Efficient MAPbI₃-based perovskite solar cells exceeding 21% efficiency via aging treatment

Recently, the demand for large-area and high-efficiency perovskite solar cells (PSCs) has increased, and a twostep process for high-efficiency large-area PSCs is actively being studied. However, the two-step process is still less efficient than the one-step antisolvent dripping process owing to the poor interdiffusion of organic components. In this study, a perovskite layer using a hybrid deposition method in which an excess of methylammonium iodide (MAI) solution is reacted with thermally evaporated PbI2 is reported. The perovskite film quality is improved by reacting unreacted residual PbI2 with excess MAI by applying daily electrical stress and aging for 60 days in a glovebox. The best PSC exhibits a PCE of 21.1 %, the highest reported power conversion efficiency among PSCs based on the two-step hybrid deposited MAPbI3 perovskite, with a large enhanced opencircuit voltage of 1.21 V and fill factor of 80.8 %. Moreover, using the solvent pre-heat treatment method, the reaction of unreacted PbI2 with MAI is accelerated, and the aging time of PSCs is shortened from 60 to 7 days, showing a PCE value of 20.7 %. Furthermore, we present a large-area PSC with a PCE of 19.4 %, indicating that the PCE can be improved through the hybrid deposition method.