The effect of cyclic voltammetry on the crystalline order of PdPc thin films

The degree of crystalline order of evaporated and cast palladium phthalocyanine films was investigated before and after they were submitted to a voltammetric process. X-ray diffraction and UV-vis spectroscopy measurements demonstrated that the electrochemical treatment improves the crystalline quality of the films. The X-ray results revealed an increase of the average size of the crystallites composing the films as well as a decrease in the spacing between the lattice planes in the direction perpendicular to the surface of the film. Optical measurements showed that the electrochemical treatment also introduces an appreciable degree of in-plane ordering. These improvements of crystalline order are observed in both types of films, cast and evaporated, which indicates that the ordering is a direct consequence of the electrochemical treatment and not of the method used for the film deposition.

Electrochemically induced orientation of copper phthalocyanine thin films

The dependence of the electrochromic and organizational behaviors of copper phthalocyanine ( CuPc ) evaporated thin films on oxidation level have been investigated. UV-vis experiments with CuPc thin film obtained before cyclic voltammetry display two Q bands in the region between 600 and 700 nm, which correspond to the α form of CuPc . The FTIR spectra show an improved molecular orientation of CuPc molecules, obtained after the electrochemical process. Molecules in the film in the oxidized state (1.27 V) display a plane parallel to the film surface, indicating a flat-on molecular orientation. Spectrum changes observed after one complete voltammetric cycle (between −0.5 and 1.5 V) show an evolution from a mixed molecular organization to an edge-on organization.