High detectivity UV-visible-NIR broadband perovskite photodetector using Pb-Sn mixed narrow-gap absorber and NiOx electron blocker

Halide perovskites are very attractive for solution-processed visible and near-IR sensing applications due to their intrinsic advantages such as excellent photosensitivity, bandgap tunability, broadband sensitivity, high charge transport capability, and solution-processability. Unlike Pb-based perovskites, which cannot be tuned to below 1.48 eV, Pb-Sn mixed halide perovskites exhibit low bandgaps of 1.2-1.3 eV. Due to the low bandgap, these Pb-Sn mixed halide perovskite can absorb light till 1000nm making them a viable alternative to Silicon as the visible and near-IR broadband photodetectors. However, the low-bandgap nature of Pb-Sn mixed perovskites also causes large levels of electron and hole injection from anode and cathode, thus leading to high dark current. To mitigate the issue of charge injection, therefore, it is important to have an electron blocking layer (EBL) and a hole blocking layer (HBL) inserted between the electrodes and the Pb-Sn mixed perovskite photodetectors.