Improvement of luminescence efficiency by electrical annealing in single-layer organic light-emitting diodes based on a conjugated dendrimer

M Dongge, JM Lupton, R Beavington, PL Burn, Ifor David William Samuel

Research output: Contribution to journalArticlepeer-review

Abstract

In this paper, we study the effects of electrical annealing at different voltages on the performance of organic light-emitting diodes. The light-emitting diodes studied here are single-layer devices based on a conjugated dendrimer doped with 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole as the emissive layer. We find that these devices can be annealed electrically by applying a voltage. This process reduces the turn-on voltage and enhances the brightness and efficiency. We obtained an external electroluminescence quantum efficiency of 0.07% photon/electron and a brightness of 2900 cd m(-2) after 12.4 V electrical annealing, which are about 6 times and 9 times higher than un-annealing devices, respectively. The improved luminance and efficiency are attributed to the presence of a space charge field near the electrodes caused by charging of traps.

Original languageEnglish
Pages (from-to)520
Number of pages520
JournalJournal of Physics D : Applied Physics
Volume35
Publication statusPublished - 21 Mar 2002

Keywords

  • ELECTROLUMINESCENT DEVICES
  • POLYMER MORPHOLOGY
  • FILM MORPHOLOGY
  • PERFORMANCE
  • STABILITY

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