Proximity-induced moiré exciton in a transition metal dichalcogenide monolayer

Moiré patterns in two-dimensional materials, formed due to a lattice mismatch or a relative rotation between the layers, have gained research interest as a platform to study exotic electronic and excitonic phases. The moiré potential responsible for the emergent phenomena is induced by the atomic reconstructions and the variation of interlayer interaction upon creating a moiré pattern. Using first-principles calculations, we explore a noninvasive way to induce a spatially varying moiré potential in the target monolayer transition metal dichalcogenide (TMD) by placing it on another multilayer material with domains of alternative electric polarization, for example, a parallel-stacked bilayer hexagonal boron nitride with a small interlayer twist. Our first-principles calculations reveal novel excitons with spatial localization and excited-state series that differ from those possible in regular stackings of twisted bilayer TMDs and suggest an experimental route for the engineering of tunable moiré potential post material synthesis.