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arXiv · 1601.07351

Splitting between Bright and Dark excitons in Transition Metal Dichalcogenide Monolayers

J. P. Echeverry·B. Urbaszek·T. Amand·X. Marie·I. C. Gerber
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Abstract

The optical properties of transition metal dichalcogenide monolayers such as the two-dimensional semiconductors MoS$_2$ and WSe$_2$ are dominated by excitons, Coulomb bound electron-hole pairs. The light emission yield depends on whether the electron-hole transitions are optically allowed (bright) or forbidden (dark). By solving the Bethe Salpeter Equation on top of $GW$ wave functions in density functional theory calculations, we determine the sign and amplitude of the splitting between bright and dark exciton states. We evaluate the influence of the spin-orbit coupling on the optical spectra and clearly demonstrate the strong impact of the intra-valley Coulomb exchange term on the dark-bright exciton fine structure splitting.

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J. P. Echeverry, B. Urbaszek, T. Amand, X. Marie, I. C. Gerber. 2016-01-27. Splitting between Bright and Dark excitons in Transition Metal Dichalcogenide Monolayers. https://doi.org/10.1103/physrevb.93.121107

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