Polarization splitting in polariton electroluminescence from an organic semiconductor microcavity with metallic reflectors

Organic semiconductors have received considerable attention as the active medium in microcavity devices that exploit the regime of strong exciton-photon coupling. The eigenstates of these systems are microcavity polaritons, whose properties are an admixture of the uncoupled exciton and photon. Organic microcavities are particularly interesting due to their large exciton binding energy which permits the electrical excitation of polaritons at room temperature. Measurements of electroluminescence are often facilitated through the use of metallic reflectors that form the optical microcavity and also serve as device electrodes. Here, we demonstrate that such structures exhibit a significant polarization splitting under both optical and electrical excitation. The size of the polarization splitting rivals those observed in strongly coupled microcavities based on distributed Bragg reflectors having a long optical penetration depth.