Exciton energy transfer under low temperature in a lateral heteromonolayer of WSe2–MoSe2

Abstract

We examined the exciton energy transfer process in a lateral heteromonolayer of WSe2–MoSe2 at low temperature. Position-dependent photoluminescence (PL) and PL excitation spectroscopy measurements revealed the occurrence of exciton energy transport from WSe2 to MoSe2 both at RT and 15 K. The effective energy transport distance in WSe2 was longer at 15 K than at RT, suggesting that the dark excitons with longer diffusion length than bright excitons preferentially contributed to the exciton energy transport across the heterojunction interface at 15 K. Additionally, we observed that no valley information was transported from WSe2 to MoSe2 via the energy transfer process. This study provides useful insights for the development of excitonic devices based on exciton transport in transition metal dichalcogenides.