Dopant-assisted charge carrier photogeneration in conjugated polymers

A model of two-step carrier photogeneration in doped conjugated polymers is suggested. On the first step, a dissociation of a relaxed exciton into a Coulombically bound geminate pair (GP) occurs at a charge transfer center which consists of a polymer chain and a nearby dopant or deep trap. On the second step, the GP dissociates into free carriers due to carrier release from the on-chain potential well formed by the Coulomb and external fields. The generation yield is shown to be practically field- and temperature-independent in a polymer with a small on-chain effective carrier mass.