Various approaches to synthesize water-stable halide PeNCs

The "halide perovskite fever" is ongoing in material-based research due to the extraordinary properties of halide perovskites like high absorption coefficient, tunable band gap (throughout the visible range), near-unity emission quantum yield, large carrier diffusion length (exceeding 1 mu m), and a long recombination time (similar to mu s order). However, the water instability of halide perovskites is an Achilles' heel that must be overcome. Recently, some approaches have been adopted to improve the water stability of ABX(3) perovskites, including the substitution of A cations, ligand exchange, encapsulation in porous frameworks, passivation with inorganic or organic layers, and encapsulation in hydrophobic polymers and glass matrices. This review briefly introduces the degradation mechanisms according to the RH and summarizes various approaches to stabilize halide perovskites. An outlook for research directions of halide perovskites is also suggested.