Tuning of MoS₂ Photoluminescence in Heterostructures with CrSBr

Monolayers of semiconducting transition metal dichalcogenides (TMDCs) are known for their unique excitonic photoluminescence (PL), which can be tuned by interfacing them with other materials. However, integrating TMDCs into van der Waals heterostructures often results in a significant quenching of the PL because of an increased rate of nonradiative recombination processes. We demonstrate a wide-range tuning of the PL intensity of monolayer MoS₂ interfaced with another layered semiconductor, CrSBr. We discover that a thin CrSBr up to ≈20 nm in thickness enhances the PL of MoS₂, while a thicker material causes PL quenching, which is associated with changes in the excitonic makeup driven by the charge redistribution in the CrSBr/MoS₂ heterostructure. Transport measurements, Kelvin probe force microscopy, and first-principles calculations indicate that this charge redistribution most likely causes n- to p-type doping transition of MoS₂ upon contact with CrSBr, facilitated by the type II band alignment and the tendency of CrSBr to act as an electron sink. Furthermore, we fabricate an efficient AC-regime photodetector with a responsivity of 10⁵ A/W from a MoS₂/CrSBr heterostructure.