Efficient yellow OLEDs based on bis-tridentate iridium(III) complexes with two C boolean AND N boolean AND N-coordinating ligands

摘要

Four bis-tridentate iridium(III) complexes with two different C boolean AND N boolean AND N-coordinating ligands have been synthesized and characterized. All complexes exhibited yellow/orange emission peaking at 580-604 nm with short lifetimes of 1.4-1.6 mu s and medium photoluminescence quantum yields (PLQYs) of 31%-53%. These complexes exhibit good thermal stability with decomposition temperature (T-d) exceeding 310 degrees C. The luminescence efficiency and thermal stability of iridium complexes were improved by the m-substituted CF3 groups. As a result, complex 2 exhibited the highest PLQYs of 0.53 and T-d of 348 degrees C. The OLEDs based on complex 2 showed good performances. The device at 2% doping concentration showed a maximum current efficiency of 36.4 cd A(-1), power efficiency of 29.1 lm W-1 and external quantum efficiency (EQE) of 14.4%. These results suggest that these complexes have potential for the application in high-efficiency OLEDs.