Distinct moir\'e Exciton dynamics in WS2/ WSe2 heterostructure

TL;DR

This study uses time-resolved spectroscopy to investigate the dynamics of moiré excitons in a twisted WS2/WSe2 heterostructure, revealing their formation, decay, and strain effects relevant for optoelectronic applications.

Contribution

It provides new insights into the temporal behavior and spatial distribution of intralayer and interlayer moiré excitons in twisted heterostructures.

Findings

Interlayer moiré excitons form within a few picoseconds.

Interlayer excitons have a lifetime exceeding five nanoseconds.

Strain significantly affects moiré exciton behavior.

Abstract

This letter reports a time resolved pump-probe reflectance spectroscopic study on moir\'e excitons in a twisted monolayer WS2/WSe2 heterostructure. By probing at the resonant energies of intralayer excitons, we observed their distinct temporal tracks under the influence of interlayer excitons, which we attribute to the discrepancy in spatial distribution of the intralayer excitons in different layers. We also observed that intralayer moir\'e excitons in WSe2 layer differ at decay rate, which reflects different locations of Wannier-like and charge-transfer intralayer excitons in a moir\'e cell. We concluded that the interlayer moir\'e excitons form within a few picoseconds and have the lifetime exceeding five nanoseconds. Our results provide insights into the nature of moir\'e excitons and the strain's significant impact on their behaviour in twisted heterostructures, which could have important implications for the development of novel optoelectronic devices.