Regensburg 2004 – wissenschaftliches Programm
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SYOH: Organic and Hybrid Systems for Future Electronics
SYOH 5: Poster
SYOH 5.88: Poster
Donnerstag, 11. März 2004, 18:00–21:00, B
Structural and Optoelectronic Properties of Different Phases of the Electroluminescent Material Alq3 — •Michael Cölle1, Christoph Gärditz1, Jürgen Gmeiner1, Stefan Forero1, and Wolfgang Brütting1,2 — 1Experimental Physics II, University of Bayreuth, 95440 Bayreuth, Germany — 2Experimental Physics IV, University of Augsburg, 86135 Augsburg, Germany
Tris(8-hydroxyquinolinato)aluminium(III) (Alq3) stands as one of the most successful materials used in OLEDs for display applications. Although the partly nanocrystalline character of evaporated films used in these applications is known, so far comparatively few investigations have been devoted to the crystalline state of this material. Another still unresolved issue concerns the isomery of the Alq3 molecule. From theory is well-known that Alq3 can occur in two different geometrical isomers: meridional and facial. However, until recently all existing phases ( α, β and γ) have been found to consist of the meridional isomer. Recently we have reported a new crystalline phase of Alq3 (δ-Alq3) exhibiting strongly blue-shifted fluorescence. Its significantly different optical properties have been tentatively discussed in terms of the isomery of the Alq3 molecule.
In this contribution we will present an in-depth characterisation of the different phases of Alq3 by combining thermal, structural and vibrational analysis. These data provide the first unambigous evidence for the existence of the facial isomer in the blue-luminescent δ-phase of Alq3. These results will be correlated to the optoelectronic properties of Alq3 and Alq3-based thin film electroluminescent devices.