Electron acceptor units play an important role in the design of donor–acceptor (D–A) type polymers for efficient organic solar cells (OSCs). In this report, with the oxidation of the thiophene moiety, the electron-rich 4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b′]dithiophene (BDT) unit was tuned into electron-deficient 4,8-bis((2-ethylhexyl)oxy)benzo[1,2-b:4,5-b′]dithiophene 1,1,5,5-tetraoxide (BDTO) unit. Two novel polymers of PBDTO and PBDTO-T based on BDTO unit were synthesized and employed as additives in efficient non-fullerene OSCs with the active layer consist of PBDB-T and IT-M. With doping 1% PBDTO or PBDTO-T, the power conversion efficiency (PCE) of the prepared OSCs increased from 10.31% to 11.47% or 11.12%, respectively. These two polymers can afford cascaded energy levels and smooth the surface of the active layer, which are beneficial for better carrier transportation and separation. Our results open a new avenue to construct electron acceptor backbone in the design of D–A type polymers for OSCs.

中文翻译：

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使用4,8-双（（2-乙基己基）氧基）苯并[1,2- b：4,5 - b ']二噻吩基聚合物作为添加剂的高效非富勒烯有机太阳能电池

电子受体单元在用于高效有机太阳能电池（OSC）的供体-受体（D-A）型聚合物的设计中起着重要作用。在此报告中，随着噻吩部分的氧化，富电子的4,8-双（（2-乙基己基）氧基）苯并[1,2- b：4,5- b ']二噻吩（BDT）单元为调谐到缺电子的4,8-双（（2-乙基己基）氧基）苯并[1,2- b：4,5- b′]二噻吩1,1,5,5-四氧化物（BDTO）单元。合成了两种新型的基于BDTO单元的PBDTO和PBDTO-T聚合物，并将其用作有效的非富勒烯OSC中的添加剂，其活性层由PBDB-T和IT-M组成。掺杂1％的PBDTO或PBDTO-T，制备的OSC的功率转换效率（PCE）分别从10.31％提高到11.47％或11.12％。这两种聚合物可以提供级联的能级并平滑活性层的表面，这对于更好的载流子传输和分离是有利的。我们的结果为在OSC的D–A型聚合物设计中构建电子受体主链开辟了一条新途径。