Photodetection Enhancement of PdSe₂/ReSe₂ Van der Waals Heterostructure Field‐Effect Transistors: A Density Functional Theory‐Guided Approach

The fabrication of van der Waals heterostructures (vdWHs) has drawn considerable interest because of their wide range of functionalities. Herein, a novel PdSe 2 /ReSe 2 vdWHs with gate‐tunable rectification behavior and excellent broadband photodetection characteristics is presented. The application of the gate bias substantially enhances the rectification behavior, with the highest rectification ratio (≈3.13 × 10 3 ) observed at gate voltage V g = −60 V. The density functional theory calculations demonstrate the direct and indirect bandgap behavior of PdSe 2 and ReSe 2 in the monolayer structure, respectively. Additionally, the PdSe 2 /ReSe 2 heterojunction displays a strong photo‐response in the near‐infrared region and achieves a high photoresponsivity, an excellent external quantum efficiency, and rapid rise and decay times of 1.7 × 10 3 A W −1 , 4.05 × 10 3 , and 5 and 20 ms, respectively. Furthermore, the device exhibits a remarkable detectivity of ≈3.5 × 10 12 Jones. The findings hold great potential for advancing the fabrication of multifunctional vdW heterostructure devices.