Polaron formation dynamics in conducting polymers

In the framework of the extended Su-Schrieffer-Heeger model, the formation mechanism of a polaron is studied by calculating the interaction force between a hot electron and the lattice in a conducting polymer. It is found that the formation of a polaron depends upon the energy of the hot electron. Regardless of whether an electron comes from an injection, doping or a dissociated state of a polaron, it will be trapped by the lattice to form a polaron only when its energy is lower than a critical value. The force field between the lattice and the hot electron with a lower energy has a localized characteristic, which causes polaron formation in a conducting polymer. For a hot electron with much higher energy, the force field is extended over the whole polymer chain, which cannot trap the electron and therefore a polaron does not form in this case.