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Four color stacked white organic light-emitting diodes utilizing the concept of triplet harvesting

Published online by Cambridge University Press:  14 January 2011

Th. C. Rosenow ,
S. Olthof ,
S. Reineke ,
B. Lüssem  and
K. Leo
Th. C. Rosenow*
Affiliation:
Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-StraBe 1, Dresden, Germany; E-mail: Thomas.Rosenow@gmx.de
S. Olthof
Affiliation:
Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-StraBe 1, Dresden, Germany; E-mail: Selina.Olthof@iapp.de
S. Reineke
Affiliation:
Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-StraBe 1, Dresden, Germany; E-mail: Sebastian.Reineke@iapp.de
B. Lüssem
Affiliation:
Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-StraBe 1, Dresden, Germany; E-mail: Bjoern.Luessem@iapp.de
K. Leo
Affiliation:
Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-StraBe 1, Dresden, Germany; E-mail: Karl.Leo@iapp.de
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Abstract

Organic light-emitting diodes (OLEDs) are developing into a competitive alternative to conventional light sources. Nevertheless, OLEDs need further improvement in terms of efficiency and color rendering for lighting applications. Fluorescent blue emitters allow deep blue emission and high stability, while phosphorescent blue emitter still suffer from insufficient stability. The concept of triplet harvesting is the key for achieving internal quantum efficiencies up to 100 % and simultaneously benefiting from the advantages of fluorescent blue emitters. Here, we present a stacked OLED consisting of two units comprising four different emitters in total. The first unit takes advantage of the concept of triplet harvesting and combines the light emission of a fluorescent blue and a phosphorescent red emitter. The second unit emits light from a single emission layer consisting of a matrix doped with phosphorescent green and yellow emitters. With this approach, we reach white color coordinates close to the standard illuminant A and a color rendering index of above 75. The presented devices are characterized by high luminous efficacies of above 30 lm/W on standard glass substrates without outcoupling enhancement.

Keywords

OLEDilluminationwhitestackedtriplet harvestingluminous efficacy
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1286: Symposium E – Molecular and Hybrid Materials for Electronics and Photonics , 2011 , mrsf10-1286-e01-01
Copyright
Copyright © Materials Research Society 2011

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References

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