Abstract

We present a comprehensive theoretical investigation of the excitonic properties of uni-axially strained transition-metal dichalcogenide monolayers by solving the Bethe-Salpeter equation in the Wannier tight-binding scheme established on the basis of first-principles. The presence of an uni-axial strain in a MoS₂ monolayer is shown to impact most the spin-forbidden exciton states, including gray and dark excitons. As a consequence of strain-induced valley drift and electron-hole exchange interaction, imposing uni-axial strain onto a MoS₂ monolayer dramatically reshapes the band dispersion of dark excitons from a parabola to a Mexican-hat-like profile, accompanying unusual sign-reversal of the exciton effective mass and slight strain-activated brightness. The studies further predict strain-induced diversification of exciton diffusivities, transition dipoles, and angle-resolved optical patterns of bright, gray, and dark excitons in uni-axially strained TMD monolayers.

Abstract

We present a comprehensive theoretical investigation of the excitonic properties of uni-axially strained transition-metal dichalcogenide monolayers by solving the Bethe-Salpeter equation in the Wannier tight-binding scheme established on the basis of first-principles. The presence of an uni-axial strain in a MoS₂ monolayer is shown to impact most the spin-forbidden exciton states, including gray and dark excitons. As a consequence of strain-induced valley drift and electron-hole exchange interaction, imposing uni-axial strain onto a MoS₂ monolayer dramatically reshapes the band dispersion of dark excitons from a parabola to a Mexican-hat-like profile, accompanying unusual sign-reversal of the exciton effective mass and slight strain-activated brightness. The studies further predict strain-induced diversification of exciton diffusivities, transition dipoles, and angle-resolved optical patterns of bright, gray, and dark excitons in uni-axially strained TMD monolayers.

Abstract

We present a comprehensive theoretical investigation of the excitonic properties of uni-axially strained transition-metal dichalcogenide monolayers by solving the Bethe-Salpeter equation in the Wannier tight-binding scheme established on the basis of first-principles. The presence of an uni-axial strain in a MoS₂ monolayer is shown to impact most the spin-forbidden exciton states, including gray and dark excitons. As a consequence of strain-induced valley drift and electron-hole exchange interaction, imposing uni-axial strain onto a MoS₂ monolayer dramatically reshapes the band dispersion of dark excitons from a parabola to a Mexican-hat-like profile, accompanying unusual sign-reversal of the exciton effective mass and slight strain-activated brightness. The studies further predict strain-induced diversification of exciton diffusivities, transition dipoles, and angle-resolved optical patterns of bright, gray, and dark excitons in uni-axially strained TMD monolayers.

Abstract

We present a comprehensive theoretical investigation of the excitonic properties of uni-axially strained transition-metal dichalcogenide monolayers by solving the Bethe-Salpeter equation in the Wannier tight-binding scheme established on the basis of first-principles. The presence of an uni-axial strain in a MoS₂ monolayer is shown to impact most the spin-forbidden exciton states, including gray and dark excitons. As a consequence of strain-induced valley drift and electron-hole exchange interaction, imposing uni-axial strain onto a MoS₂ monolayer dramatically reshapes the band dispersion of dark excitons from a parabola to a Mexican-hat-like profile, accompanying unusual sign-reversal of the exciton effective mass and slight strain-activated brightness. The studies further predict strain-induced diversification of exciton diffusivities, transition dipoles, and angle-resolved optical patterns of bright, gray, and dark excitons in uni-axially strained TMD monolayers.