Synthesis and characterization of red iridium(III) complexes containing phenothiazine-phenylquinoline based on main ligand for solution-processed phosphorescent organic light-emitting diodes

A new series of red emitting phosphorescent Ir(III) complexes, [10-hexyl-2-(4-phenylquinolin-2-yl)-10H-phenothiazine]Iridium acetylacetonate [(PQHPT)2Ir(acac)], [10-hexyl-2-(4-phenylquinolin-2-yl)-10H-phenothiazine]Iridium picolinic acid [(PQHPT)2Ir(pic)] and [10-hexyl-2-(4-phenylquinolin-2-yl)-10H-phenothiazine]Iridium picolinic acid N-oxide [(PQHPT)2Ir(pic-N-O)] based on 10-hexyl-2-(4-phenylquinolin-2-yl)-10H-phenothiazine (PQHPT) main ligand and acetylacetonate (acac), picolinic acid (pic) and picolinic acid N-oxide (pic-N-O) ancillary ligands were synthesized for phosphorescent organic light-emitting diodes (PhOLEDs). The photophysical, electrochemical and electroluminescent (EL) properties of Ir(III) complexes were investigated. All of the Ir(III) complexes had high thermal stability and emitted deep-red light with an excellent color purity at CIE (Commission International de l’Eclairage) coordinates of (0.67, 0.30). The red emitting PhOLEDs based on ITO/PEDOT:PSS/TCTA:TPBI:TPD:Ir complex/cathode exhibit a maximum external quantum efficiency of 0.51% and luminance of 180 cd/m2, respectively.