Computational characterization of charge transport resiliency in molecular solids

Organic semiconductors have found utility in a diverse array of applications. A key property impacting device performance is the charge transport mobility of the molecular solids making up the active layer in these devices. There is increasing interest in accessing, quantifying, and understanding the resilience of charge transport mobility to thermal, mechanical, and chemical perturbations in molecular solids. Here, we integrate molecular simulations with graph characterization to quantify the resilience of charge transport. We consider all-atom simulations of the PTB7 system and build on earlier graph approaches to rapidly characterize the charge mobility of the PTB7 molecular simulations. We introduce graph centrality measures to rank order monomers in the molecular solid in terms of their importance to charge transport. We then systematically quantify the impact of ‘deactivating’ an increasing number of monomers on the overall charge transport mobility. This provides a measure of the resiliency of the molecular solid to increasing amounts of structural perturbations. We find that charge transport in the PTB7 system considered here is surprisingly resilient to significant amounts of monomers removed from participation in charge transport. This method provides a quantitative approach to reason about charge transport resilience and can be used to design resilient molecular solids.