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Dynamical coupling and negative differential resistance from interactions across the molecule-electrode interface in
1Department of Chemistry and the Ilze-Katz Institute for Nano-Scale Science and Technology, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
The Journal of Chemical Physics
|October 29, 2013
Summary
A novel mechanism explains negative differential resistance (NDR) in molecular junctions, driven by Coulomb interactions. This interaction enhances coupling, causing non-monotonic voltage dependence and NDR, aligning with experimental findings.
Area of Science:
- Condensed Matter Physics
- Molecular Electronics
- Quantum Transport
Background:
- Negative differential resistance (NDR) is an unusual electronic phenomenon observed in molecular junctions.
- Existing models do not fully explain the origins of NDR in these systems.
- Strong electron-electron interactions are suspected to play a role.
Purpose of the Study:
- To propose and investigate a novel mechanism for NDR in molecular junctions.
- To elucidate the role of interface Coulomb interactions in electronic transport.
- To explore the impact of these interactions on thermoelectric properties.
Main Methods:
- Utilized a self-consistent non-equilibrium Green's function (NEGF) approach.
- Modeled strong Coulomb interactions between molecular electrons and electrode-proximal atoms.
- Analyzed the voltage-dependent behavior of molecule-electrode coupling.
Main Results:
- Demonstrated that interface Coulomb interaction induces electron-hole binding, enhancing coupling.
- Showed that this effective coupling is non-monotonic with bias voltage, leading to NDR.
- Confirmed model agreement with experimental observations correlating NDR and coupling strength.
Conclusions:
- Interface Coulomb interactions provide a viable mechanism for NDR in molecular junctions.
- The proposed model offers insights into the origin of NDR and its link to coupling.
- Interface Coulomb effects significantly influence both I-V characteristics and thermoelectric properties.
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