Coherent dynamics of singlet fission controlled by nonlocal electron-phonon coupling

TL;DR

This study models singlet fission in tetracene using a Frenkel-CT mixing framework, revealing how nonlocal electron-phonon interactions influence quantum coherence, triplet yield, and fission rates, aligning with experimental data.

Contribution

It introduces a comprehensive simulation incorporating local and nonlocal phonon baths to elucidate the role of nonlocal electron-phonon coupling in singlet fission dynamics.

Findings

Quantum coherence enhances singlet fission efficiency.

Nonlinear triplet yield dependence on singlet density.

Calculated fission rate matches experimental results.

Abstract

Based on the Frenkel-charge transfer (CT) mixing model of singlet fission (SF), we incorporate both the local and nonlocal phonon baths in the Hamiltonian and adopt the algorithm of time-dependent density matrix renormalization group to simulate the fission process in tetracene. The endergonic SF is found to be facilitated by the robust quantum coherence, which concurrently gives rise to a notable quantum beating effect. Controlled by the nonlocal electron-phonon coupling, the density of triplet yield manifests a nonlinear relationship with the singlet density. As a result, the fission rate in tetracene is explicitly obtained, which is in agreement with the experimental measurement.