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The molecular orientation and optical properties of phthalocyanine (H2Pc) films grown on glass with a 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) intermediate layer were investigated by infrared reflection absorption spectroscopy and absorption spectrum analysis. The orientation of the H2Pc molecular plane became almost parallel to the substrate surface with the introduction of a thin PTCDA layer on a glass substrate during initial growth. However, the orientation of the H2Pc molecular plane turned from parallel to oblique with increasing layer thickness, and finally the angle approached 26.5°, which indicates the formation of a crystalline phase of α-H2Pc with the b-axis perpendicular to the substrate surface. The optical absorption of the film was significantly affected by the molecular arrangement, and the importance of molecular orientation control was suggested.

The influences of a 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) layer on the molecular orientation and crystalline structure of phthalocyanine (H2Pc) films grown on PTCDA/glass structures were studied by X-ray diffraction analysis, grazing incidence X-ray diffraction analysis, atomic force microscopy and infrared reflection absorption spectroscopy. The orientation of the H2Pc molecular plane became parallel to the substrate surface with the introduction of a thin PTCDA layer on a glass substrate, although the molecular plane of a H2Pc film without a PTCDA layer was almost perpendicular to the substrate surface. Such a parallel orientation of the H2Pc molecular plane was observed even when the PTCDA layer thickness was only 5 Å. It was found that the intensity of the optical absorption of a H2Pc film is significantly influenced by the molecular orientation of H2Pc, and the importance of controlling this molecular orientation is suggested.