Odd-even effects in charge transport across n-alkanethiolate-based SAMs

J Am Chem Soc. 2014 Dec 3;136(48):16919-25. doi: 10.1021/ja509436k. Epub 2014 Nov 20.

Abstract

This paper compares rates of charge transport across self-assembled monolayers (SAMs) of n-alkanethiolates having odd and even numbers of carbon atoms (nodd and neven) using junctions with the structure M(TS)/SAM//Ga2O3/EGaIn (M = Au or Ag). Measurements of current density, J(V), across SAMs of n-alkanethiolates on Au(TS) and Ag(TS) demonstrated a statistically significant odd-even effect on Au(TS), but not on Ag(TS), that could be detected using this technique. Statistical analysis showed the values of tunneling current density across SAMs of n-alkanethiolates on Au(TS) with nodd and neven belonging to two separate sets, and while there is a significant difference between the values of injection current density, J0, for these two series (log|J0Au,even| = 4.0 ± 0.3 and log|J0Au,odd| = 4.5 ± 0.3), the values of tunneling decay constant, β, for nodd and neven alkyl chains are indistinguishable (βAu,even = 0.73 ± 0.02 Å(-1), and βAu,odd= 0.74 ± 0.02 Å(-1)). A comparison of electrical characteristics across junctions of n-alkanethiolate SAMs on gold and silver electrodes yields indistinguishable values of β and J0 and indicates that a change that substantially alters the tilt angle of the alkyl chain (and, therefore, the thickness of the SAM) has no influence on the injection current density across SAMs of n-alkanethiolates.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alkanes / chemical synthesis
  • Alkanes / chemistry*
  • Electron Transport
  • Gold / chemistry
  • Silver / chemistry
  • Sulfhydryl Compounds / chemical synthesis
  • Sulfhydryl Compounds / chemistry*

Substances

  • Alkanes
  • Sulfhydryl Compounds
  • Silver
  • Gold