Synthesis, characterization, photophysical and electrochemical properties of new phosphorescent dopants for OLEDs

New heteroleptic iridium(Ill) complexes of 2-(p-substituted-phenyl)-pyridine were synthesized and characterized. These complexes have two cyclometalated ligands (CN) and a bidentate ancillary ligand (LX), that is, (CN)(2)Ir(LX). LX was either acetylacetonate or 5-nitro-8-hydroxy quinolate. Substitution on the p-phenyl of CN ligands was used to alter the electronic properties of these complexes. The (CN)(2)Ir(acac) complexes show phosphorescence with good quantum yields and microsecond lifetimes and also show photoluminescence over a wide visible range (lambda(max) = 503-620 nm). The HOMO level and triplet energy level of these complexes were also determined. These data indicate their potential use as emitting materials for organic light emitting diodes, OLEDs. (c) 2008 Elsevier Ltd. All rights reserved.