Fast Response Self-Powered UV–Vis–NIR Broadband Photodetector Based on a Type II Heterojunction of AgIn₅Se₈/FePSe₃

Ternary layered materials with small band gaps are prospective candidates for future UV–Vis–NIR broadband photodetectors, which show multiple degrees of freedom for tailoring their optoelectrical properties. AgIn5Se8 (AIS), with a direct bandgap (around 1.25 eV) and n-type conductivity, has great application potential in UV–Vis–NIR broadband optoelectronics due to its excellent light stability and high optical conductivity. However, research on AIS-based self-powered photodetectors with a broad spectrum and fast response speed is still rare. In this work, we report a self-powered photodetector based on a AgIn5Se8/FePSe3 (FPS) n–p heterojunction with a spectral detection range of 365–1020 nm. Benefiting from the built-in field, the type II heterojunction can suppress dark current and promote the rapid separation of electron–hole pairs. As a result, the fabricated photodetector exhibits a low dark current of 1 pA and a fast response time (τr/τd) of less than 20/20 ms. The results indicate that an AIS/FPS heterojunction proves to be an excellent candidate for broad spectrum, fast response, and self-powered photoelectronic devices.