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 x 10(-8) mA cm(-2) and 2 x 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.

Automated summary

By increasing the interfacial energy offset between the electron-blocking layer and the perovskite, the study demonstrates a photodiode with extremely low dark and noise currents, as well as high near-infrared sensitivity.