Evaluation of charge transfer characteristics of metal-free phthalocyanine thin films by displacement current measurement

We have investigated phthalocyanine thin films using displacement current measurement. Two types of samples were prepared by vacuum evaporation method. One is the sample with a passivation film. The other is the sample without a passivation film. The passivation films were prepared by casting toluene solution containing 3 wt.% of polystyrene. The results obtained by measuring the samples elucidate the relation between carrier behavior and ambience. It is clarified that there are many traps in the sample without the passivation film. On the other hand, in the sample with the passivation film, traps are not observed. Therefore, it is concluded that the passivation film provides the constraint of oxygen doping as well as the preservation of carrier transfer system.