Synergistic In Situ Hydrolysis Polymerization for Efficient Air-Fabricated Inorganic Perovskite Solar Cells

Inorganic lead halide perovskites, especially CsPbI 3 , have witnessed significant progress in photovoltaic field due to their outstanding optoelectronic properties and high thermal stability. However, high-performance inorganic perovskite solar cells (IPSCs) are generally realized by strictly controlling the environmental humidity (mostly lower than 40%) during fabrication, which is undesirable for reducing fabrication cost and promoting further industrial production. Herein, a synergistic in situ hydrolysis polymerization strategy through 3,3,3-(trifluoropropyl)trichlorosilane (TFCS) and (3-2-aminoethylamino)propyltrimethoxysilane (AEMS) treatment is reported to prevent water invasion and realize efficient CsPbI 3 IPSCs in highly humid air. TFCS not only regulates the crystallization process via hydrolysis reaction, but also stabilizes the phase structure by passivating the defects and producing a hydrophobic protection layer. Additionally, TFCS facilitates in situ polymerization of upper layer AEMS, thus promoting further enhanced protection of perovskites against ambient moisture. As a result, the CsPbI 3 IPSCs fabricated at 45% humidity exhibit a dramatically improved efficiency of 20.09%, representing a record value for the inverted IPSCs fabricated in air with humidity over 40%. Moreover, the environmental humidity window for device fabrication can be broadened to 60%. This work provides an effective approach to stabilizing air-processed CsPbI 3 and favoring the practical industrial manufacture to further boost their cost-effective applications.