Electrical properties of phenylene vinylene oligomer thin films

In this work, we report the results of electrical investigations on phenylene vinylene oligomer thin films with 5-phenyl, 4-vinyl compound (4PV). Synthesis of the oligomer powder was performed using a Wittig reaction of phosphonium salt with carbonyl group and thin films were deposited by conventional thermal evaporation under vacuum of the obtained powder. The conduction mechanisms of oligomer-based diodes were studied by measuring the current-voltage-temperature characteristics and the thermally stimulated current. In the high-temperature range, Poole-Frenkel emission is observed while, at lower temperatures, a hopping process probably occurs. Data from the thermally stimulated current measurements involve shallow traps (0.42 eV) which might originate from the 4PV/metal interface region.