Observation of Inter-layer Excitons in MoSe2 Single Crystals

Interlayer excitons are observed coexisting with intralayer excitons in bi-layer, few-layer, and bulk MoSe2 single crystals by confocal reflection contrast spectroscopy. Quantitative analysis using the Dirac-Bloch-Equations provides unambiguous state assignment of all the measured resonances. The interlayer excitons in bilayer MoSe2 have a large binding energy of 153 meV, narrow linewidth of 20 meV, and their spectral weight is comparable to the commonly studied higher-order intralayer excitons. At the same time, the interlayer excitons are characterized by distinct transition energies and permanent dipole moments providing a promising high temperature and optically accessible platform for dipolar exciton physics.