Molecular Crystals and Liquid Crystals, Vol.374, 527-536, 2002
Temperature and frequency dependence of the electrical properties of thin organic films
We performed an experimental investigation of the low temperature electrical behavior of thin films of conducting polymers. Using the self-assembly technique, thin samples with a total thickness in the range of 5-60 bilayers were prepared by the alternate deposition of polypyrrole (PPY) and polythiophene acetic acid (PTAA) layers on a glass substrate. The intrinsic anisotropy of the samples was manifested in their electrical characteristics, since the temperature dependence observed for the conductivity along the surface was different from that measured in the direction perpendicular to the substrate. While the longitudinal component of the resistivity tensor changes with temperature as in a typical semiconductor, a 'metallic-like' profile is identified for the transversal component, confirming that different transport mechanisms must dominate the charge transfer along these two directions. A preliminary investigation of the dielectric characteristics of those samples has allowed us a better understanding of the charge storage processes in these samples.