Enhanced electroluminescence efficiency of phosphorescent organic light-emitting diodes by controlling the triplet energy of the hole-blocking layer

Young Wook Park, Young Min Kim, Jin Hwan Choi, Tae Hyun Park, Jin Wook Jeong, Hyun Ju Choi, Byeong Kwon Ju

Research output: Contribution to journalArticle

4 Citations (Scopus)


This letter reports on the effect of the triplet energy (ET) of the hole-blocking layer (HBL) on triplet exciton quenching between the emissive layer (EML) host and the HBL of phosphorescent organic light-emitting diodes (PHOLEDs). Using different EML hosts and HBLs having different ET's and electron mobilities, the effects of the ET's of the HBL have been analyzed. When the ETof the HBL is lower than that of the EML host, the PHOLEDs show significant dependence of reduced device performances. PHOLEDs having a 3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole HBL show 65% improved external quantum efficiency (EQE) at 500 cd/m2with a 4, 4'4,-tris(N-carbazolyl)-triphenyl-amine host than that with an N,N-dicarbazolyl-4-4-biphenyl host, while PHOLEDs having a 2,9-dimethyl-4,7- diphenyl-1,10-phenanthroline HBL show 41% reduced EQE. To solve the remaining key issue of developing highly efficient PHOLEDs, the ETof matching the EML and the HBL is extremely desirable and is also explored.

Original languageEnglish
Article number5430929
Pages (from-to)452-454
Number of pages3
JournalIEEE Electron Device Letters
Issue number5
Publication statusPublished - 2010 May 1



  • Phosphorescent organic light-emitting diodes (PHOLEDs)
  • Triplet energy of hole-blocking layer (HBL)
  • Triplet quenching

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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