title: Molecular junctions based on SAMs of cruciform oligo(phenylene ethynylene)s.
abstract: Cruciform oligo(phenylene ethynylene)s (OPEs) with an extended tetrathiafulvalene (TTF) donor moiety (OPE5-TTF and OPE3-TTF) and their simple analogues (OPE5-S and OPE3) without conjugated substituents were used to form high-quality self-assembled monolayers (SAMs) on ultraflat gold substrates. Molecular junctions based on these SAMs were investigated using conducting-probe atomic force microscopy (CP-AFM). The TTF substituent changes the molecular orbital energy levels and decreases the HOMO-LUMO energy gap, resulting in a 9-fold increase in conductance for both TTF cruciform OPEs compared to the unsubstituted analogues. The difference in electrical transport properties of the SAMs was reproduced by the theoretical transport calculations for the single molecules.
authors.affiliation: Nano-Science Center & Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark.
authors.forename: Zhongming
authors.initials: Z
authors.lastname: Wei
authors.forename: Tao
authors.initials: T
authors.lastname: Li
authors.forename: Karsten
authors.initials: K
authors.lastname: Jennum
authors.forename: Marco
authors.initials: M
authors.lastname: Santella
authors.forename: Nicolas
authors.initials: N
authors.lastname: Bovet
authors.forename: Wenping
authors.initials: W
authors.lastname: Hu
authors.forename: Mogens Brøndsted
authors.initials: MB
authors.lastname: Nielsen
authors.forename: Thomas
authors.initials: T
authors.lastname: Bjørnholm
authors.forename: Gemma C
authors.initials: GC
authors.lastname: Solomon
authors.forename: Bo W
authors.initials: BW
authors.lastname: Laursen
authors.forename: Kasper
authors.initials: K
authors.lastname: Nørgaard