Escape rate of a charge carrier from a semiconducting polymer chain

Abstract

Charge carriers in amorphous semiconducting polymers diffuse rapidly along the polymer chains, hopping less frequently to neighboring chains. The escape time required on average to hop to a neighboring chain affects the design of new polymers and determines the relative importance of other system parameters such as polymer rigidity or polymer molecular weight. We provide a general expression for the escape rate, which lends itself to a more simplified and transparent expression in the limit of vanishing reorganization energy. The escape rate appears to be more sensitive to disorder and temperature than the intra-chain transport. We show how the parameters required for the evaluation of this rate can be derived from a combination of classical and quantum chemical models already used to characterize semiconducting polymers, and we provide an illustration based on two realistic polymeric materials.