Evidence of the Key Role of Metal-Molecule Bonding in Metal-Molecule-Metal Transport Experiments

Abstract : The transport properties of two oligothiophene derivatives, that differ only by the chemical group coupling to gold, are compared. It is shown that the role of the coupling group in the transport properties can be decoupled from that of the conjugated body of the molecules and that Se provides a better electronic coupling than S. These results are accounted for semi-quantitatively within the frame of the scattering theory of transport, using results from UPS experiments as inputs for the position in energy of the molecular orbitals with respect to the electrodes Fermi level