Hole-blocking characteristics of 2,4,6-triphenyl-1,3,5-triazine as a non-transporting filler material

2,4,6-Triphenyl-1,3,5-triazine (TTA) has been used as a hole-blocking mater ial for electroluminescent devices (ELD) [R. Fink, C. Frenz, hi. Thelakkat, H.W. Schmidt, Macromolecules, 30, (1997) 8177]. The EL devices of the four layer structure, ITO/hole transporting layer(HTL)/emitting layer/Al, were fabricated. TTA was doped into the poly(n-vinylcarbazole) (PVK), which was spin-coated on indium tin oxide (ITO) film. The emitting layer, tris(8-hydr oxyquinolinato) aluminum(Alq(3)), was deposited on top of PVK film. The ELD emits characteristic green color generated from Alq(3) emitting layer. As the percentage of TTA was increased, the efficiency of devices increased. T he devices, which contained higher concentration of blocking material, were driven at a lower current under the same voltage. The optimum concentratio n of hole blocking material was 10 wt.%, which produced the highest ELD lum inescence. (C) 2000 Elsevier Science S.A. All rights reserved.