Abstract
Efficient fluorescent white organic light-emitting diodes with low carrier-injection barriers were fabricated with device structure of indium tin oxide/N,N′-bis-(1-naphthy)-N,N′-diphenyl-1,1′-biphenyl-4-4′-diamine/white emission layer/1,3,5-tris(N-phenyl-benzimidazol-2-yl)benzene/lithium fluoride/aluminium. By blending in the blue host of 1-butyl-9,10-naphthalene-anthracene in the emissive layer an efficient electro-luminescent greenish-blue co-host of di(triphenyl-amine)-1,4-divinyl-naphthalene, with the doping of a trace amount of red dye of 4-(dicyano-methylene)-2-methyl-6-(julolidin-4-yl-vinyl)-4H-pyran, bright and colour-stable white emission with high power-efficiency of 14.6 lm/W at 100 cd/m 2 or current efficiency of 19.2 cd/A at 300 cd/m 2 or 18.7 cd/A at 10,000 cd/m 2 was obtained. The resulted synergistic increase in brightness and efficiency may be attributed to the presence of cascading new routes with comparatively lower electron injection barrier. © 2007.