Tuning Interlayer Coupling in Large-Area Heterostructures with CVD-Grown MoS₂ and WS₂ Monolayers

TLDR

Band offsets between monolayer transition metal dichalcogenides can efficiently separate charge carriers or rectify charge flow, enabling atomically thin devices and exotic 2D physics, but large‑area heterostructures are limited by synthesis and interlayer coupling challenges. The study demonstrates large‑area (>tens of micrometers) heterostructures of CVD‑grown WS₂ and MoS₂ monolayers with externally tunable interlayer coupling. CVD‑grown WS₂ and MoS₂ monolayers were assembled into heterostructures whose interlayer interaction was externally tuned from non‑coupling to strong coupling. The tunable interlayer coupling causes the heterostructure’s luminescence spectrum to shift from additive layer‑specific peaks to a new profile governed by charge transfer and band alignment, opening avenues for novel material systems with rich functionalities and physical effects.

Abstract

Band offsets between different monolayer transition metal dichalcogenides are expected to efficiently separate charge carriers or rectify charge flow, offering a mechanism for designing atomically thin devices and probing exotic two-dimensional physics. However, developing such large-area heterostructures has been hampered by challenges in synthesis of monolayers and effectively coupling neighboring layers. Here, we demonstrate large-area (>tens of micrometers) heterostructures of CVD-grown WS2 and MoS2 monolayers, where the interlayer interaction is externally tuned from noncoupling to strong coupling. Following this trend, the luminescence spectrum of the heterostructures evolves from an additive line profile where each layer contributes independently to a new profile that is dictated by charge transfer and band normalization between the WS2 and MoS2 layers. These results and findings open up venues to creating new material systems with rich functionalities and novel physical effects.