The interplay between stacking order and exciton envelope functions for interlayer exciton formation in TMDC heterostructures

Transition metal dichalcogenide (TMDC) multilayer heterostructures host interlayer excitons that are long-lived because of their small electron-hole overlap. Due to their permanent out-of-plane electric dipole moment, interlayer excitons can be tuned into resonance and hybridize with optically bright intralayer excitons via external electric fields. The conversion of higher-energy intralayer excitons into interlayer excitons has been studied by considering the role of phonons and interlayer electronic hybridization. In this work, we study previously unreported selection rules for forming hybrid intralayer-interlayer exciton states directly from the spatial overlap of intralayer and interlayer excitons using a first-principles GW plus Bethe-Salpeter equation (GW-BSE) approach. We show that angular momentum arising from the local atomic registry may be transferred to the exciton envelope function, leading to novel exciton decay pathways that can be selected based on the external electric field. In particular, we predict stacking-dependent coupling between s-like and p-like exciton states, which was recently corroborated by experimental measurements.