Suppression of roll-off characteristics of electroluminescence at high current densities in organic light emitting diodes by introducing reduced carrier injection barriers

Yousuke Setoguchi, Chihaya Adachi

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37 Citations (Scopus)

Abstract

We experimentally investigated suppression of the roll-off characteristics of the electroluminescence efficiency at high current densities in organic light emitting diodes (OLEDs). To increase exciton density, we propose a nonheterostructure OLED that consists of a single emitting layer of 4, 4′ -bis[(N-carbazole)styryl]biphenyl (BSB-Cz) and layers locally with doped donors/acceptors on the cathode and anode sides. The OLED exhibited suppression of the roll-off characteristics at high current densities over 100 A/ cm 2 with balanced bipolar injection and transport, resulting in the high exciton density of 1024 cm-3 s-1. Furthermore, amplified spontaneous emission with a relatively low threshold of Eth =24 μJ/ cm2 was obtained by optically pumping the single-layer device. However, to realize electrical excitation it was necessary to reduce the lasing threshold by two orders of magnitude or to inject a 100 times higher current density.

Original languageEnglish
Article number064516
JournalJournal of Applied Physics
Volume108
Issue number6
DOIs
Publication statusPublished - Sep 15 2010

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carrier injection
electroluminescence
high current
light emitting diodes
retarding
current density
excitons
thresholds
carbazoles
spontaneous emission
lasing
pumping
anodes
cathodes
injection
excitation

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

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abstract = "We experimentally investigated suppression of the roll-off characteristics of the electroluminescence efficiency at high current densities in organic light emitting diodes (OLEDs). To increase exciton density, we propose a nonheterostructure OLED that consists of a single emitting layer of 4, 4′ -bis[(N-carbazole)styryl]biphenyl (BSB-Cz) and layers locally with doped donors/acceptors on the cathode and anode sides. The OLED exhibited suppression of the roll-off characteristics at high current densities over 100 A/ cm 2 with balanced bipolar injection and transport, resulting in the high exciton density of 1024 cm-3 s-1. Furthermore, amplified spontaneous emission with a relatively low threshold of Eth =24 μJ/ cm2 was obtained by optically pumping the single-layer device. However, to realize electrical excitation it was necessary to reduce the lasing threshold by two orders of magnitude or to inject a 100 times higher current density.",
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