High-efficiency long-lifetime phosphorescent OLED devices based on electron-trapping iridium (III) complexes

We have developed new iridium (III) complexes having coumarin, including its aza-analogue structure, in their ligands. These Ir complexes are highly emissive with colors ranging from yellow, yellowwish-green to green. Electrochemical analysis shows that the reduction and oxidation potentials of these complexes occur at significantly less negative and more positive potentials, respectively, than are found for typical Ir(III) complexes in OLEDs, indicating these complexes are electron trapping instead of hole trapping. Long-lived phosphorescent OLEDs fabricated with these new Ir complexes give external quantum and power efficiencies above 18% and 33 lm/W, respectively.