First-principles study on the effects of combined tensile and bending strain on electronic structure of doped and defective MoS 2

Abstract In this work, the regulatory effects of combined tensile and bending strain on the electronic structure of monolayer intrinsic MoS 2 , oxygen-doped MoS 2 , and MoS 2 with sulfur vacancy, molybdenum vacancy, and combined sulfur–molybdenum vacancies are systematically investigated using first-principles calculations. The results demonstrate that oxygen doping enhances the structural stability of MoS 2 , whereas vacancy defects reduce it, with molybdenum vacancy exerting a more pronounced destabilizing effect. Under combined strain, the binding energies of all systems become less negative, indicating a gradual reduction in stability. Notably, the MoS 2 +3O-S system exhibits the largest binding energy increase (0.778%), while intrinsic MoS 2 shows a comparatively smaller increase (0.626%). From an electronic perspective, combined strain weakens the covalent character of Mo–S σ bonds while enhancing strain-sensitive π-type interactions, thereby promoting the hybridization and broadening of localized electronic states introduced by oxygen doping and vacancy defects. As a consequence, the band gap decreases monotonically with increasing strain. In systems containing molybdenum vacancy, enhanced covalency in O–Mo bonds leads to exceptionally strong electronic tunability. Under a combined strain of ε = 5% and θ = 25°, the band gap of the MoS 2 +3O-Mo system is reduced to 0.071 eV, indicating a transition toward a semi-metallic state. This study reveals the atomic-scale mechanisms underlying the coordinated regulation of electronic properties through strain, doping, and defects in two-dimensional MoS 2 , providing a solid theoretical foundation for the design of tunable optoelectronic devices and strain-sensitive functional materials.