A New Strategy for Increasing the Efficiency of Inverted Perovskite Solar Cells to More than 21%: High‐Humidity Induced Self‐Passivation of Perovskite Films

The performance of perovskite solar cells (PSCs) is known to be extremely sensitive to humidity in the preparation environment. However, the main mechanism by which the moisture influences the quality of the perovskite film and the device performance is not yet fully understood. Herein, a new strategy is established to obtain inverted PSCs with a remarkabll high V OC by including a high‐humidity treatment and sufficient DMSO‐atmosphere annealing in the preparation process. It is found that the lattice distortion on the surface of perovskite grains caused by the high‐humidity treatment plays a key role in the self‐passivation of perovskite. Inverted (p‐i‐n) PSCs based on the self‐passivated perovskite films show effective suppression of nonradiative recombination, which increase the device V OC to 1.17 V and achieve the highest efficiency of 21.38%. It is expected that the findings of this work shed more light on the currently proposed mechanism governing the action of moisture on the performance of the PSCs.