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 Almq3 sublayer and region doped with an orange-red phosphorescent dopant, bis 2-phenyl-1-quinoline iridium acetylacetonate Ir pq 2acac . Electron-hole recombination in a thin spacing Almq3 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.
Anzenbacher, Pavel Jr.; Montes, Victor A.; and Takizawa, Shin-ya, "High-purity white light from a simple single dopant host-guest white organic lightemitting diode architecture" (2008). Chemistry Faculty Publications. 49.
Applied Physics Letters