Brightening of spin- and momentum-dark excitons in transition metal dichalcogenides

Abstract

Monolayer transition metal dichalcogenides (TMDs) have been in focus of current research, among others due to their remarkable exciton landscape consisting of bright and dark excitonic states. Although dark excitons are not directly visible in optical spectra, they have a large impact on exciton dynamics and hence their understanding is crucial for potential TMD-based applications. Here, we study brightening mechanisms of dark excitons via interaction with phonons and in-plane magnetic fields. We show clear signatures of momentum- and spin-dark excitons in WS${}_2$, WSe${}_2$ and MoS${}_2$, while the photoluminescence of MoSe${}_2$ is only determined by the bright exciton. In particular, we reveal the mechanism behind the brightening of states that are both spin- \textit{and} momentum-dark in MoS${}_2$. Our results are in good agreement with recent experiments and contribute to a better microscopic understanding of the exciton landscape in TMDs.

7 pages, 4 figures

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Cited by in corpus (11)

• Exciton optics, dynamics and transport in atomically thin semiconductors
• Strain-dependent exciton diffusion in transition metal dichalcogenides
• Optical dipole orientation of interlayer excitons in MoSe${}_2$-WSe${}_2$ heterostacks
• Interaction-driven transport of dark excitons in 2D semiconductors with phonon-mediated optical readout
• Phonon-assisted Exciton Dissociation in Transition Metal Dichalcogenides
• Probing Dark Excitons in Monolayer MoS${}_2$ by NonLinear Two-Photon Spectroscopy
• The effect of dielectric environment on the brightening of neutral and charged dark excitons in WSe${}_2$ monolayer
• Probing spin dynamics of 2D excitons with twisted light
• Magneto-Optics of Anisotropic Exciton Polaritons in Two-Dimensional Perovskites
• Hybrid dark excitons in monolayer ${MoS}_2$
• Brightening dark excitons and trions in systems with a Mexican-hat energy dispersion: example of InSe