Asymmetrically flexoelectric gating effect of Janus transition-metal dichalcogenides and their sensor applications

High-performance nanodevices require fast and reversible tunability of electronic and optical properties under external stimuli. In the current work, using first-principles simulations and non-equilibrium Green function transport calculations, we demonstrate that bending can effectively and asymmetrically modulate the optoelectronic properties of Janus transition-metal dichalcogenides (J-TMDCs), due to their out-of-plane flexoelectric gating. The dynamic correlation of the electronic and optical behaviors is revealed by the bending-induced interplay between the quantum confined giant Stark effect and deformation potential. The nonsymmetric directional-information encoded in the concave and convex bending motions and the intrinsic dipole of the atomically thin film renders J-TMDCs promising for wearable motion sensors and chemical sensors.