The grain surfaces (film surface and grain boundary) of polycrystalline perovskite films are vulnerable sites in solar cells since they pose a high defect density and initiate the degradation of perovskite absorber. Achieving simultaneously defect passivation and grain protection from moisture is crucial for the viability of perovskite solar cells. Here, an in situ cross-linked grain encapsulation (CLGE) strategy that improves both device stability and defect passivation is reported. Cross-linkable semiconducting small molecules are mixed into the antisolvent to uniformly form a compact and conducting cross-linked layer over the grain surfaces. This cross-linked coating layer not only passivates trap states and facilitates hole extraction, but also enhances the device stability by preventing moisture diffusion. Using the CLGE strategy, a high power conversion efficiency (PCE) of 22.7% is obtained in 1.55-eV bandgap planar perovskite solar cells. The unencapsulated devices with CLGE exhibit significantly enhanced device stability again moisture and maintain >90% of their initial PCE after shelf storage under ambient condition for over 10,000 h.

多晶钙钛矿薄膜的晶粒表面（薄膜表面和晶界）是太阳能电池中的脆弱部位，因为它们构成高缺陷密度并引发钙钛矿吸收剂的降解。同时实现缺陷钝化和防潮保护对钙钛矿太阳能电池的生存至关重要。在这里，报告了一种既提高器件稳定性又改善缺陷钝化的原位交联晶粒封装（CLGE）策略。将可交联的半导体小分子混合到抗溶剂中，以在晶粒表面上均匀形成致密且导电的交联层。该交联涂层不仅钝化陷阱态并促进空穴提取，而且还通过防止水分扩散来提高器件稳定性。使用CLGE策略，在1.55-eV带隙平面钙钛矿太阳能电池中获得了22.7％的高功率转换效率（PCE）。带有CLGE的未封装器件在潮湿条件下在环境条件下存放超过10,000小时后，再次展现出显着增强的器件稳定性，并且保持其初始PCE的> 90％。