Photo-generation of polaron pairs in coupled chains of polyacetylene

The dynamics of photo-excitations to describe the generation mechanism of charged polaron pairs belonging to parallel conjugated polymer chains is investigated. The interchain interaction of two parallel chains is studied numerically through the dynamics of the electron-lattice system in the presence of an electric field by using the an extension of the Su-Schrieffer-Heeger model. The electric field is introduced in terms of a time-dependent vector potential which is present in the Hamiltonian through a Peierls substitution of the phase factor to the transfer integral. The lattice dynamical relaxation from the photo-excited states in a few tenths of femtosecond to charged polarons belonging to neighboring chains is determined by the numerical resolution of the electronic and lattice equations of motion. It is shown in the present study that interchain interactions are determinant in the photo-carrier quantum efficiency calculation in conjugated polymers. (C) 2007 Elsevier B.V. All rights reserved.