FT-Raman Spectroscopy of Thin Films of Titanyl Phthalocyanine and Vanadyl Phthalocyanine

Abstract

Thin solid films of titanyl phthalocyanine (TiOPc) and vanadyl phthalocyanine (VOPc) have been vacuum evaporated onto glass substrates held at various temperatures in the range from -30 to 240°C. FT-Raman spectra have been collected using an Nd:YAG laser emitting at 1064.1 nm, a Michelson interferometer and an InGaAs detector. The characteristic vibrational wavenumbers have been assigned in the observed Raman spectra of TiOPc and VOPc molecules. Titanyl phthalocyanine and vanadyl phthalocyanine exist in a number of polymorphic forms which have characteristic x-ray diffraction patterns. Polymorphs can also be distinguished on the basis of the FT-Raman spectra. Titanyl phthalocyanine was present in an amorphous form from −30°C to room temperature. As the temperature was increased, type II TiOPc was produced. Vanadyl phthalocyanine displayed a similar behaviour. At room temperature the VOPc was amorphous, but with increasing temperature it crystallized in the type II polymorph. At 240°C the VOPc film existed in a highly preferred (010) orientation.