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Proceedings Paper

Comparison of device performance using various metal quinolates as the host for a guest-host active layer
Author(s): Lisa A. Crisafulli; Hideyuki Murata; Charles D. Merritt; Zakya H. Kafafi
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Paper Abstract

We present a study that focuses on a comparison of the absolute photoluminescence quantum efficiency ((phi) pl) with the electroluminescence quantum efficiency ((eta) el) using a guest-host active layer. We also report the luminous power efficiency of devices based on this same emissive layer. The active layer consists of a series of metal quinolates used as the host for the dopant rubrene. We find that rubrene doping enhances the (phi) pl of the metal quinolate host materials, tris(8-hydroxyquinolinato) gallium III (Gaq3), tris(8-hydroxyquinolinato) aluminum III (Alq3), and tris(4-methyl-8-hydroxyquinolinato) aluminum III (Almq3), from 0.13, 0.25, and 0.42, respectively, to approximately 1.0 for all metal quinolates. This is achieved by efficient Forster energy transfer from host to guest molecules. We also find that doping enhances the (eta) el of devices using Gaq3 or Alq3 as the active layer from 0.6% and 1.0%, respectively, to 2.2% for both hosts when measured at a current density of 100 A/m2. The (eta) el of devices based on Almq3 increases from 1.6% to 2.9% upon doping with rubrene. At a brightness of 100 cd/m2, the luminous power efficiency of devices based on the metal quinolates increases from 1.0 lm/W, 0.99 lm/W, and 2.1 lm/W to 3.6 lm/W, 4.0 lm/W, and 3.8 lm/W for Gaq3, Alq3, and Almq3, respectively, when doped with an optimized concentration of rubrene. These enhancements are attributed to carrier trapping followed by direct recombination on the rubrene dopant as well as efficient energy transfer from the host to rubrene.

Paper Details

Date Published: 17 December 1999
PDF: 8 pages
Proc. SPIE 3797, Organic Light-Emitting Materials and Devices III, (17 December 1999); doi: 10.1117/12.372740
Show Author Affiliations
Lisa A. Crisafulli, Naval Research Lab. (United States)
Hideyuki Murata, Naval Research Lab. (United States)
Charles D. Merritt, Naval Research Lab. (United States)
Zakya H. Kafafi, Naval Research Lab. (United States)

Published in SPIE Proceedings Vol. 3797:
Organic Light-Emitting Materials and Devices III
Zakya H. Kafafi, Editor(s)

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