Moiré exciton dynamics and moiré exciton-phonon interaction in a WSe${}_2$/MoSe${}_2$ heterobilayer

Abstract

Moiré patterns with angular mismatch in van der Waals heterostructures composed of atomically thin semiconducting materials are a fascinating platform to engineer the optically generated excitonic properties towards novel quantum phenomena. The moiré pattern as a periodic trap potential can give rise to spatially ordered zero-dimensional (0D) exciton ensembles, which offers the possibility for dense coherent quantum emitters and quantum simulation of many-body physics. The intriguing moiré exciton properties are affected by their dynamics and exciton-phonon interaction. However, the moiré exciton dynamics and the interaction between the moiré exciton and phonon are still elusive. Here, we report the moiré exciton and phonon interaction in a twisted WSe${}_2$/MoSe${}_2$ heterobilayer based on near-resonant photoluminescence excitation spectroscopy. We observed the selective excitation of the ground state of the moiré exciton at phonon resonance. The otherwise negligible small absorption below the continuum state is a hallmark of the density of states of a 0D-like system. In addition, the excitation power dependence of the PL spectra reveals the dynamics of moiré exciton ensembles between different potential minima with discrete energy levels via the resonant phonon scattering process. The results presented here of the moiré exciton dynamics under suppressed phonon interaction could pave a new way for the exploration of novel quantum phenomena of the moiré exciton towards potential applications in quantum optics.

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