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

Abstract
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 , C 2 ′ )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.