Intermediate Chemistry of Halide Perovskites: Origin, Evolution, and Application.

The preparation of solution-processed metal halide perovskites is interwoven with research on their intermediate chemistry. In this Perspective, molecule-level insights are provided into how Lewis base additives (LBAs), , DMSO and NMP, facilitate powder-to-film formation processes (, the chemical origin of intermediate structures, structural evolution of intermediate-to-perovskite phase transition, and device-based application of intermediate-evolved perovskites). LBAs interact with Lewis acid species (cationic A or B sites) of ABX structures with separate probability in terms of coordination bonds or hydrogen bonds to form two types of intermediate structures, inducing significant differences within intermediate-to-perovskite processes. In addition, in-depth understanding of intermediate chemistry favors the multifaceted applications of solution-processed perovskites. A brief summary is finally provided together with a perspective on how intermediate chemistry determines perovskite properties and applications.