Dissecting exciton-polariton transport in organic molecular crystals: Emerging conductivity assisted by intermolecular vibrational coupling

In this work, we systematically investigate the spectral and transport properties of exciton-polaritons under the explicit influence of intermolecular vibrational coupling, which introduces dynamic disorder. In the context of a one-dimensional molecular chain strongly interacting with a cavity photon, we demonstrate the polaritonic characteristics of the spectral function and its interactions with the electronic band broadened by the coupling disorder. We further dissect the current flux into its bare exciton contribution and transport via the cavity photon. Our results reveal that the enhancement in the exciton-polariton mobility and frequency-resolved conductivity stems from the photon-mediated current. More importantly, contrary to the intuition that dynamic disorder hinders transport, intermolecular vibrational coupling can facilitate exciton-polariton transport, offering an additional degree of tunability for material properties.