Efficient electroluminescent tertiary europium(III) β-diketonate complex with functional 2,2′-bipyridine ligand

A new red electroluminescent complex (2Fphen-bpy)Eu(DBM)(3)(2Fphen-bpy: 4-(2,4-difluorophenylene)-2,2'-bipyridine; DBM: dibenzoylmethanate) was designed and synthesized. X-ray single crystal structural analysis shows that the dihedral angles involving the difluorophenylene moiety and two pyridine rings of the 2,2'-bipyridine unit in (2Fphen-bpy)Eu(DBM)(3) are 42 degrees and 51.6 degrees, indicant of non-conjugation between the two segments. The europium complex was incorporated into the doped electroluminescent device: ITO/TPD(40 nm)/(2Fphenbpy)Eu(DBM)(3):CBP(30nm, 3%)/BCP(20nm)/Alq(3)(30nm)/LiF(1nm)/Al(100nm). At the brightness of 100cd/m(2), the current and power efficiency are about 2.53 cd/A and 0.791m/W, respectively. In comparison with the inefficient control device using (2,2'-bipyridine)Eu(DBM)(3) as the red emitter in the same configuration, the introduction of difluorophenylene moiety into the Eu(Ill) complex could possibly account for the improved performance of the title compound. (c) 2007 Published by Elsevier B.V.