The morphological dependence of charge transport in a soluble luminescent conjugated polymer

Charge transport in poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] is studied by employing the time-of-flight technique. Film morphology plays a key role in determining the charge transport properties. Samples prepared from toluene feature non-dispersive transport. However, after thermal annealing, charge transport is no longer nondispersive and hole mobility drops for about one order of magnitude. Near-field scanning optical microscope images show that annealing enhanced film inhomogeneity. We propose that the inhomogeneity is responsible for the changes in the transport properties. (C) 2002 Elsevier Science B.V. All rights reserved.