Organic-inorganic hybrid perovskite solar cells represent an exceptional candidate for next-generation photovoltaic technology. However, the presence of surface defects in perovskite crystals limits the performance as well as the stability of perovskite solar cells. We have employed a series of carbazole and benzothiadiazole (BT) based donor-acceptor copolymers, which have different lengths of alkoxy side-chains grafted on the BT unit, as the dopant-free hole transport materials (HTMs) for perovskite solar cells. We demonstrate that although these side-chains can reduce the π−π stacking structural order of these copolymers to affect the hole transport properties, the methoxy unit introduces a desired defect passivation effect. Compared to the Spiro-OMeTAD-based device, the copolymer with methoxy side-chains on the BT unit (namely PCDTBT1) as the HTM achieved superior power conversion efficiency and stability due to efficient hole transport and the suppression of trap-induced degradation, whilst the copolymer with octyloxy side-chains on the BT unit (namely PCDTBT8) as the HTM lead to poor performance and stability.

有机-无机混合钙钛矿太阳能电池是下一代光伏技术的绝佳候选者。然而，钙钛矿晶体中表面缺陷的存在限制了钙钛矿太阳能电池的性能以及稳定性。我们已经使用了一系列基于咔唑和苯并噻二唑（BT）的供体-受体共聚物，它们具有不同长度的接枝到BT单元上的烷氧基侧链，作为钙钛矿型太阳能电池的无掺杂空穴传输材料（HTM）。我们证明，尽管这些侧链可以降低这些共聚物的π-π堆积结构顺序以影响空穴传输性能，但甲氧基单元却会引入所需的缺陷钝化效果。与基于Spiro-OMeTAD的设备相比，