Surface potential of phthalocyanine Langmuir-Blodgett films on metal electrodes

Surface potential of Cu-tetra-tert-butyl-phthalocyanine (CuttbPc) Langmuir-Blodgett (LB) films on metal electrodes were measured in a dark vacuum vessel at various temperatures as a function of the number of deposited layers. It was found that the potential built across CuttbPc LB film is a result of the displacement of electronic charges between metal electrodes and film. The spatial charge distribution in CuttbPc LB films was determined on the order of nanometer scale, and the distribution of the electronic density of states was also determined. Finally, we concluded that electrostatic phenomena occurring at the CuttbPc/metal interface is explained by assuming the presence of both electron donating and accepting states in CuttbPc LB films at the film/metal interface.