Vacuum Co‐Evaporation for High Reproducible and Environmentally Stable Hybrid Perovskite Thin Film Solar Cells by Cation Doping

Perovskite solar cells (PSCs) have attracted the attention of researchers due to their excellent photoelectric properties. Most of the PSCs are fabricated by the spin‐coating method, which is not conducive to the large‐scale reproducible fabrication of the device. In this work, a vacuum evaporation method is introduced to improve the process repeatability of preparing perovskite films. Furthermore, the environmental stability of PSCs is improved by depositing high‐quality and uniformly doped organic salt films on the crystal framework of lead iodide (PbI 2 ) by co‐evaporation method using phenylethylammonium iodide as the doping source. The optimized device achieves a champion power conversion efficiency of 17.79%. The remaining efficiency of the devices fabricated by the co‐evaporation method is 2.7 times higher than the counterparts fabricated by the solution method when stored at room temperature with humidity of 75%–85% for 90 h. It is attributed to the formation of a hydrophobic PEA‐based passivation layer at the grain boundaries, which leads to a stronger humidity stability of the devices.