Transistor configuration yields energy level control in protein-based junctions

The incorporation of proteins as functional components in electronic junctions has received much interest recently due to their diverse bio-chemical and physical properties. However, information regarding the energies of the frontier orbitals involved in their electron transport (ETp) has remained e...

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Bibliographic Details
Published in:Nanoscale 2018-11, Vol.10 (46), p.21712-21720
Main Authors: Kayser, Ben, Fereiro, Jerry A, Guo, Cunlan, Cohen, Sidney R, Sheves, Mordechai, Pecht, Israel, Cahen, David
Format: Article
Language:English
Subjects:
Azurin - chemistry
Copper
Copper - chemistry
Electrode materials
Electrodes
Electron transfer
Electron Transport
Energy levels
Gold - chemistry
Molecular orbitals
Organic chemistry
Oxidation-Reduction
Physical properties
Proteins
Quantum Theory
Resistance
Transistors, Electronic
Work functions
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Summary:The incorporation of proteins as functional components in electronic junctions has received much interest recently due to their diverse bio-chemical and physical properties. However, information regarding the energies of the frontier orbitals involved in their electron transport (ETp) has remained elusive. Here we employ a new method to quantitatively determine the energy position of the molecular orbital, nearest to the Fermi level (EF) of the electrode, in the electron transfer protein Azurin. The importance of the Cu(ii) redox center of Azurin is demonstrated by measuring gate-controlled conductance switching which is absent if Azurin's copper ions are removed. Comparing different electrode materials, a higher conductance and a lower gate-induced current onset is observed for the material with smaller work function, indicating that ETp via Azurin is LUMO-mediated. We use the difference in work function to calibrate the difference in gate-induced current onset for the two electrode materials, to a specific energy level shift and find that ETp via Azurin is near resonance. Our results provide a basis for mapping and studying the role of energy level positions in (bio)molecular junctions.
ISSN:2040-3364
2040-3372
DOI:10.1039/c8nr06627b