Molecular Electron Transfer in Optical Cavities: From Excitonic to Vibronic Polaritons

TL;DR

This paper investigates how strong light-matter coupling in optical cavities influences molecular electron transfer, revealing saturation effects, vibronic interactions, and quantum interference phenomena through advanced numerical simulations.

Contribution

It introduces a comprehensive model incorporating nuclear-coordinate dependence and vibronic effects, providing new insights into cavity-modified electron transfer mechanisms.

Findings

ET rate saturates in strong coupling regime

Vibronic polariton formation causes oscillatory ET rate dependencies

Quantum interference among transfer pathways influences ET dynamics

Abstract

Strong coupling between molecular excitations and quantized electromagnetic fields in optical cavities provides a powerful means to control the physical and chemical properties of molecular systems. Here, we study electron transfer (ET) dynamics in cavity-coupled molecules using the numerically exact hierarchical equations of motion (HEOM) method, which captures nonperturbative and non-Markovian effects beyond standard perturbative theories. We identify distinct resonance and collective effects associated with polariton formation and show that the ET rate saturates in the strong-coupling regime, a feature not captured by perturbative approaches. We further extend the cavity-modified ET model by incorporating the nuclear-coordinate dependence of molecular electric dipole moments, which gives rise to a three-body interaction involving molecular electronic and vibrational degrees of freedom and cavity photons. This vibronic polariton formation leads to non-monotonic, oscillatory dependencies of the ET rate on the light-matter coupling strength and cavity frequency, which we attribute to quantum interference among multiple transfer pathways. These findings establish cavity-modified electron transfer as a multichannel quantum process governed by the interplay of electronic, vibrational, and photonic degrees of freedom.