Humidity-Assisted Chlorination with Solid Protection Strategy for Efficient Air-Fabricated Inverted CsPbI₃ Perovskite Solar Cells

Humidity-assisted chlorination with solid protection via 1,2-bis(chlorodimethylsilyl)ethane (Si–Cl) incorporation is demonstrated as an effective strategy to address water erosion for efficient air-fabricated inverted CsPbI3 perovskite solar cells (PSCs). Si–Cl molecules can rapidly react with water to reduce moisture erosion during deposition in air. In addition, the hydrolysis production of hydrogen chloride (HCl) can chlorinate CsPbI3 while the spontaneous polymerization of 1,2-bis(hydroxydimethylsilyl)ethane (Si–OH) builds a solid protection, which would improve the crystallization and phase stability of CsPbI3. Therefore, a champion efficiency of 18.93% with high open-circuit voltage of 1.176 V is achieved, which is the highest efficiency among the inverted inorganic PSCs. Furthermore, the moisture tolerance of both the CsPbI3 films and air-fabricated PSCs gets significant improvement. In addition, the nonencapsulated device shows good operational stability without efficiency drop after 1 sun illumination at 65 °C for 900 h.