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. Editor's summary: Laser annealing of perovskite films under ambient conditions forms crystalline films and avoids degradation products that form under thermal annealing. Chu et al. used grazing-incidence wide-angle x-ray spectroscopy to reveal a roughly 2-minute window in which the impacts of water and oxygen were mitigated. Annealing films with a nanosecond laser for 25 seconds could complete crystal growth and prevent the formation of a hexagonal perovskite phase. A 100-square-centimeter rigid module had a power conversion efficiency of 24%. —Phil Szuromi [ABSTRACT FROM AUTHOR]