Highly Stable FA_xMA_{1 − x}PbI_{3 − x}Br_x–2P Precursor for Crystalizing High-Quality, Large-Area Perovskite Film in an Ambient Atmosphere

Perovskite solar cells (PSCs) are one of the highly promising new-generation photovoltaic technologies. One of the remaining challenges for commercializing PSCs is to prepare high-quality, large-area perovskite films in an ambient atmosphere reproducibly using less toxic materials. Herein, a nonvolatile, less toxic substance, 2-pyrrolidinone (2P), is used as a complexant solvent for the perovskite precursor solution. Combining this with a newly developed spin-assisted solvent extraction (SASE) crystallization method, a high-quality perovskite film is prepared in air reproducibly. The nonvolatile nature of 2P and the formation of MAI–PbI₂–2P adduct widen the time window for antisolvent engineering, and SASE enhances the solvent exchange rate of the precursor film to form a high-quality perovskite film in air. An inverted cell (based on the postsolvent-treated perovskite absorber) exhibits a power conversion efficiency of more than 18%. This film preparation method is feasible for depositing a high-quality mixed-cation or mixed-cation, mixed-halide perovskite film on both PEDOT:PSS and TiO₂ surfaces to fabricate inverted and regular PSCs, respectively, to achieve efficiencies of more than 16%. More importantly, high-quality, large-area MAPbI₃ film is prepared reproducibly in air for fabricating perovskite submodules to achieve an efficiency of 14% (verified at 13.04% after the cell is packed for efficiency evaluation).