New trifluoromethyl modified iridium(III) complex for high-efficiency sky-blue phosphorescent organic light-emitting diode

A new and efficient trifluoromethyl modified sky-blue iridium(III) coordination compound (Ir-CF₃) is well designed and prepared by using bis(trifluoromethyl) modified 4-methyl-2-phenylpyridine as the cyclometalating ligand and 2-(1H-imidazol-2-yl)pyridine as the auxiliary ligand. Ir-CF₃ shows intensive sky-blue phosphorescence (465 nm with 494 nm as shoulder), high solution photoluminescence efficiency (0.22). The incorporation of trifluoromethyl moiety into the complex not only enhances the robust chemical stability but also provides the steric hindrance beneficial to organic light-emitting diodes. The sky-blue OLEDs based on this complex show narrow emission band with full width at half maxima of 54 nm. The peak power efficiency, current efficiency and external quantum efficiency of electroluminescence are as high as 36.05 lm/W, 51.45 cd/A and 21.74%, respectively.