Electronic structure of 8-hydroxyquinoline aluminum (Alq3) / metal interfaces studied by UV photoemission

H. Ishii, D. Yoshimura, K. Sugiyama, S. Narioka, Y. Hamatani, I. Kawamoto, Takafumi Miyazaki, Y. Ouchi, K. Seki

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

The electronic structures of tris(8-hydroxyquinoline) aluminum (Alq3) / metal (Au, Al) interfaces as a model interface of organic electroluminescent (EL) devices were investigated by ultraviolet photoemission spectroscopy (UPS). We found abrupt shifts of the vacuum level of ca. 1 eV at the interfaces in contrast to the traditional assumption with a common vacuum level at the interface. The shift indicates the formation of interfacial dipole with the metal side negatively charged. At Alq3 / Al interface, the estimated energy position of the lowest unoccupied molecular orbital (LUMO) was very close to the Fermi level of the substrate metal, corresponding to the electron-injecting nature of the interface. This is in contrast to the poor electron-injecting character expected by assuming a common vacuum level where Fermi level of the substrate should be around the center of the gap. The electronic structure of Alq3 as a solid is also discussed in comparison with the results by semi-empirical molecular orbital calculation.

Original languageEnglish
Pages (from-to)1389-1390
Number of pages2
JournalSynthetic Metals
Volume85
Issue number1-3
Publication statusPublished - Mar 15 1997
Externally publishedYes

Fingerprint

Oxyquinoline
Photoemission
Aluminum
Electronic structure
photoelectric emission
Metals
Vacuum
Molecular orbitals
electronic structure
Fermi level
aluminum
metals
Luminescent devices
Orbital calculations
Electrons
Substrates
Photoelectron spectroscopy
Ultraviolet spectroscopy
vacuum
molecular orbitals

Keywords

  • Organic semiconductors based on conjugated molecules
  • Organic/inorganic interface
  • Photoelectron spectroscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Materials Chemistry
  • Polymers and Plastics

Cite this

Ishii, H., Yoshimura, D., Sugiyama, K., Narioka, S., Hamatani, Y., Kawamoto, I., ... Seki, K. (1997). Electronic structure of 8-hydroxyquinoline aluminum (Alq3) / metal interfaces studied by UV photoemission. Synthetic Metals, 85(1-3), 1389-1390.

Electronic structure of 8-hydroxyquinoline aluminum (Alq3) / metal interfaces studied by UV photoemission. / Ishii, H.; Yoshimura, D.; Sugiyama, K.; Narioka, S.; Hamatani, Y.; Kawamoto, I.; Miyazaki, Takafumi; Ouchi, Y.; Seki, K.

In: Synthetic Metals, Vol. 85, No. 1-3, 15.03.1997, p. 1389-1390.

Research output: Contribution to journalArticle

Ishii, H, Yoshimura, D, Sugiyama, K, Narioka, S, Hamatani, Y, Kawamoto, I, Miyazaki, T, Ouchi, Y & Seki, K 1997, 'Electronic structure of 8-hydroxyquinoline aluminum (Alq3) / metal interfaces studied by UV photoemission', Synthetic Metals, vol. 85, no. 1-3, pp. 1389-1390.
Ishii H, Yoshimura D, Sugiyama K, Narioka S, Hamatani Y, Kawamoto I et al. Electronic structure of 8-hydroxyquinoline aluminum (Alq3) / metal interfaces studied by UV photoemission. Synthetic Metals. 1997 Mar 15;85(1-3):1389-1390.
Ishii, H. ; Yoshimura, D. ; Sugiyama, K. ; Narioka, S. ; Hamatani, Y. ; Kawamoto, I. ; Miyazaki, Takafumi ; Ouchi, Y. ; Seki, K. / Electronic structure of 8-hydroxyquinoline aluminum (Alq3) / metal interfaces studied by UV photoemission. In: Synthetic Metals. 1997 ; Vol. 85, No. 1-3. pp. 1389-1390.
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