Polaron stability under collision with different defects in conjugated polymers

Polarons are charge carriers generated by doping or photo-excitation in conjugated polymers. The dynamics of polaron-soliton and polaron-bipolaron collisions in conjugated polymers is numerically studied using the Su-Schrieffer-Heeger model extended to include an external electric field, Coulomb interactions, and impurities interactions. The time-dependent unrestricted Hartree-Fock approximation is considered. The stability of polarons determines whether the charge transport by these structural defects are modified under these collisions. An energetic analysis determines whether the energy levels associated with solitons, polarons, and bipolarons change with collisions. We show that these structural defects have great stability in collisions. The bipolaron mobility does not change under polaron-bipolaron collisions. In contrast, we find that there is a great exchange of linear momentum in the collisions between solitons and polarons. (C) 2006 Wiley Periodicals, Inc.