Projects per year
Abstract
Developing a clearer understanding of electron tunneling through molecules is a central challenge in molecular electronics. Here we demonstrate the use of mechanical stretching to distinguish orbital pathways that facilitate tunneling in molecular junctions. Our experiments employ junctions based on self-assembled monolayers (SAMs) of homologous alkanethiols (CnT) and oligophenylene thiols (OPTn), which serve as prototypical examples of σ-bonded and π-bonded backbones, respectively. Surprisingly, molecular conductances (G molecule ) for stretched CnT SAMs have exactly the same length dependence as unstretched CnT SAMs in which molecular length is tuned by the number of CH 2 repeat units, n. In contrast, OPTn SAMs exhibit a 10-fold-greater decrease in G molecule with molecular length for stretched versus unstretched cases. Experiment and theory show that these divergent results are explained by the dependence of the molecule-electrode electronic coupling δ on strain and the spatial extent of the principal orbital facilitating tunneling. In particular, differences in the strain sensitivity of δ versus the repeat-length (n) sensitivity can be used to distinguish tunneling via delocalized orbitals versus localized orbitals. Angstrom-level tuning of interelectrode separation thus provides a strategy for examining the relationship between orbital localization or delocalization and electronic coupling in molecular junctions and therefore for distinguishing tunneling pathways.
Original language | English (US) |
---|---|
Pages (from-to) | 497-504 |
Number of pages | 8 |
Journal | Journal of the American Chemical Society |
Volume | 141 |
Issue number | 1 |
DOIs | |
State | Published - Jan 9 2019 |
Bibliographical note
Publisher Copyright:© 2018 American Chemical Society.
How much support was provided by MRSEC?
- Shared
Reporting period for MRSEC
- Period 5
PubMed: MeSH publication types
- Journal Article
Fingerprint
Dive into the research topics of 'Mechanical Deformation Distinguishes Tunneling Pathways in Molecular Junctions'. Together they form a unique fingerprint.-
MRSEC IRG-1: Electrostatic Control of Materials
Leighton, C., Birol, T., Fernandes, R. M., Frisbie, D., Goldman, A. M., Greven, M., Jalan, B., Koester, S. J., He, T., Jeong, J. S., Koirala, S., Paul, A., Thoutam, L. R. & Yu, G.
9/1/98 → …
Project: Research project
-
MRSEC Program
THE NATIONAL SCIENCE FOUNDATION, UNIVERSITY OF TEXAS RIO GRANDE VALLEY
8/1/98 → 10/31/20
Project: Research project