Highly efficient orange and white electrophosphorescence from solution-processible iridium(III) complexes

Abstract

The luminescent properties of two cyclometalated iridium complexes containing 2-phenylbenzothiazole ligand were investigated. With diphenylamino groups in the ligands, these iridium complexes can form neat films by spin coating their solutions. It is also possible to prepare their doped films in small molecular host matrix N,N ′-dicarbazolyl-4,4′-biphenyl by spin coating. Partially solution-processed organic light-emitting diodes (OLEDs) were fabricated with a luminance efficiency of 20.18 cd A −1 (7.81%), which is even higher than the vacuum-deposited device data for these two complexes, and also better than those for other solution-processed iridium dopant/small molecular host systems. The two-element white OLEDs containing these orange phosphors and traditional blue-emitting iridium in N,N ′-dicarbazolyl-4,4′-biphenyl host also exhibited high efficiency of 12.39 cd A −1 . It is suggested that the incorporation of the diphenylamino substituents and thus the good hole-injecting and solution processing ability of these iridium complexes are responsible for the good performance. Two iridium complexes decorated by diphenylamino substituents in cyclometalating ligands are suitable for solution processing to fabricate monochromic and white organic light-emitting diodes, which exhibit even better performance than their vacuum-deposited devices or other solution-processed iridium phosphors/small molecular host systems. • The electrophosphorescence of two iridium complexes containing 2-phenylbenzothiazole ligands are studied. • The incorporation of arylamino groups in ligands makes these complexes solution-processible. • High-performance orange and white organic light-emitting diodes were realized with these iridium complexes as doped emitters.