Strong exciton-photon coupling and exciton hybridization in a thermally evaporated polycrystalline film of an organic small molecule

We demonstrate strong exciton-photon coupling in an optical microcavity containing a thermally evaporated polycrystalline organic thin film. Microcavity polaritons result from coupling between the 0-0 excitonic transition of 3,4,7,8 napthalenetetracarboxylic dianhydride and a cavity photon. For thicker films, the 0-1 transition also couples to the cavity mode, as vibronic relaxation is overcome by the short Rabi period for strong coupling. To our knowledge, this is the first report of strong coupling between a cavity photon and multiple vibronic transitions in a single material, made possible by the pronounced vibronic absorption features characteristic of crystalline organic materials.