Intrinsic dipolar excitons and superdiffusive transport in rhombohedral MoS₂ bilayers

Excitons offer a charge-free means of energy transport, yet their electrical neutrality limits external control. Dipolar excitons, formed when electrons and holes are spatially separated, enable electric-field manipulation and strong dipole interactions. While such excitons have been studied in van der Waals heterostructures where electrons and holes occupy different layers, we show that rhombohedral (3R) stacked MoS₂ bilayers provide an intrinsic platform for realizing them, owing to the built-in polarization from broken inversion symmetry. Using transient absorption spectroscopy, we compare excitonic dynamics in monolayer, bilayer, and bulk MoS₂ exfoliated from hexagonal (2H) and 3R crystals. Monolayers from 3R and 2H crystals show similar lifetimes, whereas the 3R bilayer exhibits a longer lifetime, indicating reduced electron–hole overlap. Moreover, transient absorption microscopy reveals rapid, superdiffusive transport of dipolar excitons in 3R bilayers, distinct from the diffusive behavior in 2H and monolayer samples. These results highlight how intrinsic dipole fields in 3R MoS₂ govern exciton lifetime and mobility.