Ultralow dark current in near-infrared perovskite photodiodes by reducing charge injection and interfacial charge generation

Metal halide perovskite photodiodes (PPDs) offer high responsivity and broad spectral sensitivity, making them attractive for low-cost visible and near-infrared sensing. A significant challenge in achieving high detectivity in PPDs is lowering the dark current density ( J D ) and noise current ( i n ). This is commonly accomplished using charge-blocking layers to reduce charge injection. By analyzing the temperature dependence of J D for lead-tin based PPDs with different bandgaps and electron-blocking layers (EBL), we demonstrate that while EBLs eliminate electron injection, they facilitate undesired thermal charge generation at the EBL-perovskite interface. The interfacial energy offset between the EBL and the perovskite determines the magnitude and activation energy of J D . By increasing this offset we realized a PPD with ultralow J D and i n of 5 × 10 −8 mA cm −2 and 2 × 10 −14 A Hz −1/2 , respectively, and wavelength sensitivity up to 1050 nm, establishing a new design principle to maximize detectivity in perovskite photodiodes. In lead‐tin halide perovskite photodiodes, the interfacial energy offset at the charge transport layer controls the dark current. In this work, by increasing this offset, the authors demonstrates a photodiode with ultralow dark and noise currents and high near‐infrared sensitivity.