Evidence of bipolar charge transport in PTCDA

Transient photocurrent measurements were employed to investigate the electronic charge transport in thin layers of 3,4,9,10-perylenetetracarboxylic dianhydride deposited by high-vacuum evaporation onto In-covered Si(001) substrates. Measurements performed at two different bias polarities indicate that both holes and electrons are transported in the direction perpendicular to the molecular layers. Charge transport is strongly dependent on the electric field.