Efficient white-light-emitting diodes based on poly(N-vinylcarbazole) doped with blue fluorescent and orange phosphorescent materials

Abstract

We have fabricated polymer white-light-emitting devices possessing a single emitting layer containing a hole-transporting host polymer, poly(N-vinylcarbazole), and an electron-transporting auxiliary, 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole, doped with a blue-light-emitting amino-substituted distyrylarylene fluorescent dye and an orange-light-emitting osmium phosphor. The doubly doped device exhibited an intense white emission having Commission Internationale de l’Eclairage coordinates of (0.33, 0.34), a high external quantum efficiency of 6.12% (13.2cd∕A), and a maximum brightness of 11306cd∕m2. The color coordinates remained unchanged over a range of operating voltages, even at luminance as high as 1×104cd∕m2.