Evidence of Polaritonic Intensity Borrowing in a Strongly Coupled Metalloporphyin-Cavity System*

The strong coupling of cavity photons to the frontier molecular electrons leads to the formation of delocalized cavity polariton states. These delocalized, hybrid light-matter excitations enable novel mechanisms to control energy and charge transfer. While most of the focus on polariton formation deals with mechanistic understanding of how strong light-molecule coupling leverages photonic character to affect molecules, much less effort has been put into understanding how molecular properties can impact polaritonic behavior. Using a simple three level, Tavis-Cummings model, we show vibronic coupling between the B and Q states of a molecule like copper (II) tetratephenyl porphyrin (CuTPP) drives formation of a weakly dispersive, Q-like state. We fabricated and characterized single and multilayer cavity polariton samples using CuTPP and find the PL spectra of these samples in the region near the moleculess Q fluorescence contains light emission peaks consistent with the predictions of our simple theory. We consider explanations of the variations in the peak characteristics in different multilayer samples. Our results demonstrate how one can use the intrinsic properties of molecules to enable the formation of novel, light-like states and multi-mode photon-photon interactions in cavity polariton samples.