Microcavity-like exciton-polaritons can be the primary photoexcitation in bare organic semiconductors.
Strong-coupling between excitons and confined photonic modes can lead to the formation of new quasi-particles termed exciton-polaritons which can display a range of interesting properties such as super-fluidity, ultrafast transport and Bose-Einstein condensation. Strong-coupling typically occurs when an excitonic material is confided in a dielectric or plasmonic microcavity. Here, we show polaritons can form at room temperature in a range of chemically diverse, organic semiconductor thin films, despite the absence of an external cavity. We find evidence of strong light-matter coupling via angle-dependent peak splittings in the reflectivity spectra of the materials and emission from collective polariton states. We additionally show exciton-polaritons are the primary photoexcitation in these organic materials by directly imaging their ultrafast (5 × 106 m s-1), ultralong (~270 nm) transport. These results open-up new fundamental physics and could enable a new generation of organic optoelectronic and light harvesting devices based on cavity-free exciton-polaritons.
Online Publication Date
European Research Council (758826)
Engineering and Physical Sciences Research Council (EP/L027151/1)
European Commission Horizon 2020 (H2020) ERC (883703)
Royal Commission for the Exhibition of 1851 (RF499/2018)
European Research Council (639088)
European Research Council (670405)