Doping Mechanism of Perovskite Films with PbCl₂ Prepared by Magnetron Sputtering for Enhanced Efficiency of Solar Cells

The last decade has witnessed a rapid growth of perovskite solar cells extended from mesoporous to planar architecture as well as from solution processing to solvent-free fabrication. The preparation of perovskite films by solvent-free method still presents significant challenges, such as the difficulty of film preparation by multiple evaporation sources in vapor deposition and the immaturity of the sputtered method. Here, we present a planar perovskite solar cell fabricated by solvent-free magnetron sputtering without the assistance of the mesoporous TiO2 layer, and lead chloride (PbCl2) was mechanically milled into the target of methylammonium lead halides (MAPbI3) to improve the quality of perovskite film by regulating the crystallization process with the Cl element. Furthermore, the internal reason for the effect of different PbCl2 doping contents on the trap density of perovskite films was also investigated in detail. These lead to an improved power conversion efficiency of planar heterojunction perovskite solar cells up to 17.10%, which is the highest efficiency recorded for the sputtered perovskite solar cells so far. The stability of resulting solar cells has also been significantly improved by exploring the doping mechanism of perovskite films with PbCl2 in detail, showing great research and application prospect.