Very low turn-on voltage and high brightness tris-(8-hydroxyquinoline) aluminum-based organic light-emitting diodes with a MoOx p-doping layer

We have demonstrated an organic light-emitting diode based on molybdenum oxide (MoOx) doped 4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine (m-MTDATA) as a p-type doping hole injection layer. The tris-(8-hydroxyquinoline) aluminum (Alq3)-based organic light-emitting diodes show high brightness at very low operating voltage, 100cd∕m2 at 3.2V and 1000cd∕m2 at 4.4V, corresponding to a low turn-on voltage of 2.4V. Such improved properties are attributed to the formation of the charge transfer complex produced by doping MoOx into m-MTDATA, which provides much more free hole carriers, and the introduction of an efficient electron-injecting layer to improve the performance.