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 IrIII-based triplet emitters using electron-withdrawing main-group moieties provides access to IrIIIphosphors 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-1and power efficiency of 5.0 Im W-1for the red OLED (X = B(Mes)2), 11.1 %, 35.0 cd A-1, and 26.8 Im W-1for the bluish-green device (X = OPh), 10.3%, 36.9 cd A-1, and 28.6 Im W-1for the bright green device (X = NPh2) as well as 10.7%, 35.1 cd A-1, and 23.1 Im W-1for the yellow-emitting device (X = SO2Ph) can be obtained. KGaA.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics