Hot Exciton Dissociation in a Conjugated Polymer

Abstract

A model has been developed to treat field-assisted ultrafast on-chain dissociation of optical excitations in a conjugated polymer. Conversion of the excess photon energy above the singlet exciton into the vibrational heat bath of a polymer segment is considered as a main source of the energy required for charges to escape from a potential well formed by a superposition of the Coulomb and external electric fields. The calculated yield of carrier photogeneration increases strongly with increasing field but is independent of the temperature in good quantitative agreement with data obtained by Barth et al. [Chem. Phys. Lett. 288, 147 (1998)] on weakly disordered conjugated ladder-type poly-phenylene.