CsPbI3 perovskite solar module with certified aperture area efficiency >18% based on ambient-moisture-assisted surface hydrolysis

Context & scaleIn today's energy context, the upscaling of solar cells is particularly important. Although the efficiency of the solar cells based on inorganic perovskite CsPbI3 has made continuous progress, the module-related research is still lagging. We significantly improved the performance of the CsPbI3-based module through an ambient-moisture-assisted in situ chemical hydrolysis strategy. Specifically, for the first time, we used perfluorobutanesulfonyl chloride that is hydrolyzable for surface passivation. Our solar module with an aperture area of 12.82 cm2 delivered a certified efficiency of 18.22%. This research will provide new ideas for fabrication of efficient inorganic perovskite solar modules in ambient condition.Highlights•Development of an ambient moisture induced chemical modification of CsPbI3 surface•Ability of in situ defect passivation and modulation of interfacial energy levels•Perovskite solar module with a certified aperture area efficiency of 18.22%SummaryHumidity 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 CsPbI3 perovskite. Herein, we report an environmental moisture-induced chemical passivation of the CsPbI3 perovskite surface by the hydrolysis of perfluorobutanesulfonyl chloride (PFSC). The in situ generated 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 situ surface-modified PFS-CsPbI3 perovskite solar modules with an aperture area of 12.82 cm2 deliver a state-of-the-art certified aperture area efficiency of 18.22%.Graphical abstract