Enhanced emission from interlayer excitons coupled to silicon nanodisk array

Van der Waals (vdW) heterostructures based on transition metal dichalcogenides (TMDs) generally possess a type-II band alignment that facilitates the formation of interlayer excitons (IEs) between constituent monolayers. Due to the spatially indirect property of interlayer excitons, the oscillator strength of it is of two orders of magnitude smaller than that of the intralayer excitons, resulting in a relatively low photoluminescence (PL) efficiency. Here, we achieve the PL enhancement of interlayer excitons across the entire heterostructure area at room temperature through introducing silicon nanodisk array. The significant enhancement mainly arises from the localized resonant electric field, which highly aligns with the out of plane (OP) interlayer excitons. Moreover, the silicon nanodisk array is demonstrated to greatly modify the far field emission properties of interlayer excitons to the surface normal direction, which further improves the PL intensity. The work contributes a novel method to control the emission of interlayer excitons in TMDs heterostructures to build efficient excitonic devices.