Observation of filled states at the Fermi-level in alkali-metal intercalated organic films: Dependence on substrate work function

N. Koch, F. Jäckel, J. Ghijsen, M. C. Rojas, M. Grioni, J. P. Rabe, R. L. Johnson, A. Kahn, J. J. Pireaux

Research output: Contribution to journalArticle

3 Scopus citations

Abstract

We present ultraviolet photoelectron spectroscopy studies on alkali metal-intercalated thin films of electroluminescent p-sexiphenyl (6P) and the organic hole transporting material N,N′-bis-(1-naphthyl)-N,N′- diphenyl1-1,1-biphenyl1-4,4′-diamine (α-NPD). The formation of new occupied electronic states in the otherwise empty energy gap of 6P and α-NPD is observed, accompanied by a significant shift of the Fermi-level. Depending on the work function φ of the substrate used for the organic thin films, we observe two different scenarios at low intercalation levels: the new electronic states are observed at (and even above) EF for high φ substrates, whereas they are observed below EF for low φ substrates. At high intercalation levels, all the states are observed below EF. The observation of states at and above EF is attributed to a lack of thermodynamic equilibrium across the organic thin film.

Original languageEnglish (US)
Pages (from-to)495-498
Number of pages4
JournalJournal of Electron Spectroscopy and Related Phenomena
Volume144-147
DOIs
StatePublished - Jun 2005

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Radiation
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Spectroscopy
  • Physical and Theoretical Chemistry

Keywords

  • Alkali metals
  • Organic materials
  • Photoelectron spectroscopy
  • Thin films

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