# Fluctuating exchange interactions enable quintet multiexciton formation in singlet fission

## TL;DR

This paper presents a theoretical model explaining the formation of a quintet multiexciton state during singlet fission, driven by fluctuating exchange interactions, supported by ESR spectrum simulations.

## Contribution

It introduces a novel theoretical framework linking time-varying exchange coupling to multiexciton formation in singlet fission.

## Key findings

- Simulated ESR spectra match experimental observations.
- Identified conditions for adiabatic and diabatic spin state transitions.
- Provided insights into the role of fluctuating exchange interactions.

## Abstract

Several recent electron spin resonance studies have observed a quintet multiexciton state during the singlet fission process. Here we provide a general theoretical explanation for the generation of this state by invoking a time-varying exchange coupling between pairs of triplet excitons, and subsequently solving the relevant time-varying spin Hamiltonian for a range of transition times. We simulate experimental ESR spectra and draw qualitative conclusions about the adiabatic/diabatic transition between triplet pair spin states.

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Source: https://tomesphere.com/paper/1906.08921