Laser annealing enables rapid, degradation-free ambient processing of perovskite solar modules

Unlike small-area perovskite films produced by spin coating, which undergo prolonged thermal annealing in inert atmosphere for full crystallization, printable perovskite photovoltaics face a critical trade-off between crystal growth quality and ambient degradation from water and oxygen exposure. Through in situ grazing-incidence wide-angle x-ray scattering analysis, we reveal a four-stage degradation mechanism during thermal processing and identify a 123 ± 18–second ambient degradation-free window where water and oxygen effects are mitigated. The laser annealing (455-nanometer wavelength, 20 watts per square centimeter) provides irradiance that is two orders of magnitude higher than that of conventional thermal methods (0.06 watts per square centimeter), which prevents 6H perovskite phase accumulation. The strategy yields power conversion efficiencies of 24.0% (in a 100–square centimeter rigid module) and 20.7% (in a flexible counterpart), representing high reported values for scalable perovskite photovoltaics.