Influence of biaxial strain on the optoelectronic properties of Se-doped monolayer MoTe2

Abstract

In this paper, the effect of biaxial strain on the optoelectronic properties of Se-doped monolayer MoTe₂ (Se–MoTe₂) is systematically investigated using first-principles calculations based on density functional theory. The results demonstrate that the bandgap of the system increases from the intrinsic value of 1.049–1.064 eV upon substituting Te with Se while maintaining direct bandgap characteristics. The bandgap decreases significantly under biaxial tensile strain, with the system undergoing a semiconductor-to-metal transition at 12% tensile strain. Compressive strain induces a transition from direct to indirect bandgap and enhances charge transfer. Strain profoundly influences optical properties: Tensile strain causes red-shifted absorption and reflection peaks, increases the real part of the dielectric function, and elevates electron hopping probability. Conversely, compressive strain induces blue-shifted optical responses, with the absorption coefficient reaching a maximum value of 1.43 × 10⁵ cm⁻¹ at – 9% strain, accompanied by substantial light absorption enhancement. These findings establish a theoretical foundation for the material's applications in optoelectronic devices.

Graphical abstract