Precisely preparing lead iodide passivation layer for enhancing the performance of triple cation perovskite solar cells using krypton fluoride excimer laser

Precisely controlling the amount and location of PbI2 in a lead halide perovskite light absorption layer is crucial for improving the performance of perovskite solar cells (PSCs) by utilizing the passivation effect of PbI2. Based on the high absorption coefficient of perovskite materials and the resulting extremely shallow UV penetration depth, a non-contact approach of the precise preparation of a PbI2 passivation layer based on excimer laser irradiation (ELI) is proposed. 248 nm KrF excimer laser is adopted to irradiate the surface of [(FAPbI3)0.87(-MAPbBr3)0.13]0.92[CsPbI3]0.08 film, and a PbI2 passivation layer could be obtained on the surface of the triple cation perovskite film through the partial decomposition of the surface layer of perovskite films induced by ELI process. And then, the average power conversion efficiency of the PSCs has been increased obviously from 17.82% to 20.68%. This non-contact photonic approach successfully breaks through the bottleneck of precisely preparing PbI2 passivation layer and is expected to contribute to the further development of perovskite based devices.