Recent progress on all-inorganic metal halide perovskite solar cells

Metal halide perovskites have attracted tremendous interest because of their unique properties. Among these materials, organic–inorganic metal halide perovskite solar cells (PSCs) exhibit a rapid development with the power conversion efficiency (PCE) increased from initially 3.8% to nowadays 25.5%. However, the inherent chemical instability of organic–inorganic metal halide perovskite materials against moisture, heat, and ultraviolet light hinders their commercialization. Therefore, by replacing organic cations with inorganic cations, all-inorganic metal halide (IMH) PSCs are regarded as promising alternatives, and their PCEs have exceeded 20% since the first report in 2015. In this review, we discuss the latest progress of IMH perovskites and their applications in solar cells, which is followed by a summary of existent challenges in the IMH-PSC field and an outlook on future development.