AVS 47th International Symposium
    Organic Films and Devices Thursday Sessions
       Session OF+EL+SS-ThM

Paper OF+EL+SS-ThM10
Effect of Fluoride Layer Insertion on the Electronic Structures of Al/Organic Interfaces@footnote 1@

Thursday, October 5, 2000, 11:20 am, Room 313

Session: Organic Thin Films
Presenter: Y. Park, Korea Research Institute of Standards and Science
Authors: Y. Park, Korea Research Institute of Standards and Science
D. Kim, Hallym University, Korea
S. Cho, Korea Research Institute of Standards and Science
O. Kwon, Korea Research Institute of Standards and Science
G. Lee, Korea Research Institute of Standards and Science
E. Cho, Chonnam National University, Korea
Correspondent: Click to Email
We have investigated the electronic structures of interfaces between Al and tris-(8-hydroxyquinoline)aluminum (Alq@sub 3@), which is a prototypical organic electroluminescent (EL) material. It has been well known that the insertion of alkali metal fluoride, such as LiF, greatly enhances the EL performance and the origin of such behaviors have been controversial. We used photoelectron spectroscopy techniques including X-ray and UV photoelectron spectroscopy (XPS and UPS) as well as resonant photoemission (RPES) to probe the electronic structure change caused by the insertion of thin layer of various alkaline and alkaline earth metal fluorides between Al and Alq@sub 3@. As previously known, the presence of LiF layer enhanced gap-state formation, but even without the LiF layer, Al deposition significantly alters the electronic structures of Alq@sub 3@. While the insertion of CsF layer showed clear enhancement of the gap states, it was much less obvious for CaF@sub 2@ layer. For both materials, the RPES showed very weak resonant enhancement when excited with photons with the energy near Cs and Ca core level absorption edge. We report similar measurements for various other fluoride materials and discuss their implications. @FootnoteText@ @footnote 1@ This work was supported in part by MOST of Korea through National Research Laboratory Program and Atomic-scale Surface Science Research Center.