Thermal Effects on Charge Transport in Conjugated Polymers

Abstract

Field dependent polaron transport in a conjugated polymer chain is studied numerically with local thermal fluctuations taken into account. Within a dynamical evolution method, a polaron moves from the left to the right side of the polymer chain in the presence of an applied electric field. Local lattice fluctuations are assumed to occur in a random way. The local thermal fluctuations are found to be equivalent to a potential barrier for the polaron. The range of the thermally disturbed region in the molecule and the effective temperature difference resulted from asymmetric thermal absorptions determine the height of the barrier. The intra-molecule polaron mobility obeys a logarithmic law in low electric field range provided that there exist asymmetric thermal absorptions within the molecule.