All-inorganic CsPbI₂Br material has attracted considerable attention due to its good balance between phase stability and absorption capacity. However, the power conversion efficiency (PCE) and device stability of CsPbI₂Br-based perovskite solar cells (PSCs) still lag far behind those of their counterparts, mainly deriving from the notoriously poor moisture stability under humid environment and large serious charge recombination. Herein, a typical phenethylammonium chlorine (PEACl) and its fluorinated derivative 4-fluoro-phenethylammonium chlorine (F-PEACl) are individually incorporated to modify the surface of CsPbI₂Br film to ameliorate the above issues. Benefiting from the comprehensive passivation effect of ammonium halogen, the trap states of treated CsPbI₂Br are vastly suppressed. In particular, fluorination significantly increased the dipole moment and hydrophobic property of F-PEACl. Thus, the present CsPbI₂Br PSC achieves a champion PCE of 16.29% with high open-circuit voltage of 1.272 V, while the reference device and PEACl-treated device yield PCEs of 14.30% and 15.64%, respectively. More importantly, the PSC with F-PEACl capping layer retains 87.2% of its initial PCE after 1000 h storage under 20% RH ambient without encapsulation. Our results reveal the underlying mechanism of performance improvement by surface passivation strategy and provide an effective approach to further boost the CsPbI₂Br PSC efficiency and stability.

全无机CsPbI ₂ Br 材料由于其在相稳定性和吸收能力之间的良好平衡而引起了相当多的关注。然而，CsPbI ₂ Br 基钙钛矿太阳能电池（PSCs）的功率转换效率（PCE）和器件稳定性仍远远落后于同类产品，主要是由于潮湿环境下众所周知的水分稳定性差和大量严重的电荷复合。在本文中，典型的苯乙基氯铵 (PEACl) 及其氟化衍生物 4-氟-苯乙基氯铵 (F-PEACl) 分别掺入以修饰 CsPbI ₂的表面Br膜改善了上述问题。受益于卤素铵的综合钝化作用，处理后的 CsPbI ₂ Br的陷阱态被大大抑制。特别是，氟化显着增加了 F-PEACl 的偶极矩和疏水性。因此，目前的 CsPbI ₂Br PSC 在 1.272 V 的高开路电压下实现了 16.29% 的 PCE，而参考器件和 PEACl 处理的器件分别产生了 14.30% 和 15.64% 的 PCE。更重要的是，在没有封装的情况下，在 20% RH 环境下储存 1000 小时后，具有 F-PEACl 覆盖层的 PSC 保留了其初始 PCE 的 87.2%。我们的结果揭示了通过表面钝化策略提高性能的潜在机制，并提供了一种有效的方法来进一步提高 CsPbI ₂ Br PSC 的效率和稳定性。