The poor operational stability of non-fullerene electron acceptor (NFA) organic solar cells (OSCs) currently limits their commercial application. While previous studies have primarily focused on the degradation of the NFA component, we also consider here the electron donor material. We examine the stability of three representative donor polymers, PM6, D18, and PTQ10, paired with the benchmark NFA, Y6. After light soaking PM6 and D18 in air, we find an enhanced conversion of singlet excitons into trapped interchain polaron pairs on sub-100 femtosecond timescales. This process outcompetes electron transfer to Y6, significantly reducing the charge generation yield. However, this pathway is absent in PTQ10. We identify twisting in the benzo[1,2-b:4,5-b′]dithiophene (BDT)-thiophene motif shared by PM6 and D18 as the cause. By contrast, PTQ10 does not contain this structural motif and has improved stability. Thus, we show that the donor polymer can be a weak link for OSC stability, which must be addressed collectively with the NFA.

非富勒烯电子受体 (NFA) 有机太阳能电池 (OSC) 的运行稳定性差，目前限制了它们的商业应用。虽然以前的研究主要集中在 NFA 组件的降解上，但我们在这里也考虑了电子供体材料。我们检查了三种代表性供体聚合物 PM6、D18 和 PTQ10 与基准 NFA Y6 配对的稳定性。在空气中浸泡 PM6 和 D18 后，我们发现在亚 100 飞秒时间尺度上，单线态激子向捕获的链间极化子对的转化增强。这个过程胜过电子转移到 Y6，显着降低了电荷产生率。然而，该途径在 PTQ10 中不存在。我们确定苯并 [1,2- b :4,5- b中的扭曲′]二噻吩 (BDT) - PM6 和 D18 共有的噻吩基序作为原因。相比之下，PTQ10 不包含这种结构基序并且具有更高的稳定性。因此，我们表明供体聚合物可能是 OSC 稳定性的薄弱环节，必须与 NFA 共同解决。