THE EFFECT OF OXYGEN ON THE ELECTRICAL CHARACTERISTICS OF TRICLINIC LEAD PHTHALOCYANINE

The electrical characteristics of triclinic PbPc have been studied for thin films exposed to oxygen and dry air at atmospheric pressure for periods up to 25 weeks. Conductivity is found to be critically dependent upon the presence of O2, prolonged exposure enhancing conductivity and decreasing the conduction activation energies. Both ohmic and space-charge-limited conduction (SCLC) are observed, together with a low temperature mechanism which may be variable range hopping. Oxygen exposure leads to more rapid oxygen doping of the films than exposure to dry air. SCLC is controlled by either an exponential trap distribution or a simple dominant level dependent upon the film exposure/annealing history. Oxygen impurities appear to play a dual role of both acceptors and trap levels.