Large Grains and Shallow Defect States by Early Crystal Growth Suppression for High Responsivity in Perovskite Photodetectors

The perovskite grain growth mechanism is a key factor to be considered for the enhancement of the photovoltaic effect in efficient self-powered perovskite photodetectors (PDs). Among processes employed in morphology engineering strategies, the washing process selectively removes polar solvents, induces nucleation, and promotes the formation of intermediate perovskite phases. In this study, by exploiting on the LaMer mechanism and Weimarn theory, the washing solvent in the washing process is controlled for large perovskite grains. Efficient photodetectors sensitive to a wide range of visible light are developed using a low-density washing solvent, namely ethyl ether, which maintains a low degree of nucleation and delays crystal growth leading to the expansion of perovskite grains. Perovskite processed with ethyl ether suppresses dark current and increases the photocurrent. Notably, the suppression of early crystal growth contributes to the enhancement of specific detectivity under self-powered operation. The proposed method for controlling nucleation and perovskite growth can be used to develop highly sensitive image sensors in smart vehicles via self-powered PDs due to reduction of fuel loss.