Initial molecular orientation of phthalocyanines on oxide substrates

The molecular orientation of ultra‐thin films of copper phthalocyanine and perfluoro‐copper phthalocyanine (F16PcCu) on various oxide substrates is examined with polarisation dependent NEXAFS spectroscopy. The focus is on the adsorption geometry of the first adsorbed layers, which can strongly vary from the observed orientation in thin‐films above the few nanometre regime. Native silicon dioxide, indium tin oxide and titanium dioxide are chosen for their relevance to technical applications. On chemically and thermally cleaned oxide surfaces a predominantly standing initial orientation is preferred, while on ion bombarded activated surfaces the molecules prefer a lying orientation.