Monolayer transition-metal dichalcogenides (TMDs) are direct-bandgap semiconductors. Their optical response is dominated by excitons, i.e., bound electron-hole pairs possessing large binding energies. These excitons interact strongly with light and give rise to various interesting optical and polaritonic phenomena. In addition, broken inversion symmetry and strong spin–orbit coupling in these materials yield unique optical selection rules and valley dependency, which can be addressed with circularly polarized light, providing valley-dependent exciton physics.

Altogether, these properties make monolayer TMDs an excellent platform for investigating light–matter interaction at the atomic scale. In our group, we study the properties of excitons in monolayer TMDs using various optical spectroscopy techniques at both room and cryogenic temperatures. The research combines fundamental studies of the physical response of TMD excitons and their practical usage as atomic-scale optoelectronic devices.