Synthesis And Study On Luminescent Properties Of New Phosphorescent Iridium Complexes With Functionalized Carbazole Group

Over three decades,development,organic light-emitting diode?OLED?technology has gradually perfected itself.Smart gadgets featuring OLED display have already made to market.In solid lighting sources,OLED lighting panels are in the dawn of mass production.OLED is still one of the hottest research areas in organic electronics at present.Phosphorescent materials play an important role in OLED,because they can utilize both singlet and triplet excitons,and reach a theoretical internal quantum efficiency of 100 %.Iridium???complexes are the most promising phosphorescent materials.Developing new ligands and modifying existing ligands can obtain different light-emitting complexes.On the base of orange parent?bt?₂Ir?acac?complex,novel flexible?cbbt?2Ir?acac?which carbazole was introduced into 2-phenylbenzo[d]thiazole via alkoxy chain was synthesized and characterized by IR and NMR.?cbbt?2Ir?acac?exhibited high luminescent efficiency?0.30?,short triplet lifetime?0.15 us?and high decomposition temperature?310??.?cbbt?2Ir?acac?showed the maximum emission at 560 nm,which was very similar to that of parent?bt?₂Ir?acac?.?cbbt?2Ir?acac?doped devices exhibited the maximum luminance of 17910 cd/m² and maximum current efficiency of25.5cd/A.More importantly,those device showed small efficiency roll-off of 30-35%at 10-100 mA/cm²,which was probably attributed to short lifetime of?cbbt?2Ir?acac?.Under the same device structure,external quantum efficiency?10.3%?of?cbbt?2Ir?acac?doped device outperformed those of the parent?bt?₂Ir?acac?doped devices.Moreover,three robust Ir???complexes which were based on the rigid ligand2-?4-?9H-carbazol-9-yl?phenyl?benzo[d]thiazole?cbt?system with three auxiliary ligand,namely?cbt?2Ir?acac?,?cbt?2Ir?tmd?and?cbt?2Ir?pic?,were synthesized and characterized by MS,IR and NMR.The effects of different auxiliary ligand on photophysical and electroluminescent properties were investigated.?cbt?2Ir?acac?doped device exhibited the best performances with the maximum current efficiency of44.2 cd/A?23.3 lm/W?,which were much better than those of parent?bt?₂Ir?acac?doped device?19.1 cd/A,9.3 lm/W?.Those results demonstrate that this type Ir???complexes are promising orange phosphorescent materials.