Low efficiency of the exciton-phonon scattering involving large momentum transfer in 2D-TMDC*

Atomically thin transition metal dichalcogenide sheets are among the most promising systems for efficiently controlled emission of quantum light. However, like in all solid-state based emitters, temperature is a critical parameter to have into account, because of the ever present decoherence induced by phonons.
In this theoretical work, the effects of the transferred momentum on the exciton-phonon interaction is studied. As a main result, the inefficiency of this coupling for scattering involving large phonon momentum is found, as consequence of the localization of the exciton wave function in the reciprocal space.
This feature may favor robustness of the high quality optical activity of these low dimensional systems, along significant temperature ranges.