Ultraviolet electroluminescence and blue-green phosphorescence using an organic diphosphine oxide charge transporting layer

We report electroluminescence at 338 nm from a simple bilayer organic light-emitting device (OLED) made using 4,4(')-bis(diphenylphosphine oxide) biphenyl (PO1). In an OLED geometry, the material is preferentially electron transporting. Doping the PO1 layer with iridium(III)bis(4,6-(di-fluorophenyl)-pyridinato-N,C2')picolinate (FIrpic) gives rise to electrophosphorescence with a peak external quantum efficiency of 7.8% at 0.09 mA/cm(2) and 5.9% at 13 mA/cm(2). The latter current density is obtained at 6.3 V applied forward bias.