Abstract
The optical properties of transition metal dichalcogenide monolayers such as the two-dimensional semiconductors and 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 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.
- Received 27 January 2016
- Revised 1 March 2016
DOI:https://doi.org/10.1103/PhysRevB.93.121107
©2016 American Physical Society