Oxygen influence on the conductivity of copper phthalocyanine vacuum-deposited thin films

Temperature dependencies of the conductivity in thin vacuum-evaporated alpha-form copper phthalocyanine (CuPc) films with columnar structure were investigated. It was found that the CUPC-O-2 interaction is fully reversible. Oxygen can be removed after heating the film at 400 K in Ar atmosphere. The CUPC-O-2 interaction could be interpreted as a two-stage process of formation and subsequent decay of charge-transfer complexes, finally producing free charge carriers. The lower value of the activation energy measured cannot be connected with a hysteresis in the CUPC-O-2 interaction. (C) 2004 Elsevier Ltd. All rights reserved.