Understanding the influence of doping in efficient phosphorescent organic light-emitting diodes with an organic p-i-n homojunction

Changhun Yun*, Guohua Xie, Caroline Murawski, Jonghee Lee, Fabian Ventsch, Karl Leo, Malte C. Gather

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

We report on the development and detailed investigation of highly efficient p-i-n phosphorescent organic light-emitting diodes (PhOLEDs) using 4,40-bis(carbazol-9-yl)-biphenyl (CBP) as a single organic semiconductor matrix. Following optimization of doping concentration of both the phosphorescent emitter molecule and of the p-and n-type dopants, an external quantum efficiency (EQE) of 15% and a power efficiency (PE) of 28 lm/W are realized at a luminance of 1000 cd/m(2). These values are comparable to the state-of-the-art for conventional complex multilayered PhOLEDs. By analyzing the device characteristics (i.e. electroluminescence spectra, the current density-voltage behavior of single carrier devices, the transient electroluminescent decay, and the impedance spectroscopy response), we find that the device performance is closely linked to the charge carrier balance in the device, which in turn is governed by the interplay of the conductivities of the doped layers and the transport of each charge carrier species within the emitting layer. (C) 2013 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)1695-1703
Number of pages9
JournalOrganic Electronics
Volume14
Issue number7
DOIs
Publication statusPublished - Jul 2013

Keywords

  • Organic light emitting diodes
  • Phosphorescence
  • p-i-n Photodiodes
  • Homojunction
  • TRIPLET-TRIPLET ANNIHILATION
  • CARRIER TRANSPORT
  • LAYER
  • DEVICES
  • ELECTROPHOSPHORESCENCE
  • SEMICONDUCTORS
  • OXIDE

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