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

The interaction between aluminum and alpha-omega-diphenyltetradecahept aene (DP7), alpha-sexithienyl (6T), and poly(p-phenylenevinylene) (PPV ), respectively have been studied using both X-ray Photoelectron Spect roscopy (XPS) and Ultraviolet Photoelectron Spectroscopy (UPS). The UP S valence band spectra, are interpreted with the help of quantum chemi cal calculations based upon Modified Neglect of Diatomic Overlap (MNDO ), Valence Effective Hamitonian (VEH) and ab initio Hartree-Fock metho ds. DP7 is a model molecule for polyacetylene, while 6T is a model mol ecule (an oligomer) of polythiophene. The results indicate that alumin um reacts strongly with the surfaces of all of the materials studied. The pi-electronic structure of each material was strongly modified. Fu rthermore, aluminum reacts preferentially with the polyene part of DP7 , with the vinylene part of PPV, and with the alpha-carbons of the thi ophene units of 6T.