A Self‐Powered Photodetector Based on Graphene Enhanced WSe2/PtSe2 Heterodiode with Fast Speed and Broadband Response

Abstract Narrow bandgap 2D layered material platinum selenide (PtSe 2 ) with good environmental stability, high carrier mobility, and high light absorption, has been widely investigated for uncooled midwave‐infrared (MWIR) photodetection. However, the phototransistor based on the PtSe 2 operation at room temperature suffered from the high dark current and background noise. Here, a graphene (G)‐enhanced G‐WSe 2 /PtSe 2 hetero‐diode placed on a metal electrode is reported. To enhance the photogain, a graphene layer placed on the WSe 2 /PtSe 2 heterodiode as a local gating layer is designed. The device exhibits an ultra‐high light on/off ratio of up to 10 8 and ultra‐fast photoresponse speed with raising time τ r = 0.9 µs and decay time of τ d = 1.5 µs in the visible spectra range. Notably, ultrabroad band photoresponse from 405 to 3366 nm is demonstrated under the self‐power model. Notably, the device presented a competitive photovoltaic effect with a high energy conversion efficiency (PCE) of 3.45%. The results pave the way toward a new approach to tuning the performance of the atomic thin layered materials photodetector.