Highly Efficient Organic Light Emitting Diodes with Hole Injection Layer of Thermally Evaporated Molybdenum Oxide

Abstract

Thermally evaporated MoO3 film was deposited to coated indium tin oxide (ITO) anode in organic light-emitting diodes (OLEDs) and its effect on the improvement of electroluminescence were studied. O-2 plasma treated ITO (O-2-ITO) and MoO3-coated ITO were ex-situ investigated using synchrotron radiation photoemission spectroscopy. The work function of MoO3-coated ITO was higher by 0.35 eV than that of O-2-ITO. Thus, the hole injection barrier at the interface could be reduced by the deposition Of MoO3, resulting in reduction of operation voltage from 16.5 to 14.6 V at 100 mA/cm(2) and enhancement of the electroluminescence property of OLEDs.