High-purity white light from a simple single dopant host-guest white organic light-emitting diode architecture

White light with good color properties (color rendering index=82-87) is generated in a simple organic light-emitting diode comprising an emissive layer, composed of an undoped tris(4-methyl-8-quinolinato)aluminum (Almq(3)) sublayer and region doped with an orange-red phosphorescent dopant, bis(2-phenyl-1-quinoline)iridium acetylacetonate (Ir(pq)(2)acac). Electron-hole recombination in a thin spacing Almq(3) layer results in blue-green fluorescence, while the formed triplet excitons diffuse to the doped region and are harvested by the dopant to emit orange-red phosphorescence. The combination of blue-green and orange lights results in warm white light. This approach takes advantage of efficient migration of triplet excitons while being less demanding in terms of fabrication and color matching. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3005424].