Patent ID: 7320834

Claim:
An organic light emitting diode (OLED) comprising: an anode on a substrate, an electroluminescent medium on said anode, and a cathode on said electroluminescent medium, characterized in that said electroluminescent medium comprises a light emitting layer comprising a phosphorescent Ir complex having the following structures (I) or (II): wherein X is an arbitrary monoanionic bidentate ligand; Z is an arbitrary atomic moiety capable of forming a nitrogen-containing heterocyclic group; R 1 is selected from the group consisting of H, halogen, C1-C6 alkyl, halogen-substituted C1-C6 alkyl, C1-C6 alkoxy, phenyl C1-C6 alkyl, amino, and aryl; m is 0 or any positive integer determined by the ring size of said nitrogen-containing heterocyclic group; R 2 is selected from the group consisting of H, halogen, C1-C6alkyl, halogen-substituted C1-C6alkyl, C1-C6alkoxy, phenyl C1-C6alkyl, amino, aryl, and heterocyclic aryl; and R 3 is aryl or heterocyclic aryl; and provided that said nitrogen-containing heterocyclic group containing said Z moiety is not pyridine, quinoline or isoquinoline.