Distinct moiré exciton dynamics in WS2/WSe2 heterostructure

Abstract

<p>This letter reports a time resolved pump-probe reflectance spectroscopic study on moiré 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 moiré excitons in WSe2 layer differ at decay rate, which reflects different locations of Wannier-like and charge-transfer intralayer excitons in a moiré cell. We concluded that the interlayer moiré excitons form within a few picoseconds and have the lifetime exceeding five nanoseconds. Our results provide insights into the nature of moiré 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.</p>