AVS 52nd International Symposium
    Electronic Materials and Processing Tuesday Sessions
       Session EM-TuP

Paper EM-TuP15
Photo- and Electro-Luminescence Studies of Highly Alkyl-Substituted Templated Bis(8-Hydroxyquinoline) Derivatives for Organic Light Emitting Diodes

Tuesday, November 1, 2005, 4:00 pm, Room Exhibit Hall C&D

Session: Electronic Materials and Processing Poster Session
Presenter: R.D. Torres, University of Florida
Authors: R.D. Torres, University of Florida
P.H. Holloway, University of Florida
J.R. Reynolds, University of Florida
M. Albrecht, RWTH Aachen, Germany
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Aluminum tris(8-hydroxyquinoline) (Alq@sub 3@) is the most widely used electon transport and emissive material in organic light emitting diodes (OLEDs). Alq@sub 3@ is thermally and morphologically stable when vacuum deposited. The molecule is shaped to avoid exciplex formation, serves as a good green (@lambda@@sub max@ = 520 nm) emitter with excellent electron-transport properties, and the bandgap can be modified by attaching electron withdrawing/donating organic groups. In this study we have used solution and thin-film photoluminescence (PL) to characterize the emissive properties of new Alq@sub 3@ type derivatives: tetra-decyl-substituted ethylene-linked bis(8-hydroxyquinoline) (BHQ) ligands. The effects of different templating cations (K@super +@, NH@sub 4@@super +@, Rb@super +@, Cs@super +@) on optical emission from these complexes [(ligand)@sub 3@Al@sub 2@ and (ligand)@sub 3@Ga@sub 2@] were investigated. Solutions were prepared using only the complexes, or using the complexes with various molar concentrations of poly(methyl methacrylate) or polystyrene. The ratio of PMMA or PS was varied relative to the polymer repeat unit, and compared to similarly prepared Alq@sub 3@ solutions. Thin films were made by spin coating on glass substrates. The samples were excited with a 350 nm excitation, and spectra were recorded from 400 to 650 nm. Electroluminescent devices with structures of glass/ITO/PEDOT-PSS HTL/BHQ complexes ETL/LiF/Al were prepared. The current-voltage-luminescence characteristics of these devices were observed. These complexes show promise as Alq@sub 3@ derivatives that can be processed by methods other than vacuum evaporation.