Layer-dependent excitonic valley polarization properties in MoS₂–WS₂ heterostructures

Abstract

In this work, we investigate the polarization of the excitonics valley in MoS 2 –WS 2 heterostructures using circular polarization-resolved photoluminescence. The valley polarization is the largest (≈28.45%) in the 1L–1L MoS 2 –WS 2 heterostructure and the polarizability of A W S 2 decreases as the number of WS 2 layers increases. We further observed a redshift of exciton X Mo S 2 − in MoS 2 –WS 2 heterostructures with the increase of WS 2 layers, which is attributed to the displacement of the MoS 2 band edge, indicating the layer-sensitive optical properties of the MoS 2 –WS 2 heterostructure. Our findings shed light on the understanding of exciton behavior in multilayer MoS 2 –WS 2 heterostructures that may promote their potential applications in optoelectronic devices.