Dresden 2003 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 20: POSTER A

CPP 20.73: Poster

Montag, 24. März 2003, 19:00–21:00, ZEU/250

STRUCTURAL AND OPTOELECTRONIC PROPERTIES OF THE BLUE LUMINESCENT δ-PHASE OF ALQ₃ — •Anton Georg Mückl¹, Michael Cölle¹, Jürgen Gmeiner¹, Stefan Forero¹, and Wolfgang Brütting² — ¹Experimental Physics II, University of Bayreuth, D-95440 Bayreuth, Germany — ²Experimental Physics IV, University of Augsburg, D-86135 Augsburg, Germany

Tris(8-hydroxyquinolinato)aluminium(III) (Alq₃) stands as one of the most successful materials used in organic light emitting devices for display applications. It is well-known that depending on the mutual orientation of the hydroxyquinoline ligands, Alq₃ can occur in two different stereoisomers: meridional and facial, however, so far all existing phases (α, β and γ) have been found to consist of the meridional isomer. Recently, we have reported on a new crystalline phase of Alq₃ (δ-Alq₃) exhibiting strongly blue-shifted fluorescence. Its significantly different optical properties have been tentatively ascribed to the isomery of the Alq₃ molecule. Here we will present an in-depth characterization of the different phases of Alq₃ by combining thermal, structural and vibrational analysis. These data provide unambiguous evidence for the existence of the facial isomer in the blue luminescent δ-phase of Alq₃. Furthermore, an efficient way to fabricate blue luminescent Alq₃ in large amounts has been found. These results will be correlated with the optoelectronic properties of Alq₃ and Alq₃-based thin film electroluminescent devices.