Solution-processed polariton microcavities: A novel platform to study organic optoelectronics through strong light-matter coupling

Modern organic optoelectronics relies on engineering device architectures that promote strong interactions between absorbers and electromagnetic fields. When the energy exchange rate between a material excitonic transitions and electromagnetic fields exceeds intrinsic losses, new hybrid light-matter states called polaritons form. Planar microcavity polaritons have shown promise in improving organic light-emitting diodes, photodiodes, and photovoltaics. However, traditional highly reflective microcavities require expensive and complicated energy intensive physical vapor deposition methods which limit their applications.
We present the first demonstration of a dielectric all-solution-processed polariton microcavity using Rhodamine 6G films in a poly(vinyl alcohol) matrix. This novel structure exhibits over 400 meV Rabi-splitting and photoluminescence with uniform dispersion along the lower polariton mode. Our innovative, fully automated deposition and annealing protocol prevents interlayer mixing which is crucial for fabricating high quality microcavities.
Our study highlights the significant impact of large Rabi splitting on molecular dynamics. In polariton microcavities with strong coupling, we observed a more than 10-fold increase in the critical excitation density for bimolecular annihilation compared to bare Rhodamine 6G films. This enhancement can only be partially attributed to the sub-3-fold measured enhancement in radiative lifetime, highlighting the critical role of strong coupling in the influence of molecular dynamics. These results indicate the critical role of large coupling strengths in modifying molecular interactions, potentially opening new avenues for enhancing the performance and efficiency of organic optoelectronic devices.