Interactions between H2O and lead halide perovskites: Recent progress and applications

The synthesis of lead halide perovskites typically involves airborne H₂O molecules, which can exist in gaseous, liquid, or solid forms. Generally, H₂O is considered harmful to perovskite materials and devices, causing alarm at the mere mention of it. However, this pair of “old friends” always demonstrate a complex “love-hate” relationship. In some cases, H₂O can positively affect perovskites, endowing them with excellent properties. A comprehensive understanding of their interactions with H₂O will be crucial for the commercialization of perovskites. Here, we summarize recent progress on the interactions between H₂O and lead halide perovskites, focusing primarily on three areas: growth regulation, crystallization regulation, and interactions with already-formed perovskites. These interactions allow perovskites to be widely used in a variety of fields, including light-emitting diodes, solar cells, photodetectors, anti-counterfeiting, and bioimaging. Finally, we discuss the challenges and prospects of green synthesis, interfacial chemistry, and precursor solution chemistry.