Implications of an Electron-Hopping Model for Charge Transport through Donor−Bridge−Acceptor Assemblies Connected to Metal Electrodes
| Autor: | Carol Creutz, Stephen W. Feldberg, N. Sutin, Bruce S. Brunschwig |
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| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | The Journal of Physical Chemistry B. 108:12092-12102 |
| ISSN: | 1520-5207 1520-6106 |
| DOI: | 10.1021/jp048133k |
| Popis: | An electron-hopping model for electrode-to-electrode charge transport through donor-bridge-acceptor assemblies (J. Phys. Chem. B 2003, 107, 10687) is further developed by detailed electrostatic analysis of the assembly and treatment of the steady-state kinetics. Charge transport between the two electrodes proceeds via the D−B−A bridges: D transfers an electron to A through the bridge. The newly formed D+ and A- are then rapidly reduced and oxidized, respectively, at the electrodes giving rise to a steady state in which the current depends on the rate of electron transfer from D to A. The driving force dependence of the nuclear factor for the D to A electron transfer results in the current through the D−B−A bridge increasing with applied voltage (positive differential conductance) in the normal free-energy region but decreasing in the inverted region (negative differential conductance). The electronic factors can be manipulated by changing the separations between the electrodes and DBA or the length of B or by changing the nature of the bridge material. Decreasing the electronic factor for D to A electron transfer decreases the flux at a given applied voltage in the normal region, but the effect is much greater in the inverted region. Possible parallel tunneling and electron hopping mechanisms that could contribute to the current and interfere with the region of negative differential resistance are analyzed in detail. For the coupled electron-transfer sequence considered here, changing electronic factors result in dramatic shifts of the reaction profile. |
| Databáze: | OpenAIRE |
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