LAUSR

Abstract Homoleptic Ir(III) complexes, Ir(ppyTMS) 3 and Ir( m PppyTMS) 3 , based on 2-phenyl-5-(trimethylsilyl)pyridine (ppyTMS) and 2-(1,1′-biphenyl-3′-yl)-5-(trimethylsilyl)pyridine ( m PppyTMS) as cyclometalated ligands, respectively, were synthesized for highly efficient green phosphorescent organic light-emitting diodes (OLEDs). The trimethylsilyl and phenyl groups introduced on the 2-phenylpyridine ligand suppressed the intermolecular interactions and the triplet-triplet annihilation process taking place via molecular aggregation, which otherwise decrease the OLED efficiency. The green phosphorescent OLEDs doped with Ir(ppyTMS) 3 and Ir( m PppyTMS) 3 as green emitters exhibited maximum electroluminescent wavelengths of 525 and 529 nm, respectively, at an optimized doping concentration of 5%. The Commission Internationale de L'Eclairage coordinates of these OLEDs were (0.35,0.62) and (0.37,0.61), respectively, at a luminance of 1000 cd m −2 . The maximum external quantum efficiency and maximum power efficiency (PE max ) were 16.6%/66.1 lm W −1 for the Ir(ppyTMS) 3 device and 18.1%/70.3 lm W −1 for the Ir( m PppyTMS) 3 device, which were higher than those of Ir(ppy) 3 without substituents on the 2-phenylpyridine ligand. Moreover, the PE max value of the Ir( m PppyTMS) 3 device is one of the highest values among the reported devices fabricated using homoleptic Ir(III) complexes for green phosphorescent OLEDs.