Intercepting the Chelation of Perovskites with Ambient Moisture through Active Addition Reaction for Full‐Air‐Processed Perovskite Solar Cells

Abstract The fabrication of perovskite solar cells (PSCs) under full‐air conditions accelerates their scalable production and industrialization. However, ambient moisture interacts with perovskites during the film formation that disturbs their crystallization and triggers structural imperfections. Here, a formamidine (FA) active addition reaction (FAAR) strategy is devised to intercept the deleterious chemical coordination. The simultaneous incorporation of 2, 6‐bis(aminomethyl)pyridine (BAMPy) molecule into tin oxide surface and perovskite bulk ameliorates the interface contact and film interior. It is found that the tail amino group from BAMPy selectively reacts with FA cation, occupying A site of perovskite crystals, increasing binding energy of perovskite with H 2 O molecule even in a defective surface, thereby strengthening moisture tolerance. This strategy effectively modifies perovskite crystallization in ambient air, favors structural uniformity, and forms the compressive‐strained films. The FAAR‐modified PSC devices fabricated under full‐air conditions deliver the highest efficiencies of 24.11% and 21.68% with aperture areas of 0.06 and 1 cm 2 , respectively. The favorable moisture impediment property contributes to perovskite crystallization enhancement and structural uniformity, maintaining 90.8% of their initial performance for the encapsulated devices after 2400 h storage under accelerating damp‐heat measurements (85 °C and 85% relative humidity).