Investigation of the transition voltage spectra of molecular junctions considering frontier molecular orbitals and the asymmetric coupling effect

Gunuk Wang, Yonghun Kim, Seok In Na, Yung Ho Kahng, Jamin Ku, Sungjun Park, Yun Hee Jang, Dong Yu Kim, Takhee Lee

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35 Citations (Scopus)

Abstract

This study experimentally and theoretically investigated the characteristics of transition voltage spectroscopy (TVS) with different asymmetric coupling in molecular junctions that were formed by several alkyl- and oligoacene-based molecules. On the basis of the analysis of a statistically significant number of device data (a total of ∼300 devices and ∼880 TVS data), we confirmed that the minimum point appearing in the Fowler-Nordheim (F-N) plot of the current-voltage characteristics depended linearly on the energy offset between the Fermi energy of the electrodes and the highest-occupied molecular orbital (HOMO) energy level of the molecular channel. We also observed that the slope of the log(I)-log(V) plot in molecular junctions changed sequentially. In addition, we extended a coherent molecular model by considering both the HOMO and the lowest-unoccupied molecular orbital (LUMO) levels of molecules and developed more comprehensive explanations for the TVS characteristics that are influenced by the asymmetric coupling, molecular length, and molecular orbital as well as for the sequential change in the slope of the log(I)-log(V) plot in molecular junctions.

Original languageEnglish
Pages (from-to)17979-17985
Number of pages7
JournalJournal of Physical Chemistry C
Volume115
Issue number36
DOIs
Publication statusPublished - 2011 Sep 15
Externally publishedYes

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ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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