Unveiling Interface Interaction Assisted Broadband Photoresponse of Epitaxial 2D Bi2O2Se on Perovskite Oxides

Bi2O2Se has established itself as a revolutionary two-dimensional (2D) semiconductor owing to its superior electric, optoelectric and thermoelectric properties. The structural compatibility between Bi2O2Se and perovskite oxides makes the investigation of their heterointerfaces an intriguing frontier. Herein, we unveil the Bi2O2Se/SrTiO3 interfacial interaction by studying the photoresponse of the oxide heteroepitaxy. The record-broad photosensitivity (365–1850 nm) is ascribed to a complex interplay between photoconductive, photogating, pyroelectric and photo-thermoelectric (PTE) effects. The distinctive pyroelectricity, which results in a 900-fold decrease in the response time, originates from the surface polarization and relaxation at the Bi2O2Se/SrTiO3 interface. Self-powered behavior is reported for the first time in Bi2O2Se-based photodetectors. Under zero bias, the PTE-dominated photoresponse gives rise to a tunable polarity and magnitude of the photocurrent, and an estimated Seebeck coefficient of −127.8 μV K−1. The optimal photoresponsivity of 12.62 A W−1, external quantum efficiency of 1424.08% and detectivity of 1.51 × 109 Jones indicate the performance advancement of the photodiodes based on as-grown Bi2O2Se. Our study sheds light on the exploitation of exotic physical phenomena at the heterointerfaces between Bi2O2Se and perovskite oxides, and also indicates that 2D Bi2O2Se has a wide range of applications in piezoelectrics, ferroelectrics, self-powered nanogenerators and optical communications.