Natural illumination variations in light-dark cycles induce irreversible ion migration in perovskite solar cells, posing substantial challenges to their long-term outdoor operational stability. We addressed this issue by isolating defective octahedra at the perovskite surface using a vapor-deposited polydentate ligand. Surface octahedra isolation suppresses ion migration into the charge transport layer and reduces surface ionic defects, modulating the kinetics of ion migration during light-dark cycles. Our 785-square-centimeter industrial-scale perovskite solar modules achieved a power conversion efficiency (PCE) of 19.6%. Our modules demonstrated enhanced diurnal stability, retaining more than 97% of their initial PCE even after 101 light-dark cycles at 50°C. Our perovskite modules maintained stable power output during 45 days of outdoor operation under severe summer conditions, exhibiting stability comparable with that of the reference silicon cell.

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• DOI: 10.1126/science.adv4280