Fabrication of efficient and stable perovskite solar cells in high-humidity environment through trace-doping of large-sized cations

Solution-processed organic–inorganic lead halide perovskites have shown photovoltaic performance above 23 %, attracting great attention. However, the champion devices require fabrication in a controlled inert/dry atmosphere. The development of highly efficient and stable perovskite solar cells under high-humidity atmosphere conditions for future commercialization is still challenging, especially for CH₃NH₃PbI₃ (MAPbI₃), which is vulnerable to moisture. In this study, a large-sized tert-butylammonium [C(CH₃)₃NH₃⁺] organic cation was incorporated into the MAPbI₃ crystalline structure, which could form a more stable 3 D crystalline structure and alleviate the decomposition caused by the humidity. It delivered a power conversion efficiency of 19.3 % upon preparation under a humid environment condition of 50 % relative humidity as well as improved humidity and thermal stability. Our work provides a facile strategy for improving perovskite performance and stability by introducing a new chemical additive for the future application of perovskite solar cells.