinchu Chen Xuanchen Liu Lianjie Zhang Junwu Chen 

机构地区：[1]State Key Laboratory of Luminescent Materials&Devices,Institute of Polymer Optoelectronic Materials&Devices,Guangzhou 510640,China [2]South China University of Technology,South China Institute of Collaborative Innovation,Dongguan 523808,China

出　　处：《Science China Chemistry》2021年第7期1208-1218,共11页中国科学（化学英文版）

基　　金：supported by the National Natural Science Foundation of China(51521002,U1401244,51673070);the National Key Research and Development Program of China(2019YFA0705900);the Basic and Applied Basic Research Major Program of Guangdong Province(2019B030302007)。

摘　　要：Towards a good control of the morphology of bulk-heterojunction(BHJ)active layers for polymer solar cells(PSCs),selecting an appropriate side chain for a polymer donor and a nonfullerene acceptor(NFA)is very crucial.In this work,two novel NFAs i-IE-4F and i-IESi-4 F comprising alkyl and siloxane-terminated side chains on the central indacenodithiophene(IDT)core,respectively,were synthesized.Attaching the siloxane-terminated side chain to i-IESi-4 F affords surface energy(γ)of33.32 mN/m,much lower than that of 39.83 mN/m for i-IE-4F,supplying a big chance to tune miscibility with a polymer donor.Two fluorobenzotriazole-based polymer donors J52 and PBZ-2Si bearing alkyl and siloxane-terminated side chains,respectively,showγvalues of 36.08 and 33.10 mN/m,respectively.The estimated Flory-Huggins interaction parameters(χD,A)indicate that the i-IESi-4 F is more miscible than i-IE-4F in pairing with J52 or PBZ-2Si.The resulting i-IESi-4 F-based blend film exhibits low film roughness and accompanies obviously improved BHJ uniformity.In PSCs,the J52:i-IESi-4F and PBZ-2Si:i-IESi-4 F active layers display power conversion efficiencies(PCEs)of 12.67%and 14.54%,respectively,all remarkably higher than PCEs≤7.34%of the i-IE-4F-based active layers.Interestingly,the PBZ-2Si:i-IESi-4 F active layer,a donor:acceptor blend system comprising siloxane-terminated side chains(DSi:ASimatching)with the highest BHJ miscibility due to the combinatory effect of the side chains,shows the highest efficiency,as supported by efficient exciton dissociation,the lowest bimolecular recombination,and the optimal charge transport.Our results demonstrate that attaching siloxane-terminated side chains to NFAs,as a side chain engineering,has big potential in lowering their surface energy towards fine control of BHJ morphology and leading to a better donor:acceptor blend system.

关 键 词：terminated ACCEPTOR DONOR 

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]