Growth Process of Phthalocyanine Films Deposited on 3,4,9,10-Perylene Tetracarboxylic Dianhydride Template Layers

The thickness dependences of the molecular orientation and crystal structure of phthalocyanine (H2Pc) films deposited on 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA) template layers were investigated by X-ray diffraction (XRD) analysis and infrared reflection absorption spectroscopy (IR-RAS). It was found that the H2Pc molecular plane is almost parallel to the substrate surface when the H2Pc layer thickness is less than 10 nm, however, it tilts with increasing H2Pc thickness. In a H2Pc thickness of more than 300 nm, the tilt angle of the H2Pc molecular plane approached 26.5°, suggesting the growth of α-H2Pc with the b-axis perpendicular to the substrate surface. The images obtained by scanning electron microscopy showed that the thin and thick H2Pc layers have a columnar structure and a tangled fiber structure, respectively, consistent with the results of XRD analysis and IR-RAS.