Scalable solution-phase processing of halide perovskite films: Solvent removal, quenching methods, and film drying

Solution-based processes are attractive for industrial and large-scale production of thin films of halide perovskites, which are highly promising semiconductor materials for high-performance optoelectronic devices. The film formation process after the solution coating or printing is complex and starts with solvent removal which triggers the crystallization of the perovskite phase. Before the crystallization onset, the solvent continual removal causes the wet film drying or chemical changes that lead to a supersaturated system or a stabilized intermediate structure which subsequently transforms into the targeted perovskite phase. As such, the kinetics of solvent removal and film drying greatly influences the morphology and microstructure of solution-processed perovskite films. Scalable solution deposition processes generally form thick wet films with high solvent contents, which need to be controlled to obtain desired properties. This review describes the formation of perovskite films from scalable processes, with a special focus on the interplay between solvent removal and film solidification. The understanding of chemical and physical processes taking place as the forming film undergoes a range of transitions is discussed. In addition, the control strategies of solvent removal to rapidly induce supersaturation in scalable processes are reviewed along with the reasons behind irregularities formation in large-area films. Furthermore, different predictive models describing the kinetics of changes in dying films of perovskites are also examined. By overviewing the state of research on scalable processing, the review aims to suggest potential research directions that could lead to further progress in the field.