Electronic structure of p-sexiphenyl — metal interfaces studied by electron spectroscopies

The electronic structure of p-sexiphenyl (6P) film on metal substrates (Au and Mg) was investigated by ultraviolet photoelectron spectroscopy (UPS), metastable atom electron spectroscopy (MAES), and X-ray photoelectron spectroscopy (XPS). From MAES spectra, we found that 6P molecules form an uniform monoiayer on Au substrate, while they may form an islands on Mg substrate. UPS spectra showed that the work function of the metal substrate was changed by deposition of 6P, indicating the formation of interfacial dipole layer. No chemical reaction between the metal and the 6P molecules was observed in the XPS spectra. We also investigated the reverse system, i.e. metal on the 6P film. In contrast to the formation of the abrupt interface for the 6P/metal system, the penetration of metal atoms occurs at the metal/6P interface.