The scanning probe microscopy of the structural, elastic and conductive properties of two-component phthalocyanines

Thin films of two-component H₂Pc, PdPc, PbPc, CuPc phthalocyanines were studied by scanning probe microscopy methods. Young's modulus values of the phthalocyanines films were measured, which made it possible to optimize the regimes for studying soft phthalocyanine films and to select suitable probes with proper stiffness and the magnitude of the force acting onto the surface. For all films, the electric field induced reversible local conductivity switching effect was studied. It is shown that under room conditions it is possible to reversibly change the value of the local conductivity of a copper phthalocyanine film approximately by an order of magnitude. When conducting the experiment under vacuum conditions, a significant weakening of this effect occurs. It has been established that for a CuPc film, a pressure of 20 mbar is the lower boundary value for creating regions of increased conductivity. The observed effect is explained by the penetration of OH⁻ ions (from the surface adsorbed water film) into the phthalocyanine film with the subsequent formation of oxygen-containing complexes that increase conductivity. (paper)