Novel polypyridyl ruthenium(II) complexes for electroluminescence

Several kinds of polypyridyl ruthenium complexes, [Ru(L)(2)(L)](PF6)(2) (L, L' = PBIm-H, bpy, dmbpy, o-phen) were synthesized and applied to single-layered LECs as emitting materials to invent new light-emitting electrochemical cells (LECs) and study the effect of the ligands of Ru (II) complexes on properties of LECs. Emission colors ranging from orange-red to red were obtained by tuning the molecular structure. The current efficiency of newly prepared samples was better than that of known samples [Ru(bPY)(3)](PF6)(2). The device of [Ru(bPY)(2)(dmbpy)](PF6)(2) showed the brightest and most efficient characteristics on the LEC. It operated with a current efficiency of 1.0 cd/A. That efficiency was better than that of the known sample of [Ru(bpy)(2)L](2+) (L = 2,2'-bipyridine-4,4'-dimethanol), which showed an efficiency of 0.6 cd/A. (C) 2004 Elsevier B.V. All rights reserved.