Tris-heteroleptic cyclometalated iridium(III) complexes with ambipolar or electron injection/transport features for highly efficient electrophosphorescent devices

KGaA, Weinheim. A series of tris-heteroleptic phosphorescent cyclometalated IrIII complexes with two different cyclometalating ligands and one ancillary ligand was synthesized. Through manipulation of the electronic features of individual cyclometalating ligands, not only the emission color and electrochemical properties of these IrIII complexes can be tuned, but also unique charge carrier injection and transport traits can be conferred to them. Owing to the enhanced electron injection/transport and ambipolar characters associated with these tris-heteroleptic structures, these IrIII emitters showed very impressive electroluminescent performance with a maximum external quantum efficiency of 20.20 %, luminance efficiency of 69.41 cdA-1 and power efficiency of 35.15 Lm W-1. These results provide a new outlet to design and synthesize highly efficient electrophosphors for phosphorescent organic light-emitting diodes.