Modeling the Influence of Correlated Molecular Disorder on the Dynamics of Excitons in Organic Molecular Semiconductors

In this Letter, we investigate the role of correlated molecular disorder on the dynamics of excitons in oligothiophene-based organic semiconductors. We simulate exciton dynamics using the Frenkel exciton model and we derive parameters for this model so that they reflect the specific characteristics of all-atom molecular systems. By systematically modifying the parameters of the Frenkel exciton model we isolate the influence of spatial and temporal molecular correlations on the dynamics of excitons in these systems. We find that the molecular fluctuations inherent to these systems exhibit long-lived memory effects, but that these effects do not significantly influence the dynamic properties of excitons. We also find that excitons can be sensitive to the molecular-scale spatial correlations, and that this sensitivity grows with the amount of energetic disorder within the material. We conclude that control over spatial correlations can mitigate the negative influence of disorder on exciton transport.