Polariton emission properties of an organic dye-doped polymer microcavity

Although organic polariton lasing has been recently demonstrated in dye-doped polymer microcavities, they only utilize the excitons and photons forming new emissive polaritonic states, often ignoring the strong and stable excimer emission that arises from dye aggregation at specific concentrations. The N,N′-bis(2-phenylethyl)-3,4,9,10-perylene dicarboximide (EP-PDI) dye-doped polymer showed stable and strong excimer emission at a specific concentration, with high PLQYs. In this study, we fabricated EP-PDI dye-doped polymer cavities with controlled cavity lengths (800 and 850 nm) and investigated the polariton emission properties. Within the cavities, we observe two types of cavity polariton emissions: the first is dominated by strong exciton-photon coupling with a Rabi splitting of 0.16 eV. Another polariton emission originates from the excimer radiative pumps. The radiatively pumping excimer populates the lower polariton state, with the decay profile reflecting the density of states. The excimer relaxation in the microcavity was faster than that of the pure film. The cavity polariton emission derived from the excimer state is sensitive to the cavity environment. The cavity length significantly affects the microcavity polariton emission wavelength and lifetime. Our findings highlight the importance of the microcavity length control in designing organic polaritonic devices, where excimer radiative pumps and polariton relaxation pathways critically influence performance.