At room temperature,two efficient red iridium(Ⅲ)complexes,(4tfmpq)2Ir(Pydtc)and(4tfmpq)2-Ir(Indtc),containing a unique four-membered ring Ir-S-C-S skeleton,have been successfully synthesized.These complexes use 4-(4-(trifluoromethyl)phenyl)quinazoline(4tfmpq)as the main ligand and dithiocarbamate deriva-tives(Na-Pydtc and Na-Indtc)as the ancillary ligands.The abundant nitrogen heterocycles in their molecular struc-ture enhance the electron mobility,while the different electron-donating units in the dithiocarbamate derivatives help to regulate photophysical properties.The complex(4tfmpq)2Ir(Pydtc)exhibited an emission peak at 611 nm and the quantum yield of 92.7%.The emission peak and quantum yield of complex(4tfmpq)2Ir(Indtc)were 614 nm and 90.9%,respectively.High-performance organic light-emitting diodes(OLEDs)using the double emissive layer structure were prepared by employing these two complexes as dopant.For device D1 using(4tfmpq)2Ir(Pydtc)as dopant,the maximum current efficiency(ηc,max)and maximum external quantum efficiency(EQEmax)reached 56.29 cd·A-1 and 32.53%,respectively,and the CIE(Commission Internationale de l'Eclairage)coordinates were(0.61,0.37).In addition,the device showed a lower efficiency roll-off at the brightness of 1 000 cd·m-2,with the EQE remaining at 28.44%.These results demonstrate the potential application of iridium(Ⅲ)complexes con-taining a four-membered ring Ir-S-C-S skeleton in OLEDs.