Influence of dipolar species on charge transport in poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)‐p‐phenylene vinylene]

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Abstract
A theoretical study and experimental evidence for a decrease of the charge carrier mobility in poly[2‐methoxy‐5‐(2′‐ethylhexyloxy)‐p‐phenylene vinylene] (MEH‐PPV) under the influence of dipolar species are presented in this paper. The presence of polar species in the vicinity of an MEH‐PPV chain modifies the on‐chain site energies and consequently, due to random mutual positions and orientations, increases the width of the energy distribution of the chain transport states. The influence of energetic disorder of these states on the charge carrier mobility was modeled by means of the Monte Carlo method, based on a numerical solution of the time‐dependent Schrödinger equation in the tight‐binding approximation. It was shown that the increasing disorder destroys the resonance between charge carrier energies on adjacent sites and, therefore, limits the diffusive charge carrier motion. Copyright © 2006 John Wiley & Sons, Ltd.