PHOTOCONDUCTION IN POLY(3-ALKYLTHIOPHENE) .2. CHARGE TRANSPORT

Hole motion in poly(dodecylthiophene) has been investigated by means of time of flight (TOF) studies and space charge limited conduction involving hole injection from a gold anode. The decrease of the hole mobility with temperature above 290 K parallels the increase of disorder manifest in the absorption spectra. At lower temperatures TOF signals become dispersive. The results are interpreted in terms of hopping motion within an energetically random array of hopping sites formed by ordered chain segments. The polaron contribution towards the activation energy for charge carrier motion is found negligible relative to the disorder contribution.