High‐Sensitive Ultrabroad Photodetector Based on PtSe ₂ /WSe ₂ /PtSe ₂ van der Waals Heterostructure

Abstract Photodetectors based on narrow bandgap two‐dimensional (2D) layered materials exhibited remarkable broadband detectivity, which brings the prospect of developing next‐generation photodetectors. However, uncooled long‐wave infrared (LWIR) photodetectors based on the narrow bandgap semiconductor with a low signal‐to‐noise ratio and high background noise level caused by the large dark current are severely restricted in practical application. Here, a metal electrode enhanced PtSe ₂ /WSe ₂ /PtSe ₂ (PWP) dual p‐n junctions is constructed using the large band offset between PtSe ₂ and WSe ₂ to depress the dark current. Benefiting from the extremely low dark current, the photodetector exhibits an ultra‐high light on/off ratio of ≈10 ⁷ . Notably, the PWP dual p‐n junction device demonstrated a fast response speed with a rising/decay ( τ _r / τ _d ) time of ≈4.2/2.9 µs and a competitive photovoltaic effect with a high energy conversion efficiency ( PCE ) of 5.6% in the visible spectral range. Moreover, the device exhibits excellent LWIR detection capability including high photoresponsivity ( R ) of ≈23.9 A W ⁻¹ and competitively specific detectivity ( D* ) of ≈1.6 × 10 ⁸ cm Hz ^1/2 W ⁻¹ . The work provides an effective strategy for designing a high‐performance wide spectral response photodetector.