Effect of Molecular Chain Orientation on Carrier Transport and Trapping in Polymer Blends

Carrier transport and trapping effects, as they are influenced by molecular chain orientation, were investigated by Thermally Stimulated Currents (TSC) and Current-Voltage (IV) characteristics in the samples of poly(9-vinylcarbazole) (PVK) doped with 30% wt 4-dibutylamino-4′-nitrostilbene (DBANS). The orientation of DBANS, diode-like molecules, was performed by electric field above the glass transition temperature. We demonstrate that the orientation of polar molecules causes significant changes both in IV dependencies and the TSC spectra. Changes of the TSCs induced by orientation were expressed best in the temperature range of 280–290 K. They could be attributed to the thermally activated process with activation energy of about 0.38 eV.