Over 21% Efficient Cesium Lead Triiodide Solar Cell Enabled by Molten Salt Accelerating the Crystallization Processes.

High-quality CsPbI with low defect density is indispensable for acquiring excellent photoelectric performance. Meticulous regulation of the CsPbI crystal growth processes is both feasible and efficacious in enhancing the quality of perovskite films. In this study, the cesium formate (CsFo) is introduced.