Enhancement of current injection in organic light emitting diodes with sputter treated molybdenum oxides as hole injection layers

摘要

The enhancement of current density and luminance in organic light emitting diodes is achieved by treating molybdenum oxide (MoO_3) hole-injection-layers with slight argon ion sputtering. The sputter treated MoO_3 layers provide improvement in current injection efficiency, resulting in better current density which is about ten times higher than that of the reference devices. Photoemission spectroscopy shows that molybdenum in MoO_3 is reduced to lower oxidation states after sputter treatment due to the removal of oxygen. As a result, gap states are formed to enhance metallic characteristics of the sputter treated MoO3 surface and facilitate better hole injection efficiency.