• A self-buffered molecular migration strategy is developed to suppress spontaneous intermolecular exchange between perovskite intermediate phase and ambient moisture.
• Exceptionally broad nucleation time and humidity tolerance windows are achieved for perovskite crystallization under ambient air conditions, with 1.68 eV-bandgap PSCs reaching a record efficiency of 22.09% at 50–60% relative humidity.
• The strategy is broadly applicable to 1.53 eV- and 1.77 eV-bandgap perovskite films, enabling high-efficiency PSCs via air-based crystallization processing.
• The n-i-p structured PSCs based on 1.53 eV- and 1.77 eV-bandgap perovskite films achieve outstanding reverse-scan PCEs of 25.23% and 19.09%, respectively, surpassing state-of-the-art ambient-air processed PSCs.