Blue Electroluminescent Devices Using the Dye Doped Polymers asEmitter and the Organic Molecule Film as Hole Blocking Layer

By placing a hole blocking layer between the polymer and the metallic electrode, we have achieved improved efficiencies for blue electroluminescent devices fabricated with poly (N-vinylcarbazole) doped with 1, 1, 4, 4, -tetraphenyl-1, 3-butadiene as the emitter layer and with aluminum and indium/tin-oxide as the electron and hole injecting electrodes. This bilayer device yields bright blue emission having intensity of 300cd/m², in same case the devices without hole blocking layer have luminance of only 44 cd/m².