Structural and optical properties of phthalocyanine thin films grown on glass with 3,4,9,10-perylene tetracarboxylic dianhydride intermediate layer

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 H Pc 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 degrees, which indicates the formation of a crystalline phase of alpha-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.