Preparation and characterization of 4'-donor substituted stilbene-4-thiolate monolayers and their influence on the work function of gold

M. Malicki, Zelei Guan, Sieu D. Ha, Georg Heimel, Stephen Barlow, Mariacristina Rumi, Antoin Kahn, Seth R. Marder

Research output: Contribution to journalArticle

23 Scopus citations

Abstract

Self-assembled monolayers of E-stilbene-4-thiolate (SAM1), E-40-(ethoxy)stilbene-4-thiolate (SAM2), and E-40- (dimethylamino)stilbene-4- thiolate (SAM3) on Au(111) have been obtained from reaction of ethanol solutions of the corresponding S-acetyl derivatives with gold substrates. A combination of X-ray photoelectron spectroscopy, ellipsometry, and infrared reflection absorption spectroscopy indicates that the monolayers are dense (ca. 3.3× 10 14 molecules/cm 2) and that the long molecular axes of the thiolates are approximately perpendicular to the surface. Ultraviolet photoelectron spectroscopy shows that formation of these monolayers decreases the work function of pristine Au by 0.9-1.3 eV, in part due to a bond dipole of ca. 4.4 D/molecule formed upon adsorption and partly due to the molecular dipole moment arising from the 40-π-donor substituents. However, the extent of the work function variation between SAM1, 2, and 3 is smaller than anticipated from purely electrostatic considerations.

Original languageEnglish (US)
Pages (from-to)7967-7975
Number of pages9
JournalLangmuir
Volume25
Issue number14
DOIs
StatePublished - Jul 21 2009

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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