Excitonic spectral features in strongly-coupled organic polaritons

TL;DR

This paper models the optical spectra of molecules in strongly-coupled organic microcavities, revealing how matter-light interactions can alter molecular states and produce temperature-dependent spectral features, with implications for understanding experimental observations.

Contribution

It introduces a microscopic model that accounts for self-consistent matter-light coupling effects, including vibrational degrees of freedom, explaining experimental spectral features in organic polaritons.

Findings

Matter-light coupling causes self-consistent changes in molecular states.

Temperature-dependent signatures are observed in the absorption spectrum.

Vibrationally dressed polaritons can explain experimental data.

Abstract

Starting from a microscopic model, we investigate the optical spectra of molecules in strongly-coupled organic microcavities examining how they might self-consistently adapt their coupling to light. We consider both rotational and vibrational degrees of freedom, focusing on features which can be seen in the peak in the center of the spectrum at the bare excitonic frequency. In both cases we find that the matter-light coupling can lead to a self-consistent change of the molecular states, with consequent temperature-dependent signatures in the absorption spectrum. However, for typical parameters, these effects are much too weak to explain recent measurements. We show that another mechanism which naturally arises from our model of vibrationally dressed polaritons has the right magnitude and temperature dependence to be at the origin of the observed data.