Long-Range Exciton Energy Transfer in Two-Dimensional Materials

Abstract

Excitons – bound electron–hole pairs – are central to the optical properties of semiconducting van der Waals materials, offering a platform for exploring strong light-matter interactions, Bose-Einstein condensation, superradiance, nanolasing, and energy harvesting applications. While strong exciton–photon coupling is typically realized using high-quality optical cavities, such architectures often limit scalability and integration with van der Waals heterostructures and photonic circuitry. In this review, we focus on emerging pathways for coherent exciton energy transfer that circumvent these limitations. Specifically, we examine two classes of self-sustained hybrid light-matter states: self-hybridized exciton–polaritons, which arise from intrinsic excitonic interactions with photons in layered materials, and plasmon-enhanced exciton–polaritons (or plexcitons), enabled by strong coupling between excitons and plasmon polaritons or Bloch plasmon waves. We discuss key experimental approaches, including electron beam excitation, far-field optical spectroscopy, and scanning-probe techniques, that allow the direct observation of Fabry-Pérot resonances, guided polariton modes, and their propagation and dephasing dynamics. Furthermore, we provide a broader overview on exciton energy transfer, contrasting incoherent diffusion with coherent, delocalized transfer mechanisms. Finally, we highlight design strategies and material platforms that are paving the way toward long-range, room-temperature coherent exciton transport in van der Waals systems, with implications for quantum optics, integrated photonics, and excitonic circuitry.