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.