title: Fabrication of steady junctions consisting of alpha,omega-bis(thioacetate) oligo(p-phenylene vinylene)s in nanogap electrodes.
abstract: For obtaining molecular devices using metal-molecule-metal junctions, it is necessary to fabricate a steady conductive bridge-structure; that is stable chemical bonds need to be established from a single conductive molecule to two facing electrodes. In the present paper, we show that the steadiness of a conductive bridge-structure depends on the molecular structure of the bridge molecule for nanogap junctions using three types of modified oligo(phenylene vinylene)s (OPVs): alpha,omega-bis(thioacetate) oligo(phenylene vinylene) (OPV1), alpha,omega-bis(methylthioacetate) oligo(phenylene vinylene) (OPV2), and OPV2 consisting of ethoxy side chains (OPV3). We examined the change in resistance between the molecule-bridged junction and a bare junction in each of the experimental Au-OPV-Au junctions to confirm whether molecules formed steady bridges. Herein, the outcomes of whether molecules formed steady bridges were defined in terms of three types of result; successful, possible and failure. We define the ratio of the number of successful junctions to the total number of experimental junctions as successful rate. A 60% successful rate for OPV3 was higher than for the other two molecules whose successful rates were estimated to be approximately 10%. We propose that conjugated molecules consisting of methylthioacetate termini and short alkoxy side chains are well suited for fabricating a steady conductive bridge-structure between two facing electrodes.
authors.affiliation: Nanotechnology Research Institute, Tsukuba, Ibaraki 305-8562, Japan.
authors.forename: Tien-Tzu
authors.initials: TT
authors.lastname: Liang
authors.forename: Yasuhisa
authors.initials: Y
authors.lastname: Naitoh
authors.forename: Masayo
authors.initials: M
authors.lastname: Horikawa
authors.forename: Takao
authors.initials: T
authors.lastname: Ishida
authors.forename: Wataru
authors.initials: W
authors.lastname: Mizutani