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A new iridium complex [(DfPPy)2Ir(PhCzKt)] was synthesized, its the cyclometalated ligand and auxiliary ligand are 2-(2,4-difluorophenyl)pyridine and 1-(4-(tert-butyl)phenyl)-3-(9-ethyl-9H- carbazol-3-yl)propane-1,3-dione, respectively. The thermally stability, UV–vis absorption, photoluminescence, quantum yield, phosphorescent lifetime, electrochemistry, and electroluminescent performances of (DfPPy)2Ir(PhCzKt) were investigated. This Ir complex shows a yellow emission in light-emitting device. We optimized device for many times, and finally achieved higher efficient light-emitting devices, the maximum external quantum efficiency of device reaches 7.58% without host's emission, and the efficiency roll-off is low at high luminance. The good performances of devices are related to this Ir(IIII) complex grafted by carbazolyl and tert-butyl. In addition, TCTA and Bepp2 in emitting layer acted as host materials play an important role for the improvement of devices' performances.
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