Electronic structure at the interface between metals and new materials for organic light emitting diodes

Electronic structure at the interface between gold and aromatic 1,3,4-oxadiazoles was studied by means of ultraviolet photoelectron spectroscopy (UPS). Thin films of 1,3,4-oxadiazoles were prepared in situ by evaporation from pinhole sources on freshly prepared gold on a Si substrate. We determine the frontier orbitals positions at the interface oxadiazoles/Au finding evidence for the presence of a dipole layer. Furthermore, the complete valence electronic band structure has been determined from the UPS spectra. The spectral features corresponding to the top of the valence band and dominating the electronic properties of this material were assigned to the different molecular eigenstates by comparison with simulated spectra from quantum chemical calculations.