All-Inorganic Halide Perovskites for Optoelectronics: Progress and Prospects

During the past 8 years, solution-processed organic–inorganic metal halide (OMH) perovskites have become some of the most notable materials because they can exhibit high solar cell efficiency, exceeding 20%. However, due to the volatile and hygroscopic nature of the organic cations, OMH perovskites suffer from chemical instability, especially at high temperatures. Therefore, all-inorganic metal halide (IMH) perovskites (CsBX₃, B = Pb, Sn, Ge; X = Cl, Br, I) are rapidly emerging as promising alternatives because of their superior stabilities and comparable properties, such as strong emission, high fluorescence quantum yield and tunable bandgap covering entire visible spectrum. Highlighted by these advantages, IMH perovskites have attracted enormous attention, indicating a promising future. In this review, the recent progress on the syntheses of IMH perovskites is outlined. In addition, the research development of IMH perovskites in optoelectronic devices, such as perovskite solar cells, photodetectors, and light-emitting diodes, is introduced. Finally, the challenges facing the field of IMH perovskites are discussed and some possible solutions based on the available literature are suggested.