Two conjugated copolymer donors, PTTABDT and PBTTABDT, based on a fused‐ring azepinedione acceptor unit, 5‐(2‐octyldodecyl)‐4H‐thieno[2′,3′:4,5]thieno[3,2‐c]thieno[2′,3′:4,5]thieno[2,3‐e]azepine‐4,6(5H)‐dione (TTA), are prepared. PTTABDT possesses a conventional donor–acceptor (D–A) structure with one TTA in the repeat unit, while PBTTABDT has a D–A–A structure with two TTAs in the repeat unit. Compared with PTTABDT, PBTTABDT shows a deeper highest occupied molecular orbital (HOMO) level, a narrower bandgap, and a higher hole mobility, and exhibits better performance in bulk heterojunction solar cells. Power conversion efficiencies of 6.18% and 7.81% are achieved from PTTABDT:PC₇₁BM and PBTTABDT:PC₇₁BM solar cells, respectively. The higher performance of PBTTABDT:PC₇₁BM solar cells results from the enhanced open‐circuit voltage (V _oc) and short‐circuit current density ( J _sc).

中文翻译：

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通过D–A–A设计提高环稠环二氮杂二酮共聚物的光伏性能

基于稠合环氮杂二酮受体单元5-（2-辛基十二烷基）-4H-thieno [2'，3'：4,5] thieno [3,2-c] thieno的两个共轭共聚物供体PTTABDT和PBTTABDT制备[2'，3'：4,5]噻吩并[2,3-e]氮杂-4,6（5H）-二酮（TTA）。PTTABDT具有常规的供体-受体（D–A）结构，重复单元有一个TTA，而PBTTABDT具有D–A–A结构，重复单元有两个TTA。与PTTABDT相比，PBTTABDT显示出更深的最高占据分子轨道（HOMO）能级，更窄的带隙和更高的空穴迁移率，并且在体异质结太阳能电池中表现出更好的性能。PTTABDT：PC ₇₁ BM和PBTTABDT：PC ₇₁ BM太阳能电池分别实现6.18％和7.81％的功率转换效率。PBTTABDT：PC ₇₁的更高性能BM太阳能电池来自增强的开路电压（V _oc）和短路电流密度（J _sc）。