Manipulating charge-transfer character with electron-withdrawing main-group moieties for the color tuning of iridium electrophosphors

Guijiang Zhou, Cheuk Lam HO, Wai Yeung WONG*, Qi Wang, Dongge Ma, Lixiang Wang, Zhenyang Lin, Todd B. Marder, Andrew Beeby

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

446 Citations (Scopus)

Abstract

A new and synthetically versatile strategy has been developed for the phosphorescence color tuning of cyclometalated iridium phosphors by simple tailoring of the phenyl ring of ppy (Hppy = 2-phenylpyridine) with various main-group moieties in [Ir(ppy-X)2(acac)] (X = B(Mes)2, SiPh3, GePh3, NPh2, POPh2, OPh, SPh, SO2Ph). This can be achieved by shifting the charge-transfer character from the pyridyl groups in some traditional iridium ppy-type complexes to the electron-withdrawing main-group moieties and these assignments were supported by theoretical calculations. This new color tuning strategy in Ir III-based triplet emitters using electron-withdrawing main-group moieties provides access to IrIII phosphors with improved electron injection/electron transporting features essential for highly efficient, color-switchable organic light-emitting diodes (OLEDs). The present work furnished OLED colors spanning from bluish-green to red (505-609 nm) with high electroluminescence efficiencies which have great potential for application in multicolor displays. The maximum external quantum efficiency of 9.4%, luminance efficiency of 10.3 cd A-1 and power efficiency of 5.0 Im W -1 for the red OLED (X = B(Mes)2), 11.1 %, 35.0 cd A -1, and 26.8 Im W-1 for the bluish-green device (X = OPh), 10.3%, 36.9 cd A-1, and 28.6 Im W-1 for the bright green device (X = NPh2) as well as 10.7%, 35.1 cd A-1, and 23.1 Im W-1 for the yellow-emitting device (X = SO2Ph) can be obtained.

Original languageEnglish
Pages (from-to)499-511
Number of pages13
JournalAdvanced Functional Materials
Volume18
Issue number3
DOIs
Publication statusPublished - 11 Feb 2008

Scopus Subject Areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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