Ultraviolet photoelectron spectroscopy of thin films of new materials for multilayer organic light emitting diodes

The electronic structure of thin films of new heterocyclic compounds was studied by means of ultraviolet photoelectron spectroscopy (UPS) and near edge X-ray absorption fine structure (NEXAFS). The complete one-dimensional valence electronic band structure has been determined from the UPS spectra. The spectral features that correspond to the top of the valence band and that dominate the electronic properties of this material were assigned to the different molecular eigenstates by comparison with simulated spectra from quantum chemical calculations. NEXAFS measurements were carried out on the same films.