Efficient red phosphorescent iridium complexes for organic light-emitting diodes based on 5-benzoyl-2-phenylpyridine ligands with fluorine and methyl moieties

Red phosphorescent emitters for OLEDs were synthesized using Ir(III) complexes based on 5-benzoyl-2-phenylpyridine ligands with fluorine and methyl substitution. Their electroluminescence, when doped in the emitting layers of multilayer OLEDs, was sensitive to their structural features. In particular, a highly efficient orange-red OLED showed a maximum luminance of 18,740 cd/m2 at 11 V, with a luminous efficiency of 25.9 cd/A, power efficiency of 8.74 lm/W, external quantum efficiency of 9.25% at 20 mA/cm2, and CIEx,y coordinates of (0.53, 0.47) at 8.0 V, respectively. A red OLED with CIEx,y coordinates of (0.66, 0.34) at 8.0 V exhibited a luminous efficiency, power efficiency and external quantum efficiency of 5.98 cd/A, 2.06 lm/W and 5.77% at 20 mA/cm2, respectively.

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► We develop Ir complexes with 5-benzoyl-2-phenylpyridine derivatives as ligands.
► We examine changes in fluorine and methyl groups in the phenyl moiety.
► These fluorine and methyl groups allow tuning of the band gap of Ir complexes, leading to improved color purity.