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Molecular transport junctions: current from electronic excitations in the leads
Michael Galperin1, Abraham Nitzan, Mark A Ratner
1Department of Chemistry and Nanotechnology Center, Northwestern University, Evanston, Illinois 60208, USA.
Physical Review Letters
|May 23, 2006
Summary
Electron-hole excitations in molecular junctions significantly impact source-drain current. This effect can dominate conduction, especially in molecules with strong charge transfer transitions.
Area of Science:
- Condensed Matter Physics
- Molecular Electronics
- Quantum Chemistry
Background:
- Molecular junctions are crucial for nanoscale electronic devices.
- Understanding charge transport mechanisms is key to device performance.
Purpose of the Study:
- To investigate the influence of electron-hole excitations on current in molecular junctions.
- To determine conditions under which these excitations dominate conduction.
Main Methods:
- A theoretical model of a two-level bridge connecting free electron reservoirs was employed.
- Analysis focused on the interplay between elastic current and electron-hole excitations.
Main Results:
- Coupling of the molecular bridge to electron-hole excitations markedly affects source-drain current.
- For molecules with strong charge transfer transitions, this contribution can surpass Landauer elastic current.
- Electron-hole excitations can become the dominant conduction pathway.
Conclusions:
- Electron-hole excitations play a significant role in molecular junction conduction.
- The findings are particularly relevant for molecules exhibiting strong charge transfer.
- This highlights a non-trivial transport mechanism beyond simple elastic tunneling.
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