Solution-processed lead halide perovskite films for application in perovskite solar cells: from coating methods to growth dynamics

After 15 years of development, perovskite solar cells have achieved a certified efficiency of >26%, offering one of the most reliable solutions for green energy. This progress should be ascribed to the excellent optoelectronic properties of metal halide perovskite film, for example, the excellent extinction behavior and the long diffusion length of charge carriers. Basically, these properties rely on the crystallization quality. In recent years, many methods have been developed to grow uniform and well-crystallized perovskite films, such as one-step and two-step solution-based methods, and evaporation methods. These methods help to grow films with areas ranging from several to hundreds of square centimeters. For each method, regulating the growth dynamics of perovskites has remained as one of the main tasks. Here, in this review, we discuss the coarsening dynamics of lead halide perovskites when using the solution-based methods, such as one-step or two-step spincoating, and bladecoating. Strategies such as component engineering, solvent engineering and additive engineering are briefly introduced and discussed. Finally, some perspectives are given.