Halogen-substituted zinc(II) phthalocyanines: Spectral properties and structure of thin films

Abstract

In this work, the effect of the type of halogen substituents on the structure, morphology, and conductivity of thin films of zinc(II) phthalocyanines ZnPcHal4 (Hal = F, Cl, Br, I), deposited both by evaporations in vacuum and by a spin coating technique was studied. The influence of these different halogen substituents on the spectral properties of ZnPcHal4 derivatives was also investigated. For this purpose, the density-functional theory calculations of the vibrational spectra of ZnPcHal4 were carried out. It was shown that ZnPcHal4 (Hal = F, Cl) films obtained by physical vapor deposition (PVD) were polycrystalline and consisted of well-distinguishable rounded grains, whereas the introduction of the bulk bromine and iodine substituents led to the formation of amorphous films both in the PVD process and during spin coating deposition. The lateral d.c. conductivity of the films was shown to decrease in the order ZnPcCl4 > ZnPcF4 > ZnPcBr4 > ZnPcI4. The conductivity of PVD films, which were characterized by higher crystallinity and order, was higher than that of spun films.