Influences of evaporation temperature on electronic structures and electrical properties of molybdenum oxide in organic light emitting devices

The influence of evaporation temperatures on the electronic structures of molybdenum oxide ( MoO x ) films and the electrical properties of organic light emitting diodes were investigated. MoO x films evaporated at a high temperature and a high deposition rate are close to a stoichiometric phase, but become less effective when they are used as a hole injection layer. However, when MoO x is evaporated at a lower temperature and a slower rate, there are large amounts of defect-related states present in the forbidden gap, which make the films behave like a high work function conductor and an effective hole injection layer.