Phonon-mediated exciton capture in Mo-based transition metal dichalcogenides

TL;DR

This paper investigates the ultrafast process of exciton capture in Mo-based transition metal dichalcogenides, revealing how phonons facilitate trapping of delocalized excitons into localized states, crucial for quantum photonics.

Contribution

It provides the first quantum kinetic analysis of exciton capture via phonons, elucidating the ultrafast dynamics and energy broadening mechanisms involved.

Findings

Efficient exciton capture occurs on an ultrafast timescale.

Polaron formation at low temperatures results in higher-energy excitons.

Interplay of acoustic and optical phonons broadens energy selection rules.

Abstract

Localized excitons play a vital role in the optical response of monolayers of transition metal dichalcogenides and can be exploited as single photon sources for quantum information technology. While the optical properties of such localized excitons are vastly studied, the ultrafast capture process of delocalized excitons into localized potentials is largely unexplored. We perform quantum kinetic calculations of exciton capture via acoustic and optical phonons showing that efficient capture takes place on an ultrafast time scale. The polaron formation in the low-temperature limit leads to higher-energy excitons which can then be efficiently trapped. We demonstrate that the interplay of acoustic and optical phonons leads to an efficient broadening of energy-selection rules. Our studies provide a deep understanding of the carrier trapping from two-dimensional materials into zero-dimensional potentials.