Oxygen effect on the interface formation between calcium and a polyfluorene film

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)22_Publication in policy or professional journal

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Author(s)

  • L. S. Liao
  • L. F. Cheng
  • M. K. Fung
  • S. T. Lee
  • M. Inbasekaran
  • E. P. Woo
  • W. W. Wu

Detail(s)

Original languageEnglish
Pages (from-to)10004-10007
Journal / PublicationPhysical Review B - Condensed Matter and Materials Physics
Volume62
Issue number15
Publication statusPublished - 15 Oct 2000

Abstract

The effect of oxygen on the interface formation between Ca electrode and a poly (9,9-dioctylfluorene) (PFO) film was investigated using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The XPS results indicated that strong interaction between Ca and C occurred and the lowest unoccupied molecular orbitals (LUMO's) of PFO were affected upon a submonolayer Ca deposition. After O2 exposure, the interaction between Ca and C was reduced and the LUMO of PFO was partially recovered. However, too much O2 exposure (> 105 L in our experiments) would again deteriorate the original LUMO and result in a very wide band gap, which might be due to changes in the chemical structures of PFO in the Ca-doped region after extra O2 exposure. The UPS results confirmed that the deformed UPS spectrum after Ca deposition can be partially recovered and the Ca-induced bipolaron states in the former forbidden energy gap could be removed upon O2 exposure.

Citation Format(s)

Oxygen effect on the interface formation between calcium and a polyfluorene film. / Liao, L. S.; Cheng, L. F.; Fung, M. K.; Lee, C. S.; Lee, S. T.; Inbasekaran, M.; Woo, E. P.; Wu, W. W.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 62, No. 15, 15.10.2000, p. 10004-10007.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)22_Publication in policy or professional journal