Impact of ring torsion on the intrachain mobility in conjugated polymers

We have developed a fully three-dimensional model based on the solution of the time-dependent Schr\"odinger equation for studies of polaron mobility in twisted polymer chains. Variations in ring torsion angles along a conjugated polymer chain are shown to have a strong effect on the intrachain charge carrier mobility. An increase in ring torsion between two neighboring monomers can cause electron localization and then result in a transition of the type of transport from adiabatic polaron drift to nonadiabatic polaron hopping. In particular, we show the sensitivity for such a transition in the case of random variations in the ring torsion angles along a poly(phenylene vinylene) chain. The effective energy barrier associated with the change in torsion angle also depends on the applied electric-field strength, and by increasing the field strength a transition back to adiabatic transport can be obtained.