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).