Abstract
The transport properties of a junction consisting of small donor-acceptor molecules bound to Au electrodes are studied and understood in terms of its hybrid donor-acceptor-electrode interfaces. A newly synthesized donor-acceptor molecule consisting of a bithiophene donor and a naphthalenediimide acceptor separated by a conjugated phenylacetylene bridge and a nonconjugated end group shows rectification in the reverse polarization, behavior opposite to that observed in mesoscopic p-n junctions. Solution-based spectroscopic measurements demonstrate that the molecule retains many of its original constituent properties, suggesting a weak hybridization between the wave functions of the donor and acceptor moieties, even in the presence of a conjugated bridge. Differential conductance measurements for biases as high as 1.5 V are reported and indicate a large asymmetry in the orbital contributions to transport arising from disproportionate electronic coupling at anode-donor and acceptor-cathode interfaces. A semi-empirical single Lorentzian coherent transport model, developed from experimental data and density functional theory based calculations, is found to explain the inverse rectification.
Original language | English (US) |
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Pages (from-to) | 9256-9263 |
Number of pages | 8 |
Journal | ACS nano |
Volume | 5 |
Issue number | 11 |
DOIs | |
State | Published - Nov 22 2011 |
Keywords
- donor-acceptor molecule
- inverse rectification
- molecular diode
- single-molecule conductance
ASJC Scopus subject areas
- General Engineering
- General Physics and Astronomy
- General Materials Science