Molecular design of either polymer donors or acceptors is a promising strategy to tune the morphology of the active layer of organic solar cells, enabling a high-performance device. Thereinto, developing novel polymer donors is an alternative method to obtain high photovoltaic performance. Herein, we present a facile side-chain engineering on the dithiophenobenzotriazole (DTBTz) unit of newly-designed polymer donors (named pBDT-DTBTz-EH and pBDT-DTBTz-Me) to boost the performance of non-fullerene solar cells. Compared with pBDT-DTBTz-EH with long N-alkyl side chains, pBDT-DTBTz-Me with a short methyl exhibits stronger molecular aggregation, higher absorption coefficient, and preferred face-on orientation packing. As a consequence, pBDT-DTBTz-Me based devices achieve an optimal power conversion efficiency of 15.31% when donors are paired with the narrow bandgap acceptor Y6, which is superior to that of pBDT-DTBTz-EH based devices (9.17%). Additionally, the pBDT-DTBTz-Me based devices manifest more effective charge separation and transfer than pBDT-DTBTz-EH based devices. These results indicate that fine-tuning side chains of polymer donors provide new insights for the design of high-performance polymer donors in non-fullerene solar cells.

聚合物供体或受体的分子设计是调整有机太阳能电池活性层形态、实现高性能器件的一种很有前景的策略。其中，开发新型聚合物供体是获得高光伏性能的替代方法。在此，我们在新设计的聚合物供体（命名为 pBDT-DTBTz-EH 和 pBDT-DTBTz-Me）的二噻吩苯并三唑 (DTBTz) 单元上提出了一种简便的侧链工程，以提高非富勒烯太阳能电池的性能。与具有长 N-烷基侧链的 pBDT-DTBTz-EH 相比，具有短甲基的 pBDT-DTBTz-Me 表现出更强的分子聚集、更高的吸收系数和优选的正面取向堆积。因此，基于 pBDT-DTBTz-Me 的设备实现了 15 的最佳功率转换效率。当供体与窄带隙受体 Y6 配对时为 31%，优于基于 pBDT-DTBTz-EH 的器件 (9.17%)。此外，基于 pBDT-DTBTz-Me 的器件表现出比基于 pBDT-DTBTz-EH 的器件更有效的电荷分离和转移。这些结果表明，聚合物供体的微调侧链为非富勒烯太阳能电池中高性能聚合物供体的设计提供了新的见解。