Tuning surface d bands with bimetallic electrodes to facilitate electron transport across molecular junctions
Journal
Nature Materials
Journal Volume
20
Journal Issue
5
Pages
658-664
Date Issued
2021
Author(s)
Abstract
Understanding chemical bonding and conductivity at the electrode–molecule interface is key for the operation of single-molecule junctions. Here we apply the d-band theory that describes interfacial interactions between adsorbates and transition metal surfaces to study electron transport across these devices. We realized bimetallic Au electrodes modified with a monoatomic Ag adlayer to connect α,ω-alkanoic acids (HO2C(CH2)nCO2H). The force required to break the molecule–electrode binding and the contact conductance Gn=0 are 1.1 nN and 0.29 G0 (the conductance quantum, 1 G0 = 2e2/h ? 77.5 μS), which makes these junctions, respectively, 1.3–1.8 times stronger and 40–60-fold more conductive than junctions with bare Au or Ag electrodes. A similar performance was found for Au electrodes modified by Cu monolayers. By integrating the Newns–Anderson model with the Hammer–N?rskov d-band model, we explain how the surface d bands strengthen the adsorption and promote interfacial electron transport, which provides an alternative avenue for the optimization of molecular electronic devices. ? 2021, The Author(s), under exclusive licence to Springer Nature Limited.
Subjects
Chemical bonds; Electrodes; Molecules; Transition metals; Conductance quantum; Contact conductance; Electron transport; Interfacial interaction; Molecular electronic device; Molecular junction; Single-molecule junctions; Transition metal surfaces; Electron transport properties
Type
journal article