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Proceedings Paper

Changes in electronic structure of 8-hydroxyquinoline aluminum/Al interface by insertion of thin electron injection layers
Author(s): Tomohiko Mori; Motofumi Suzuki; Shizuo Tokito; Yasunori Taga
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Paper Abstract

The electronic structures of 8-hydroxyquinoline aluminum (Alq3)/electron injection layer/Al interfaces, used in organic electroluminescent devices, were measured by ultraviolet photoelectron spectroscopy (UPS). LiF and alkaline earth fluorides (CaF2, SrF2 and BaF2) were used as an electron injection layer. Shifts of the highest occupied molecular orbital (HOMO) level and the vacuum level of Alq3 layer due to the insertion of the fluorides were observed. These shifts indicate that the alkaline earth fluoride layers as well as the LiF layer at the Alq3/Al interface reduce the barrier height for electron injection from the Al to Alq3. The reduction of the barrier height is consistent with the driving voltage in the organic EL device in which these fluorides are used as the electron injection layers. We believe that lowering in the driving voltage in organic EL devices with the thin insulator layers, such as LiF and alkaline earth fluorides, is attributable to the reduction of the barrier height.

Paper Details

Date Published: 17 December 1999
PDF: 8 pages
Proc. SPIE 3797, Organic Light-Emitting Materials and Devices III, (17 December 1999); doi: 10.1117/12.372732
Show Author Affiliations
Tomohiko Mori, Toyota Central Research and Development Labs., Inc. (Japan)
Motofumi Suzuki, Toyota Central Research and Development Labs., Inc. (Japan)
Shizuo Tokito, Toyota Central Research and Development Labs., Inc. (Japan)
Yasunori Taga, Toyota Central Research and Development Labs., Inc. (Japan)


Published in SPIE Proceedings Vol. 3797:
Organic Light-Emitting Materials and Devices III
Zakya H. Kafafi, Editor(s)

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