Anthraquinonyl isoquinoline-based deep-red emissive neutral iridium(III) complexes for solution‐processed organic light‐emitting diodes

Three high-efficiency deep-red neutral iridium(III) complexes are rationally designed and prepared using a mild method by introducing condensed ring (anthraquinonyl isoquinoline) as the cyclometalated ligand. The frequently-used ancillary ligands (acetylacetone, hexafluoroacetylacetone, picolinic acid) help to regulate the photophysical properties of the three iridium(III) complexes. In both solution and aggregated states, these three iridium(III) phosphors presented the intense deep-red phosphorescence, with the peak wavelength at 676, 634, and 648 nm, respectively. Additionally, Ir-acac, Ir-CF3 and Ir-pic exhibited high photoluminescence quantum yields (PLQYs) of 20 %, 18 %, and 17 % in dichloromethane, respectively. Furthermore, the efficient solution-processed electroluminescent devices were demonstrated with these emitters. The maximum external quantum efficiencies for the devices reached 5.94 % (Ir-acac), 0.55 % (Ir-CF3), and 3.16 % (Ir-pic), featuring the electroluminescent spectral peaks at 654, 632, 644 nm, respectively.