Study of electrical and dielectric properties of palladium-phthalocyanine (PdPc) in pellet form

A pressed pellet of palladium phthalocyanine (PdPc) was characterized by impedance spectroscopy. The dielectric properties were investigated in a wide frequency (10(2)-10(8) Hz) and temperature (300-440 K) ranges. The values of activation energy, the relaxation time, and the critical frequency were closed to each other, indicating that the same type of charge carriers is responsible for electrical conduction and relaxation phenomenon in the samples. According to the values of the frequency exponent s and the conductivity, the conduction mechanism was determined for both the as prepared and annealed films. The AC conductance obeyed Jonscher's universal power law, and the conduction mechanism was interpreted by the overlapping large polaron tunneling (OLPT) process. Thus, a significant correlation was established between the temperature and activation energy. A metal semiconductor transition of this material was observed at 440 K. The obtained results demonstrate the potential of this material for photovoltaic applications.