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Irreversibility and hysteresis in redox molecular conduction junctions
Agostino Migliore1, Abraham Nitzan
1School of Chemistry, Tel Aviv University, Tel Aviv 69978, Israel. migliore@post.tau.ac.il
Journal of the American Chemical Society
|May 18, 2013
Summary
Theoretical models explain nonlinear charge transport in redox molecular junctions, revealing how two conduction channels cause hysteresis and negative differential resistance (NDR). This work clarifies memory effects in molecular electronics.
Area of Science:
- Molecular electronics
- Condensed matter physics
- Physical chemistry
Background:
- Nonlinear charge transport phenomena, including hysteresis and negative differential resistance (NDR), are increasingly observed in redox molecular junctions.
- Understanding these phenomena is crucial for developing advanced molecular electronic devices.
Purpose of the Study:
- To present and discuss theoretical models for redox molecular junctions that explain nonlinear charge transport.
- To account for observed hysteresis and hysteretic negative differential resistance (NDR).
Main Methods:
- Development of theoretical models incorporating at least two conduction channels (slow and fast).
- Application of Marcus' theory of heterogeneous electron transfer (ET) to analyze conduction regimes.
- Investigation of charge localization, medium polarization, and conformational changes.
- Extension of theory to analyze single sweep cycles, ensemble averages, and quantum effects.
Main Results:
- Models identify distinct conduction regimes governed by charge localization and stabilization mechanisms.
- Demonstration that charge localization can decouple current dynamics from voltage sweep rates, causing hysteresis.
- Identification of a common origin for irreversibility in current-voltage cycles and standard voltammetry.
- Derivation of threshold voltage sweep rates for observed phenomena.
- Analysis of quantum effects in the fast transport channel.
Conclusions:
- Theoretical models successfully explain nonlinear transport phenomena like hysteresis and NDR in redox molecular junctions.
- Charge localization, influenced by environmental factors, is key to memory effects and hysteresis.
- The presented framework provides insights into the behavior of molecular junctions and their potential applications.
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