Symmetry-Breaking Manipulated Channel Ergodicity in Intramolecular Singlet Fission Uncovered Statistically by Molecular Dynamics Samplings

Persistent structure dynamics ofchromophores in a solvent hasa pivotal influence on singlet fission (SF) phenomena through breakingstructure symmetry and tuning electronic properties. However, clarifyinghow the dynamic factors manipulate the SF dynamics faces major challenges.Here, we for the first time propose a dynamic symmetry-breaking strategyfor manipulating intramolecular SF and unveil channel-ergodic charactersby constructing transient configuration space of an individual solvatedmonomer in a chromophore-in-solvent ensemble by sampling its dynamicstrajectory. Dynamic symmetry-breaking leads an SF ensemble to findpossible SF channels (i.e., subensembles), characterized by a broadenergy population of a charge-transfer state and its coupling witha locally excited state, and the populated multichannels featuringdistinct probability distributions determine the dominant SF mechanismand also reveal channel conversion and ergodic behavior, agreeinghighly with experimental observations. This work emphasizes the vitalrole of the inherent structure dynamics of a chromophore in solventin manipulating such photophysics characteristics by evaluating theirsymmetry-breaking properties statistically.

Automated summary

The persistent structure dynamics of chromophores in a solvent play a crucial role in singlet fission (SF) phenomena by breaking structure symmetry and tuning electronic properties. However, understanding how dynamic factors manipulate SF dynamics is challenging. In this study, a dynamic symmetry-breaking strategy is proposed to manipulate intramolecular SF and reveal channel-ergodic characters. The results show that dynamic symmetry-breaking leads to the formation of SF channels with distinct probability distributions, determining the dominant SF mechanism and exhibiting channel conversion and ergodic behavior, consistent with experimental observations.