In this study, two novel donor–acceptor (D–A) copolymers are designed and synthesized, DTBT‐2T and DTBT‐2T2F with 2,2′‐bithiophene or 3,3′‐difluoro‐2,2′‐bithiophene as the donor unit and dithienobenzothiadiazole as the acceptor unit, and used them as donor materials in non‐fullerene organic solar cells (OSCs). Due to enhanced planarity of polymer chains resulted by the intramolecular F···S noncovalent interactions, the incorporation of 3,3′‐difluoro‐2,2′‐bithiophene unit instead of 2,2′‐bithiophene into the polymers can enhance their molecular packing, crystallinity and hole mobility. The DTBT‐2T:L8‐BO based binary OSCs deliver a power conversion efficiency (PCE) of only 9.71% with a Voc of 0.78 V, a Jsc of 20.69 mA cm−2, and an FF of 59.67%. Moreover, the introduction of fluoro atoms can lower the highest occupied molecular orbital levels. As a result, DTBT‐2T2F:L8‐BO based single‐junction binary OSCs exhibited less recombination loss, more balanced charge mobility, and more favorable morphology, resulting in an impressive PCE of 17.03% with a higher Voc of 0.89 V, a Jsc of 25.40 mA cm−2, and an FF of 75.74%. These results indicate that 3,3′‐difluoro‐2,2′‐bithiophene unit can be used as an effective building block to synthesize high performance polymer donor materials. This work greatly expands the selection range of donor units for constructing high‐performance polymers.

中文翻译：

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一种基于 3,3'-二氟-2,2'-联噻吩的供体聚合物实现高效率 (>17%) 单结二元有机太阳能电池

在本研究中，设计并合成了两种新型供体-受体（D-A）共聚物：DTBT-2T和DTBT-2T2F，以2,2'-联噻吩或3,3'-二氟-2,2'-联噻吩为供体单元和二噻吩并苯并噻二唑作为受体单元，并将它们用作非富勒烯有机太阳能电池（OSC）中的供体材料。由于分子内F·S非共价相互作用增强了聚合物链的平面性，将3,3'-二氟-2,2'-联噻吩单元代替2,2'-联噻吩引入聚合物中可以增强其性能。分子堆积、结晶度和空穴迁移率。基于 DTBT-2T:L8-BO 的二元 OSC 的功率转换效率 (PCE) 仅 9.71%，V奥克0.78V，一个JSC20.69毫安厘米−2,和FF59.67%。此外，氟原子的引入可以降低最高占据的分子轨道能级。因此，基于 DTBT-2T2F:L8-BO 的单结二元 OSC 表现出更少的复合损失、更平衡的电荷迁移率和更有利的形态，导致令人印象深刻的 17.03% 的 PCE 和更高的V奥克0.89V，一个JSC25.40毫安厘米−2， 和FF75.74%。这些结果表明3,3'-二氟-2,2'-联噻吩单元可以作为合成高性能聚合物供体材料的有效构建单元。这项工作极大地扩展了构建高性能聚合物的供体单元的选择范围。