Charge transport through oligoarylene self-assembled monolayers

Interplay of molecular organization, metal-molecule interactions, and electronic structure

Christian Grave, Chad Risko, Andrey Shaporenko, Yiliang Wang, Colin Nuckolls, Mark A Ratner, Maria Anita Rampi, Michael Zharnikov

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

The electrical properties of two molecular wires-a novel aryl moiety, 6-(5-pyridin-2-ylpyrazin-2-yl)pyridinc-3-thiol (PPPT), and the well studied 1,1;4′,1"-terphenyl-4-thiol (TPT)-organized in self-assembled monolayers (SAMs) are measured using metalmolecule-metal (MMM) mercury-drop junctions. Current measured at the same bias voltage through PPPT is found to be more than one order of magnitude lower than through TPT. To interpret and understand these results, characterization of the structure, organization of the SAMs, and theoretical analyses of the molecular systems are discussed. X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS) indicate that although PPPl' forms high-quality SAMs on both Au and Ag substrates, it exhibits a lower packing density (by 20 %) and less oricntational order than TPT. In addition, electronic structure calculations with density functional theory (DFT) reveal that the electron-withdrawing nitrogen atoms in the PPPT aryl backbone stabilize the valence molecular electronic structure rind pull negative charge from the thiol sulfur. This behavior can influence both charge-injection barriers and metal-molecule binding interactions in the MMM junctions. The current-voltage data are interpreted on the basis of a hole-tunneling, through-bond mechanism. Conductance analysis through a model for off-resonant tunneling transport suggests that a comparatively small difference in the charge-injection barrier can explain the factor of ten difference in observed conduction.

Original languageEnglish
Pages (from-to)3816-3828
Number of pages13
JournalAdvanced Functional Materials
Volume17
Issue number18
DOIs
Publication statusPublished - Dec 17 2007

Fingerprint

Self assembled monolayers
Sulfhydryl Compounds
thiols
Electronic structure
Charge transfer
Charge injection
Metals
terphenyls
electronic structure
Molecules
metals
X ray absorption near edge structure spectroscopy
Molecular electronics
molecules
Resonant tunneling
Mercury (metal)
interactions
Bias voltage
Molecular structure
Density functional theory

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Materials Science(all)
  • Condensed Matter Physics
  • Physics and Astronomy (miscellaneous)

Cite this

Charge transport through oligoarylene self-assembled monolayers : Interplay of molecular organization, metal-molecule interactions, and electronic structure. / Grave, Christian; Risko, Chad; Shaporenko, Andrey; Wang, Yiliang; Nuckolls, Colin; Ratner, Mark A; Rampi, Maria Anita; Zharnikov, Michael.

In: Advanced Functional Materials, Vol. 17, No. 18, 17.12.2007, p. 3816-3828.

Research output: Contribution to journalArticle

Grave, Christian ; Risko, Chad ; Shaporenko, Andrey ; Wang, Yiliang ; Nuckolls, Colin ; Ratner, Mark A ; Rampi, Maria Anita ; Zharnikov, Michael. / Charge transport through oligoarylene self-assembled monolayers : Interplay of molecular organization, metal-molecule interactions, and electronic structure. In: Advanced Functional Materials. 2007 ; Vol. 17, No. 18. pp. 3816-3828.
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