Transition from Tunneling to Hopping in Single Molecular Junctions by Measuring Length and Temperature Dependence
- 29 July 2010
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 132 (33), 11658-11664
- https://doi.org/10.1021/ja1040946
Abstract
The charge transport characteristics of a family of long conjugated molecular wires have been studied using the scanning tunneling microscope break junction technique. The family consists of four wires ranging from 3.1 to 9.4 nm in length. The two shortest wires show highly length dependent and temperature invariant conductance behavior, whereas the longer two wires show weakly length dependent and temperature variant behavior. This trend is consistent with a model whereby conduction occurs by two different mechanisms in the family of wires: by a coherent tunneling mechanism in the shorter two and by an incoherent charge hopping process in the longer wires. The temperature dependence of the two conduction mechanisms gives rise to a phenomenon whereby at elevated temperatures longer molecules that conduct via charge hopping can yield a higher conductance than shorter wires that conduct via tunneling. The evolution of molecular junctions as the tip retracts has been studied and explained in context of the characteristics of individual transient current decay curves.Keywords
This publication has 36 references indexed in Scilit:
- Challenges in Distinguishing Superexchange and Hopping Mechanisms of Intramolecular Charge Transfer through Fluorene OligomersThe Journal of Physical Chemistry A, 2008
- Single Molecule Junctions Formed via Au−Thiol Contact: Stability and Breakdown MechanismJournal of the American Chemical Society, 2007
- Electron transport in molecular junctionsNature Nanotechnology, 2006
- Measurement of single molecule conductivity using the spontaneous formation of molecular wiresPhysical Chemistry Chemical Physics, 2004
- Measurements of Single-Molecule Electromechanical PropertiesJournal of the American Chemical Society, 2003
- Comparison of Electronic Transport Measurements on Organic MoleculesAdvanced Materials, 2003
- ELECTRONTRANSMISSIONTHROUGHMOLECULES ANDMOLECULARINTERFACESAnnual Review of Physical Chemistry, 2001
- Conformational Gating of Long Distance Electron Transfer through Wire-like Bridges in Donor−Bridge−Acceptor MoleculesJournal of the American Chemical Society, 2001
- Solvent Reorganization in Long-Range Electron Transfer: Density Matrix ApproachThe Journal of Physical Chemistry A, 1998
- Electron Transfer Rates in Bridged Molecular Systems: A Phenomenological Approach to RelaxationThe Journal of Physical Chemistry A, 1997