Carlotti Marco, Degen Maarten, Zhang Yanxi, Chiechi Ryan C
Stratingh Institute for Chemistry & Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 4, 9747 AG Groningen, The Netherlands.
J Phys Chem C Nanomater Interfaces. 2016 Sep 15;120(36):20437-20445. doi: 10.1021/acs.jpcc.6b07089. Epub 2016 Aug 23.
Large-area tunneling junctions using eutectic Ga-In (EGaIn) as a top contact have proven to be a robust, reproducible, and technologically relevant platform for molecular electronics. Thus far, the majority of studies have focused on saturated molecules with backbones consisting mainly of alkanes in which the frontier orbitals are either highly localized or energetically inaccessible. We show that self-assembled monolayers of wire-like oligophenyleneethynylenes (OPEs), which are fully conjugated, only exhibit length-dependent tunneling behavior in a low-O environment. We attribute this unexpected behavior to the sensitivity of injection current on environment. We conclude that, contrary to previous reports, the self-limiting layer of GaO strongly influences transport properties and that the effect is related to the wetting behavior of the electrode. This result sheds light on the nature of the electrode-molecule interface and suggests that adhesive forces play a significant role in tunneling charge-transport in large-area molecular junctions.
使用共晶镓铟（EGaIn）作为顶部接触的大面积隧道结已被证明是分子电子学中一个强大、可重复且与技术相关的平台。到目前为止，大多数研究都集中在主要由烷烃组成主链的饱和分子上，其中前沿轨道要么高度局域化，要么在能量上难以接近。我们表明，完全共轭的线状寡聚亚苯基乙炔（OPEs）自组装单分子层在低氧环境中仅表现出长度依赖性隧道行为。我们将这种意外行为归因于注入电流对环境的敏感性。我们得出结论，与之前的报道相反，GaO的自限层强烈影响传输特性，且该效应与电极的润湿性有关。这一结果揭示了电极 - 分子界面的本质，并表明粘附力在大面积分子结的隧道电荷传输中起重要作用。
