Laterally Resolved Orientation and Film Thickness of Polar Metal Chlorine Phthalocyanines on Au and ITO

The molecular orientation and homogeneity of gallium(III) and aluminum(III) chlorine phthalocyanine (GaClPc and AlClPc) are studied on flat (gold single crystal, Au(100)) and rough surfaces (indium tin oxide, ITO) by Raman spectroscopy in combination with X-ray absorption spectroscopy (XAS) in detail. In the case of Raman spectroscopy, Euler angles are used to describe the geometry while Raman imaging provides insight into homogeneity. For XAS, synchrotron radiation is applied to study the angle dependence of the excitation structure. On Au(100) the molecules are highly ordered and tend to align parallel to the surface (lying) with a layer by layer growth mode. Contrarily, on technically relevant substrates, as in the case of ITO, less ordered films due to the roughness of the surface nature are present. The results are discussed in relation to the substrate's nature and the influence of dipole moments.