CsPbI3perovskite solar module with certified aperture area efficiency >18% based on ambient-moisture-assisted surface hydrolysis

Humidity can accelerate degradation by promoting phase transitions and enhancing the defect generation in perovskites. This poses a significant challenge for the upscaling of perovskite solar modules under ambient conditions, especially for moisture-sensitive inorganic CsPbI3perovskite. Herein, we report an environmental moisture-induced chemical passivation of the CsPbI3perovskite surface by the hydrolysis of perfluorobutanesulfonyl chloride (PFSC). The in situgenerated perfluorobutanesulfonic acid (PFS) effectively reduces defect density and improves the interfacial contact, leading to CsPbI3-based devices with suppressed non-radiative recombination losses. Our in situsurface-modified PFS-CsPbI3perovskite solar modules with an aperture area of 12.82 cm2deliver a state-of-the-art certified aperture area efficiency of 18.22%.