Self-Powered and Broadband Photodetector with High Responsivity and Fast Response Based on La-Doped PbSe Film Heterojunction

PbSe is one of the most representative materials in lead chalcogenide semiconductors, possessing a narrow bandgap and demonstrating excellent absorption and photoresponse. However, undoped PbSe typically exhibits low carrier concentrations, along with large dielectric constants and thermal expansion coefficients, imposing limitations on its application in a high-performance photodetector. Doping is an effective strategy to overcome the inherent defects and enhance the optical and electrical properties. In this study, different compositions of Pb1−xLaxSe samples were obtained through solid-phase method doping with the rare earth element La. The doped Pb0.7La0.3Se showed superior optical and electrical properties and photoresponse. Additionally, based on the approach of constructing heterojunctions with thin films and two-dimensional (2D) materials, a self-powered p−n heterojunction photodetector, Pb0.7La0.3Se/WSe2, has been successfully fabricated. The device exhibited a continuous and stable light response from 405 to 1550 nm. Moreover, under 0 V bias and 650 nm laser irradiation, the device achieved the responsivity and specific detectivity of 22.85 A/W and 1.81 × 1012 Jones, along with a rapid response/recovery time (162/135 μs), demonstrating excellent photovoltaic effects and outstanding photodetection performance. The construction of heterojunctions with film and 2D materials provides a novel approach to achieving high-performance photodetectors. Simultaneously, the Pb0.7La0.3Se/WSe2 detector shows enormous potential in the field of superior photodetectors with a high on/off ratio, low noise, broadband, rapid response, and miniaturization.