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Proceedings Paper

Improvement in the environmental stability of tris(8-hydroxyquinoline) aluminum by substitution of sulphonic acid in 8-hydroxyquinoline ligand
Author(s): V. Arul Lenus Roy; Chung Yin Kwong; Aleksandra B. Djurisic; Ramachandra B. Pode; T. K. Gundu Rao; Wai Kin Chan
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Paper Abstract

Tris (8-hydroxyquinoline) aluminum (Alq3) is a commonly used electron transporting and/or light emitting material in organic light emitting diodes (OLEDs). However, it is well known that Alq3 is very sensitive to atmosphere exposure and that photoluminescence of Alq3 films decreases with the time of atmosphere exposure. Degradation is also a serious problem in Alq3 based OLEDs. Several degradation mechanisms have been identified in these devices, including formation of unstable cationic species due to passage of holes. Therefore, there is lots of interest in improving the stability of Alq3. We have synthesized Tris (8-hydroxyquinoline-5 sulphonic acid) aluminum [Al(qS)3] in order to improve the stability. We performed electron spin resonance measurements on Alq3 and Al(qS)3 powders. Unlike Alq3 which exhibited strong ESR signal, Al(qS)3 produced no detectable ESR signal indicating absence of free radicals in this material. To test the environmental stability of Al(qS)3 films, we have performed photoluminescence (PL) measurements in humid air at different temperatures and found that Al(qS)3 exhibits improved stability. After comparing the stability of Alq3 and Al(qS)3 thin films, fabrication of the light emitting diodes with Al(qS)3 emitting layer was attempted in order to compare the performance with Alq3 based devices.

Paper Details

Date Published: 16 February 2004
PDF: 8 pages
Proc. SPIE 5214, Organic Light-Emitting Materials and Devices VII, (16 February 2004); doi: 10.1117/12.503009
Show Author Affiliations
V. Arul Lenus Roy, Univ. of Hong Kong (Hong Kong China)
Chung Yin Kwong, Univ. of Hong Kong (Hong Kong China)
Aleksandra B. Djurisic, Univ. of Hong Kong (Hong Kong China)
Ramachandra B. Pode, Nagpur Univ. (India)
T. K. Gundu Rao, Indian Institute of Technology Mumbai (India)
Wai Kin Chan, Univ. of Hong Kong (Hong Kong China)

Published in SPIE Proceedings Vol. 5214:
Organic Light-Emitting Materials and Devices VII
Zakya H. Kafafi; Paul A. Lane, Editor(s)

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