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Inverse Rectification in Donor–Acceptor Molecular Heterojunctions

TitleInverse Rectification in Donor–Acceptor Molecular Heterojunctions
Publication TypeJournal Article
Year of Publication2011
AuthorsYee, Shannon K., Jibin Sun, Pierre Darancet, Don T. Tilley, Arun Majumdar, Jeffrey B. Neaton, and Rachel A. Segalman
JournalACS Nano
Date PublishedNovember 2011
ISBN Number1936-0851

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.

Short TitleACS Nano