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Proceedings Paper

Novel bright small molecular white OLEDs
Author(s): Chang-Hwan Kim; Joseph Shinar
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Paper Abstract

Bright [indium tin oxide (ITO)]/[N,N'-diphenyl-N,N'-bis(1- naphthyl-phenyl)-1,1'-biphenyl-4,4'-diamine(NPB)]/[2 wt.% perylene-doped 4,4'-bis(9-carbazolyl) biphenyl (CBP)]/[2-(4- biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (Bu- PBD)]/[2 wt.% 4-(dicyano-methylene)-2-methyl-6-(p-dimethyl aminostyryl)-4H-pyran (DCM1)-doped tris-(8-hydroxy quinoline) Al(Alq3)]/CsF/Al OLEDS are described. The electroluminescence (EL) spectra consist of blue and green bands at 453, 487, and 524 nm due to perylene and a red band at 600 nm due to DCM1, i.e., the emission zones are completely separated by the Bu-PBD. As the thickness of the NPB and perylene: CBP layers increases and that of the DCM1:alq3 layer decreases the intensity of the perylene emission increases strongly relative to the DCM1 emission. For 350 A thick NPB, 350 A thick perylene: CBP, 100 A Bu- PBD, and 150 A DCM1:Alq3, the onset voltage is 6.5 V, the brightness reaches 3750 Cd/m2 at 20 V, the efficiency is 2.4 Cd/A at 19V, and the (x,y) CIE coordinates are well within the white region. However, as the bias is increased the intensity of the perylene emission increases relative to the DCM1 emission, so (x,y) evolves from (0.42, 0.35) at 14V to (0.29, 0.32) at 21V. Both the layer thickness- and bias-dependence are believed to result from changes in the recombination zone and in the field-and cathode-mirror- induced quenching of the DCM1 singlet excitons.

Paper Details

Date Published: 27 February 2002
PDF: 8 pages
Proc. SPIE 4464, Organic Light-Emitting Materials and Devices V, (27 February 2002); doi: 10.1117/12.457493
Show Author Affiliations
Chang-Hwan Kim, U.S. Dept. of Energy and Iowa State Univ. (United States)
Joseph Shinar, U.S. Dept. of Energy and Iowa State Univ. (United States)

Published in SPIE Proceedings Vol. 4464:
Organic Light-Emitting Materials and Devices V
Zakya H. Kafafi, Editor(s)

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