THE CHEMICAL AND ELECTRONIC-STRUCTURE OF THE INTERFACE BETWEEN ALUMINUM AND CONJUGATED POLYMERS OR MOLECULES

The interaction between aluminum and alpha-omega-diphenyltetradecaheptaene (DP7), alpha-sexithienyl (6T), and poly(p-phenylenevinylene) (PPV), respectively have been studied using both X-ray Photoelectron Spectroscopy (XPS) and Ultraviolet Photoelectron Spectroscopy (UPS). The UPS valence band spectra, are interpreted with the help of quantum chemical calculations based upon Modified Neglect of Diatomic Overlap (MNDO), Valence Effective Hamitonian (VEH) and ab initio Hartree-Fock methods. DP7 is a model molecule for polyacetylene, while 6T is a model molecule (an oligomer) of polythiophene. The results indicate that aluminum reacts strongly with the surfaces of all of the materials studied. The pi-electronic structure of each material was strongly modified. Furthermore, aluminum reacts preferentially with the polyene part of DP7, with the vinylene part of PPV, and with the alpha-carbons of the thiophene units of 6T.