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A molecular switch based on potential-induced changes of oxidation state
Fan Chen1, Jin He, Colin Nuckolls
1Department of Physics and Astronomy, Columbia University, NY, USA.
Nano Letters
|March 10, 2005
Summary
Conductance of a hepta-aniline oligomer significantly increases upon oxidation. This molecular electronic device exhibits negative differential resistance in acidic electrolytes, linked to surface potential changes.
Area of Science:
- Molecular electronics
- Electrochemistry
- Conductance measurements
Background:
- Aniline oligomers are promising molecular wires.
- Controlling molecular conductance via electrochemical methods is crucial for device applications.
Purpose of the Study:
- To measure the conductance of a hepta-aniline oligomer under potential control.
- To investigate the single-molecule current-voltage characteristics.
- To understand the relationship between electrochemical state and molecular electronic behavior.
Main Methods:
- Attaching a hepta-aniline oligomer to gold electrodes.
- Applying potential control in an electrolyte solution.
- Measuring conductance and current-voltage characteristics.
Main Results:
- A fifteen-fold increase in conductance (5.3+/-0.4 nS) was observed upon oxidation from leucoemeraldine to emeraldine salt.
- Linear current-voltage characteristics were observed in toluene.
- Negative differential resistance was observed in an acidic electrolyte.
- Negative differential resistance was attributed to bias-induced modification of the local surface potential.
Conclusions:
- Electrochemical data can be directly correlated with molecular electronic behavior.
- Hepta-aniline oligomers show tunable conductance based on their oxidation state.
- Surface potential modulation plays a key role in the observed negative differential resistance in molecular devices.