Highly efficient yellow-emitting iridium(III) complexes based on fluorinated 2-(biphenyl-4-yl)-2H-indazole ligands: Syntheses, structures, properties, and density functional theory calculations

Two new iridium (III) complexes (Ir1-Ir2) bearing different fluorinated 2-(biphenyl-4-yl)-2H-indazole-based compounds as cyclometalated ligands and Xantphos as an ancillary ligand were synthesized and fully characterized. The ultraviolet (UV)-vis absorption, photoluminescence, and electrochemistry properties were studied. The single crystal structures of Ir1-Ir2 were determined by X-ray diffraction, showing each adopts the distorted octahedral coordination geometry. To gain insights into the lowest energy electron transitions and the lowest triplet excited states, density functional theory calculations were used to further investigate the origination. Two complexes emit yellow photoluminescence with quantum yields of 49.7-72.5% in solution at room temperature. Their Commission Internationale de L'Eclairage color coordinates are (0.42, 0.53) and (0.39, 0.47), respectively.