The optical functions of metal phthalocyanines

The optical properties of five metal phthalocyanines (MPcs) thin films (cobalt phthalocyanine (Pc), copper Pc, iron Pc (FePc), nickel Pc, and zinc Pc), were studied by spectroscopic ellipsometry. Thin films of these MPcs were evaporated in high vacuum onto glass substrates, quartz substrates, and silicon substrates. Spectroscopic ellipsometry measurements were performed in the wavelength range 250-800 nm. The absorption spectra were measured, and the film thickness and surface roughness were studied by atomic force microscopy. Determination of optical functions was performed by simultaneous fitting of the experimental data for samples on glass and silicon substrates. Fitting results using point-to-point fitting, the Lorentz model, the modified Lorentz model, the relaxed Lorentz model, and the dual Lorentz model were compared. Models with six oscillators were used to fit the optical functions of FePc, while five oscillators were used for the other four Pcs. It was found that modifications of the Lorentz model are more suitable for description of the optical functions of the MPcs compared with the conventional Lorentz model.