Synthesis of New Europium Complexes and Their Application in Electroluminescent Devices

摘要

Several substituted phenanthrolines (L=pyrazino 2, 3-f 1,10 phenanthroline (PyPhen), 2-methylpyrazino 2,3-f 1,10 phenanthroline (MPP), dipyrido 2,3-a:2',3'-c phenazine (DPPz), 11-methyldipyrido 3,2-a:2',3'-c phenazine (MDPz), 11, 13-dimethyldipyrido 3,2-a:2',3'-c phenazine (DDPz), and benzo i dipyrido 3,2-a:2',3'-c phenazine (BDPz) were successfully prepared and (TTA) and L in good yields. Irradiation at the absorption band between 320-390 nm of all these europium complexes, except Eu-BDPz, in solution or in the solid state leads to the emission of a sharp red band at ～612 nm, a characteristic Eu~(3+) due to the transition ~5D_0→~7F_2. No emission from the ligands was found. The result indicates that complete energy transfer Eu-BDPz exhibites a strong emission at around 550 nm from the coordinated BDPz ligand and a weak emission at 612 nm from the central europium ion. Incomplete energy transfer from the ligand to the central Eu~(3+) ion was observed for the first time. Several electroluminescent devices (A-I) using Eu-PyPhen, Eu-MPP, Eu-DPPz, and Eu-DDPz as dopant emitters with the device configuration: TPD or NPB (50 nm)/Eu:CBP (1.7-7, 30 nm)/BCP (20-30 nm)/Alq (25-35 nm) (where TPD: 4,4'-bis N-(p-tolly)-N-phenylamino biphenyl; NPB: 4, 5'-bis 1-naphthylphenylaminobiphenyl; CBP: 4,4'-N, N'-dicarbazole biphenyl; BCP: 2, 9-dimethyl-4, 7-diphenyl-1, 10-phenanthroline; Alq: tris 8-hydroxyquinoline aluminum) were fabricated. Some of these devices emit saturated red light and are the only europium complex-based devices that show a brightness of more than 1000 cdm~(-2).