Surface-confined protection stabilizes pre-annealing crystallization for ambient blade-coated perovskites

Scalable manufacturing of perovskite solar cells is fundamentally limited by the vulnerability of perovskite crystallization to ambient moisture and oxygen, particularly during blade coating where an extended pre-annealing interval exposes unstable intermediates. Here, we introduce a surface-confined protection strategy to intrinsically stabilize perovskite film formation under ambient conditions. By introducing dipropylammonium trifluoroacetate (DPTA) into the perovskite precursor ink to spontaneously form a dense and self-assembled surface layer, selectively shielding the wet perovskite pre-film from environmental attack during the critical pre-annealing stage. This transient yet effective barrier preserves the PbI₂·NMP intermediate to prevent pre-annealing degradation of the perovskite lattice even at high humidity. Simultaneously, the multifunctional ionic nature of DPTA allows strong coordination and hydrogen-bonding interactions with the perovskite lattice, leading to reduced bulk and interfacial defects. As a result, air-processed blade-coated MA-free perovskite solar cells reach an efficiency of 26.14% (certified at 25.75%), and retain 93.11% of the initial efficiency after 1300 h under continuous 1 sun illumination tested at maximum-power-point. The strategy readily translates to manufacturing-relevant perovskite solar modules, delivering 22.72%-efficiency on substrate area of 100 × 100 mm². These results establish surface-confined protection as a general principle for scalable perovskite photovoltaics under ambient conditions.