Molecular Junctions: Control of the Energy Gap Achieved by a Pinning Effect

Colin Van Dyck*, Mark A. Ratner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


Single-molecule junctions are the constitutive components of molecular electronics circuits. For any potential application, the energy gap in the junction, i.e., the accumulated energy difference between the electrode Fermi level and the two frontier energy levels of the molecule, is a key property. Here, using the nonequilibrium Green's function coupled to the density functional theory framework (NEGF-DFT) method, we show that the gap of the molecule inserted between electrodes can differ largely from the gap of the same molecule, at the isolated level. It can be widely compressed by tuning the alignment mechanism at each metal/molecule interface. In the context of molecular rectification, we show that this mechanism relates to the pinning effect. We discuss the different parameters affecting the compression of the gap and its efficiency. Interestingly, we find that the structure both of the molecule and of the anchoring group plays an important role. Finally, we investigate the evolution of these features out-of-equilibrium.

Original languageEnglish (US)
Pages (from-to)3013-3024
Number of pages12
JournalJournal of Physical Chemistry C
Issue number5
StatePublished - Feb 9 2017

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • General Energy
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films


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