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

Abstract The fabrication of van der Waals heterostructures (vdWHs) has drawn considerable interest because of their wide range of functionalities. Herein, a novel PdSe₂/ReSe₂ 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 × 10³) observed at gate voltage V_g = −60 V. The density functional theory calculations demonstrate the direct and indirect bandgap behavior of PdSe₂ and ReSe₂ in the monolayer structure, respectively. Additionally, the PdSe₂/ReSe₂ 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 × 10³ A W⁻¹, 4.05 × 10³, and 5 and 20 ms, respectively. Furthermore, the device exhibits a remarkable detectivity of ≈3.5 × 10¹² Jones. The findings hold great potential for advancing the fabrication of multifunctional vdW heterostructure devices.