Efficient All‐Vacuum Deposited Perovskite Solar Cells by Controlling Reagent Partial Pressure in High Vacuum

All-vacuum-deposited perovskite solar cells produced by controlling reagent partial pressure in high vacuum with newly developed multi-layer electron and hole transporting structures show outstanding power conversion efficiency of 17.6% and smooth, pinhole-free, micrometer-sized perovskite crystal grains.