Polymer electrophosphorescent light-emitting diode using aluminum bis(2-methyl-8-quinolinato) 4-phenylphenolate as an electron-transport layer

The characteristics of organic light-emitting diodes depend critically on the arrangement and choice of the constituent organic layers. Diodes constructed using poly(vinylcarbazole) doped with phosphorescent fac tris(2-phenylpyridine) iridium (III) [Ir(ppy)₃] as the polymer hole-transport layers and aluminum (III) bis(2-methyl-8-quinolinato) 4-phenylphenolate as hole-blocking and electron-transport layers were investigated. The peak efficiencies of the diodes were sensitive to the concentration of Ir(ppy)₃. With an optimal 2 wt% concentration, an effective external quantum efficiency of 10% photons/electron, a luminance power efficiency of 7.3 lm/W, and a low turn-on voltage of 6 V were obtained.