Silicon photodiode-competitive 2D vertical photodetector

Abstract

Emerging two-dimensional (2D) materials offer significant potential for post-silicon photodetectors but often fall short of matching silicon photodiode performance. Here, we report a flexible, high-performance photodetector with a simple metal-2D semiconductor-metal structure by stacking Ti/WSe₂/Ag layers on a mica substrate. The device demonstrates a low dark current of 0.8 pA, high external quantum efficiency of 49%, a broad linear dynamic range of 86 dB, wide spectral sensitivity (350–1200 nm), and ultrafast response speed (~1 μs rise/fall time by conventional measurement and 337 ps via ultrafast photocurrent method). These advances originate from efficient photocarrier extraction via an ultrashort channel and Schottky barriers facilitated by van der Waals contacts. Additionally, the device’s ultrathin (~200 nm) profile ensures exceptional bending durability, while encapsulation protects against ambient degradation. Our strategy here will promote the development of the post-silicon photodetector and foster next-generation flexible optoelectronic applications.