Nematic Order Imposes Molecular Weight Effect on Charge Transport in Conjugated Polymers

Nematic order, in the bulk or at interfaces, is ubiquitous for semiflexible conjugated polymers. Nevertheless, the effect of liquid crystalline order on charge transport remains unclear. Using an analytical model, we demonstrate that nematic order leads to an enhancement in charge mobilities when compared to isotropic chains. Furthermore, we predict a quadratic dependence of the charge mobility on molecular weight of the chains. Analysis of the probability of forming hairpin defects also shows how the persistence length affects charge transport in conjugated polymers. We speculate that the prevalence of nematic order in conjugated polymers explains the reported increase in charge mobilities with molecular weight.