Polaron-induced changes in moiré exciton propagation in twisted van der Waals heterostructures

Abstract

Twisted transition metal dichalcogenides (TMDs) present an intriguing platform for exploring excitons and their transport properties. By introducing a twist angle, a moiré superlattice forms, providing a spatially dependent exciton energy landscape. Based on a microscopic many-particle theory, we investigate in this work polaron-induced changes in exciton transport properties in the MoSe${}_2$/WSe${}_2$ heterostructure. We demonstrate that polaron formation and the associated enhancement of moiré excitonic mass lead to a significant band flattening. As a result, the hopping rate and the propagation velocity undergo noticeable temperature and twist-angle dependent changes. We predict a reduction of the hopping strength ranging from 80% at a twist angle of 1${}^{\circ }$ to 30% at 3${}^{\circ }$ at room temperature. The provided microscopic insights into the spatio-temporal exciton dynamics in presence of a moiré potential further deepens our understanding of the intriguing moiré exciton physics.