Polariton Mediated Electron Transfer under the Collective Molecule-Cavity Coupling Regime

We investigate polariton-mediated electron transfer (PMET) under the collective molecule-cavity coupling regime, with the presence of dark state transfer, cavity loss, and continuous-wave (CW) laser driving using quantum dynamics simulations and analytic rate constant theories. We demonstrate how the PMET rate constant can be enhanced by the collective coupling effect, that is, light-matter coupling strength is small, but there are many molecules collectively coupled to the cavity. We demonstrate how the delocalized light-matter interactions, together with the local electronic donor-acceptor couplings can be used to enhance the rate constant of the charge transfer reactions. We further show that the PMET rate constant is affected by dark states and cavity loss which are often regarded as obstacles, and how to overcome them to provide a significant cavity-induced rate constant enhancement under the collective coupling regime. We first show how reactions initialized in the collective upper polariton (UP) state can significantly enhance the PMET rate constant by increasing the reaction driving force of an otherwise uphill ET reaction with collective strong coupling and positive detuning. We then show that by driving the UP state with a CW laser in a positively detuned cavity, the effective PMET rate constant can be several orders of magnitude larger than outside the cavity even with significant molecular disorder and cavity loss. These results reveal a promising approach to realize photochemical rate enhancement with collective strong coupling in disordered and lossy polariton systems as well as enable otherwise impractical uphill ET reactions.