When polarons meet polaritons: Exciton-vibration interactions in organic molecules strongly coupled to confined light fields

Abstract

We present a microscopic semi-analytical theory for the description of organic molecules interacting strongly with a cavity mode. Exciton-vibration coupling within the molecule and exciton-cavity interaction are treated on an equal footing by employing a temperature-dependent variational approach. The interplay between strong exciton-vibration coupling and strong exciton-cavity coupling gives rise to a hybrid ground state, which we refer to as the lower polaron polariton. Explicit expressions for the ground-state wave function, the zero-temperature quasiparticle weight of the lower polaron polariton, the photoluminescence line strength, and the mean number of vibrational quanta are obtained in terms of the optimal variational parameters. The dependence of these quantities upon the exciton-cavity coupling strength reveals that strong cavity coupling leads to an enhanced vibrational dressing of the cavity mode, and at the same time a vibrational decoupling of the dark excitons, which in turn results in a lower polaron polariton resembling a single-mode dressed bare lower polariton in the strong-coupling regime. Thermal effects on several observables are briefly discussed.

Tensor Network Simulation of Non-Markovian Dynamics in Organic Polaritons

“…A more detailed description of the theoretical approach can be found in [42,43]. We here focus on the time evolution after excitation, but note that the same approach also allows efficient calculation of the "lower polaron-polariton" [11,25,44,45], as shown in [43].…”

Molecular polaritons for controlling chemistry with quantum optics

“…Among these results, the development of the Holstein-Tavis-Cummings (HTC) model of vibronic polaritons [75,134] has been particularly useful, as it has been successfully used to explain features in the optical signals of organic microcavities that were notoriously confusing, such as the apparent breakdown of reciprocity in the oscillator strengths in absorption and emission strengths over specific frequencies [88,195]. Further predictions of the HTC model regarding the nature of the lower polariton manifold were later confirmed using variational techniques [196,197], and applied in subsequent work on singlet fission [198] and long-range energy transfer [158].…”

Strong Light–Matter Coupling as a New Tool for Molecular and Material Engineering: Quantum Approach

“…It is important to consider the vibronic structure to model fluorescence, while the effects of anharmonicity of the vibrational modes are also investigated under the strong coupling regime. The study of the interaction between photons, excitons, and vibrations is useful for understanding luminescence and light‐harvesting complexes . Advanced models predict more subtle effects such as differences between the emission and absorption rates from polaritons or contributions from polaritonic dark states .…”