Interfaces between poly(9,9-dioctylfluorene) and alkali metals as affected by molecular weight and oxygen

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

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Author(s)

  • M. K. Fung
  • S. L. Lai
  • S. N. Bao
  • J. J. O'Brien
  • M. Inbasekaran
  • W. W. Wu
  • S. T. Lee

Detail(s)

Original languageEnglish
Pages (from-to)232-238
Journal / PublicationProceedings of SPIE - The International Society for Optical Engineering
Volume4464
Publication statusPublished - 2002

Conference

TitleOrganic Light-Emitting Materials and Devices V
PlaceUnited States
CitySan Diego,CA
Period30 July - 1 August 2001

Abstract

The electronic structure of poly (9,9-dioctylfluorene) (PFO) in different molecular weights coated with alkali metals (K and Cs) has been studied by x-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). No significant differences on the electronic structures were observed for all combinations of alkali metals and PFO in different molecular weights. These metals led to low injection barrier at the K/PFO or Cs/PFO interfaces and induced bipolaron gap states in the PFO. With increasing coverage of the alkali metals, the bipolaron states and the highest-occupied molecular orbitals gradually broadened, and the two shake-up peaks of C1s XPS peaks associated with the lowest-unoccupied molecular orbitals of PFO also broadened and greatly diminished. Upon slight oxygen exposure, the two bipolaron states disappeared and the deformed features in the UPS and XPS spectra were partially recovered.

Research Area(s)

  • Alkali metals, Interface, Light-emitting diodes, Polyfluorene, Polymer

Citation Format(s)

Interfaces between poly(9,9-dioctylfluorene) and alkali metals as affected by molecular weight and oxygen. / Fung, M. K.; Lai, S. L.; Bao, S. N.; Lee, C. S.; O'Brien, J. J.; Inbasekaran, M.; Wu, W. W.; Lee, S. T.

In: Proceedings of SPIE - The International Society for Optical Engineering, Vol. 4464, 2002, p. 232-238.

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