Perfluoroalkylsulfonyl ammonium for humidity- resistant printing high-performance phase-pure FAPbI3 perovskite solar cells and modules

High-quality phase-pure formamidinium lead triiodide (FAPbI₃) perovskite film needs to be fabricated under strict control of the surrounding atmosphere, which becomes more rigorous when large-area FAPbI₃ film is involved, leading to high-performance FAPbI₃ perovskite solar cells and modules predominantly carried out in an inert gas-filled atmosphere. In this work, we propose a scalable printing strategy for the large-area high-quality phase-pure FAPbI₃ film under a high-humidity atmosphere (up to 75% ± 5% relative humidity) by regulating the perovskite precursor ink with a functional perfluoroalkylsulfonyl quaternary ammonium iodide. This approach decreases the energy barriers of cubic phase formation and heterogeneous nucleation, thereby regulating the FAPbI₃ crystallization. The printed photovoltaic small-area cells and large-area modules achieved remarkable power conversion efficiencies of 24.37% and 22.00%, respectively. Specifically, the unencapsulated device exhibits superior operational stability with T₉₀ > 1,060 h, ambient stability with T₉₀ > 2,020 h, and thermal stability with T₉₀ > 2,350 h.