Strain-Tunable Ultrastable MoS₂/Fluorographene Hybrid Photodetectors of High Responsivity

Abstract

Strained silicon technology for electronics is proven as a successful method for low-power devices. Extending this concept to two-dimensional (2D) semiconductors of transition-metal dichalcogenides such as MoS2 monolayer-based devices brings added advantages of mechanical flexibility, layer-dependent tunability, etc., to the devices. Moreover, the possibility of bringing synergistic effects via 2D heterostructure formation is an added benefit of such devices, while the stability of such devices is in question. Here, we demonstrate the possibilities of the development of fluorographene–MoS2 heterostructure-based strain-tunable photodetectors of high chemical stability and photodetectivity. This heterostructure photodetector made on a flexible poly(ethylene terephthalate) substrate exhibits a consistent photocurrent enhancement toward the applied strain with a broad range of spectral response (350–850 nm), having a high gauge factor of ∼1400. Studies using density functional theory-based calculations indicate the possibilities of band-gap modification from 400 to 90 meV with the applied strain ranging from 0 to 4%, along with strain-dependent charge transfer among the layers. Moreover, ab initio molecular dynamics calculations at 400 K under a 4% strain indicate the structural stability of the heterostructure, ensuring the robustness of the present device architecture.