Enhanced performance of tin-based perovskite solar cells induced by an ammonium hypophosphite additive

As a promising lead-free perovskite candidate, tin-based halide perovskites such as FASnI(3) have attracted extensive attention recently in photovoltaic applications. However, the relatively low efficiency and poor long-term stability of tin-based perovskite solar cells hinder their practical applications. Here, ammonium hypophosphite is introduced into the FASnI(3) perovskite precursor to suppress the oxidation of Sn2+ and assist the growth of perovskite grains, leading to improved perovskite film quality and reduced defect density, and consequently, the device efficiency and open circuit voltage are substantially improved. More importantly, the solar cells exhibit pronounced enhancement of the long-term stability. This work provides a facile approach for improving the performance of tin-based perovskite solar cells by introducing ammonium hypophosphite as an antioxidant agent in the precursor solution.