Phosphorescence quantum efficiency and intermolecular interaction of iridium(III) complexes in co-deposited films with organic semiconducting hosts

Yuichiro Kawamura, Kenichi Goushi, Jason Brooks, Julie J. Brown, Hiroyuki Sasabe, Chihaya Adachi

Research output: Contribution to journalConference article

Abstract

We accurately measured the absolute photoluminescence (PL) quantum efficiency (ηPL) of organic solid-state thin films by using an integrating sphere. We measured the ηPL of conventional organic materials used in organic light emitting diodes, such as a tris (8-quinolionolato)aluminum(III) complex (Alq3), and a phosphorescent 1.5mol%-fac-tris(2-phenylpyridyl)iridium(III):4,4'-bis(carbazol-9-yl)-2, 2'-biphenyl [Ir(ppy)3:CBP] co-deposited film. Alq3 and Ir(ppy)3:CBP showed a ηPL = 20±1% and 97 ± 2%, which corresponded well to external electroluminescence efficiency using these materials. We also measured red emitting bis[2-(2'-benzothienyl) pyridinato-N,C3] (acetylacetonato) iridium(III) [Btp 2Ir(acac)] with CBP, and the blue complex, bis[(4,6-difluorophenyl) pyridinato -N,C2](picolinato)iridium(III) [FIrpic], with m-bis(N-carbazolyl)benzene. The maximum ηPL values for Btp 2Ir(acac), and FIrpic were 51±1% (at 1.4mol%), and 99±1% (1.2mol%), respectively. These results suggest that the ηEL of red phosphorescent OLEDs using Btp2Ir(acac) as the dopant can be as high as 10%, and blue devices using FIrpic can reach the theoretical limit of 20%.

Original languageEnglish
Article numberDD4.5
Pages (from-to)73-78
Number of pages6
JournalMaterials Research Society Symposium Proceedings
Volume846
Publication statusPublished - Aug 25 2005
Externally publishedYes
Event2004 MRS Fall Meeting - Boston, MA, United States
Duration: Nov 29 2004Dec 1 2004

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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