Quasiparticle band gaps and optical spectra of strained monolayer transition-metal dichalcogenides

Employing the first-principles many-body perturbation theory, we report the excited-state properties, i.e., quasiparticle energy and excitonic effects, of strained monolayer 2H-phase transition-metal dichalcogenides, including MoS2, MoSe2, WS2, and WSe2. Beyond previous studies that considered uniaxial or biaxial strain, we cover arbitrarily axial strains and find complicated variations of quasiparticle band gaps, band-edge energies, direct-indirect gap transitions, and exciton energies. These results provide a complete picture for straining engineering of electronic structures and optical spectra of two-dimensional transition-metal dichalcogenides. Particularly, combined with high spatial-resolution optical measurements, our calculated results are essential for identifying local strain distribution and understanding the widely observed inhomogeneous free-carrier distributions and photoluminescence in realistic two-dimensional materials.