| 초록 |
Three new Ir(III) compounds with deep blue phosphorescence have been synthesized. These molecules have the general formula of Ir(C∧N)2(L∧X) where CN = 2',6'-difluoro-2,3'-bipyridine (dfpypy), and L∧X = ancillary ligand such as 2-picolinate, pic (1), acetylacetonate, acac (2) or dipivaloylmethanoate, dpm (3). The ancillary ligands have been found to significantly destabilize both HOMO and LUMO level of the Ir(III) complexes, compared to Ir(dfpypy)3 without significantly changing the phosphorescence energy. Compounds 1 – 3 emit brightly blue phosphorescence with λmax = 440 – 460 nm and quantum efficiencies of 0.60 – 0.95 in solution and the solid state. Double-layer electroluminescent devices using compounds 1 – 3 as the dopant, CDBP as the host/hole tranporting layer, and TPBi as the electron transport layer have been fabricated. The EL device of compound 3 at the doping level of 20 wt% has the best performance with EQE of 10% – 15% at the brightness of 10 cd/m2 – 1000 cd/m2 and the maximum current efficiency of 22 cd/A. |
