Synthesis, characterization of the phenylquinoline-based on iridium(Ⅲ) complexes for solution processable phosphorescent organic light-emitting diodes

摘要

A new series of highly efficient Ir(Ⅲ) complexes, (DPQ)_2Ir(pic-N-O), (F_4PPO)_2Ir(pic-N-O), (F_4PPO)_2Ir(pic-N-O), and (CPQ)_2lr(pic-N-O) were synthesized for phosphorescent organic light-emitting diodes (PhOLEDs), and their photophysical, electrochemical, and electroluminescent (EL) properties were investigated. The Ir(Ⅲ) complexes, including picolinic acid N-oxide (pic-N-O) ancillary ligand, are comprised with the various main ligands such as 2,4-diphenylquinoline (DPQ), 4-phenyl-2-(2,3,4,5-tetrafluorophenyl)quinoline (F_4PPO), 2-(9,9-diethyl-9H-fluoren-2-yl)-4-phenylquinoline (FPQ) and 9-ethyl-3-(4-phenylquino-lin-2-yl)-9H-carbazole. Remarkably, high performance PhOLEDs using a solution-process-able (DPO)_2Ir(pic-N-O) doped CBP host emission layer were fabricated to give a high luminance efficiency (LE) of 26.9 cd/A, equivalent to an external quantum efficiency (EQE)of 14.2%. The calculated HOMO-LUMO energy gaps for (DPO)_2lr(pic-N-O), (F_4PPQ)_2Ir(pic-N-O), (FPQ)_2Ir(pic-N-O) and (CPO)_2Ir(pic-N-O) were in good agreement with the experimental results.