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 (Alq(3))-based organic light-emitting diodes show high brightness at very low operating voltage, 100 cd/m(2) at 3.2 V and 1000 cd/m(2) at 4.4 V, corresponding to a low turn-on voltage of 2.4 V. 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. (c) 2008 American Institute of Physics.