Search

The development of transition metal complexes for application in light-emitting devices is currently attracting significant research interest. Among phosphorescent emitters, those involving iridium (III) complexes have proven to be exceedingly useful due to their relatively short triplet lifetime and high phosphorescence quantum yields. The emission wavelength of iridium (III) complexes significantly depends on the ligands, and changing the electronic nature and the position of the ligand substituents can control the properties of the ligands. In this chapter, we discuss recent developments of phosphorescent transition metal complexes for organic light-emitting diode applications focusing solely on the development of iridium metal complexes. more...

The synthesis of a new series of neutral bis[2-(2′,4′-difluorophen-2′-yl)pyridine][1-(2′-aryl)-3-methylimidazol-2-ylidene]iridium(III) complexes is reported. Each complex has been characterized by NMR spectroscopy, UV/Vis spectrophotometry, and cyclic voltammetry, and the photophysical properties examined in depth. Furthermore, two of the complexes have been characterized by single-crystal X-ray diffraction analysis. By systematically modifying the cyclometalating aryl group on the N-heterocyclic carbene (NHC) ligand from 2,4-dimethoxyphenyl to 6-methoxy-2-methyl-3-pyridyl, the energy levels of the Ir complexes were modified to produce new blue emitters with increased HOMO and triplet-state energies. OLED devices fabricated with these emitters showed external quantum efficiencies (EQEs) in the range of 2.3-3.2 % with low turn-on values of 2.7-2.9 V and efficacies of up to 6.3 %. [ABSTRACT FROM AUTHOR] more...