Solvent‐Free MACl Post‐Treatment Using Close‐Spaced Sublimation Method for Dry‐Processed Perovskite Solar Cells

This study introduces a solvent‐free close‐spaced sublimation (CSS) method for both perovskite conversion and post‐treatment. A PbI 2 layer is deposited via thermal evaporation and subsequently converted into MAPbI 3 using CSS of Methylammonium iodide powder. The resulting MAPbI 3 layer is further passivated with MACl powder using the identical CSS method. Through this post‐treatment, it is possible to improve the quality of the perovskite layer, leading to a decrease of defect density and enhancing photovoltaic performances. As a result, device efficiency improves from 14.6% to 16.4%, with notable increases in J sc and V oc , along with a reduction in hysteresis. The potential of this solvent‐free CSS method is demonstrated, making it a promising approach for large‐scale manufacturing of perovskite and tandem solar cells.