Inner side-chain engineering on Y6 has been proven successful in improving short-circuit current density (J_SC) through fine-tuning aggregated structures of acceptors. However, it fails in tuning the lowest unoccupied molecular orbital level (LUMO) and open-circuit voltage (V_OC). In this paper, we turn to focus on engineering the outer side chains on the flanking thienothiophene units with 4-hexylphenyl (PhC6) and 6-phenylhexyl (C6Ph) chains. Use of PhC6 enhances the steric effect between the attached phenyl and the ending group, which in combination with the additional conjugation effect provided by the linking phenyl leads to upshifted energy levels and increased V_OC as a result. Again, substitution with the bulkier PhC6 unprecedentedly improves film-morphology with reduced paracrystalline disorder and long period and increased root-mean-square composition variations as well, leading to increased electron and hole mobilities and suppressed monomolecular recombination with J_SC and fill-factor (FF) simultaneously enhanced. The PM6:BTP-PhC6-based devices yield a higher efficiency value of 16.7% than the PM6:BTP-C6Ph-based one (15.5%). Therefore, this study shows a conceptual advance in materials design towards reducing the conflict between V_OC and J_SC in binary blended organic solar cells, which can be achieved by introducing bulkier chains to twist the backbone and simultaneously enhance the packing order.

已证明，通过微调受体的聚集结构，Y6上的内部侧链工程成功改善了短路电流密度（J _SC）。但是，它未能在调谐最低未占分子轨道能级（LUMO）和开路电压（V _OC）。在本文中，我们将重点放在用4-己基苯基（PhC6）和6-苯基己基（C6Ph）链设计侧接噻吩并噻吩单元的外侧链上。使用PhC6会增强连接的苯基与末端基团之间的空间效应，这与连接苯基所提供的附加共轭效应相结合会导致能量水平升高和V _OC升高结果是。再次，用更大的PhC6替代物以前所未有的方式改善了膜的形貌，同时减少了顺晶无序性和降低了周期，并增加了均方根组成变化，从而导致电子和空穴迁移率提高，并抑制了J _SC和填充因子的单分子重组（ FF）同时增强。与基于PM6：BTP-C6Ph的设备（15.5％）相比，基于PM6：BTP-PhC6的设备产生的效率值为16.7％。因此，本研究显示了材料设计在减少V _OC和J _SC之间的冲突方面的概念性进展。 在二元混合有机太阳能电池中，可以通过引入较大的链来扭曲主链并同时提高堆积顺序来实现。