Reduced geminate recombination in iridium-based electrophosphorescent materials

Russell J Holmes, S. R. Forrest, T. Sajoto, A. Tamayo, P. I. Djurovich, M. E. Thompson

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


We demonstrate reduced geminate recombination of excitons in electrophosphorescent organic light emitting devices using the green phosphor fac-tris(1-(9′,9′-dimethyl-2′-fluorenyl)pyrazolato,N,C2)iridium(III). At low phosphor doping concentrations (<20 wt.%) in a N,N′-dicarbazolyl-3,5-benzene host, transient electroluminescence spectra show no bimolecular quenching at the highest excitation densities used. At higher doping concentrations (>60 wt.%), the transient decay reflects the presence of phosphor molecular aggregates. The roll-off in external quantum efficiency at high current densities is attributed to the field-assisted dissociation of charge pairs prior to exciton formation.

Original languageEnglish (US)
Pages (from-to)163-172
Number of pages10
JournalOrganic Electronics
Issue number3
StatePublished - Jun 2006
Externally publishedYes


  • Exciton quenching
  • Organic light emitting devices
  • Phosphorescence

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