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Updated: Dec 12, 2025

All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics
Published on: January 19, 2018
Long-Range Charge Transport in Diazonium-Based Single-Molecule Junctions
Xinlei Yao1, Xiaonan Sun1, Frédéric Lafolet1
1Université de Paris, ITODYS, CNRS-UMR 7086, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France.
Abstract:
Thin layers of cobalt and ruthenium polypyridyl-oligomers with thicknesses between 2 and 8 nm were deposited on gold by electrochemical reduction of diazonium salts. A scanning tunneling microscope was used to create single-molecule junctions (SMJs). The charge transport properties of the Au-[Co(tpy)2]-Au (n = 1-4) SMJs do not depend markedly on the oligomer length, have an extremely low attenuation factor (β ∼ 0.19 nm-1), and do not show a thickness-dependent transition between two mechanisms. Resonant charge transport is proposed as the main transport mechanism. The SMJ conductance decreases by 1 order of magnitude upon changing the metal from Co to Ru. In Au-[Ru(tpy)2]-Au and Au-[Ru(bpy)3]-Au SMJs, a charge transport transition from direct tunneling to hopping is evidenced by a break in the length-dependent β-plot. The three different mechanisms observed are a clear molecular signature on transport in SMJs. Most importantly, these results are in good agreement with those obtained on large-area molecular junctions.
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