Effects of Using a Ag Anode with a Co-evaporation Thin Film of MoOx and α-Naphthyl Diamine Derivative in Organic Light-Emitting Diode

We investigated the effects of using a Ag anode with the co-evaporation of molybdenum oxide (MoO x ) and N,N '-bis(1-naphthyl)-N,N '-diphenyl-1,1'-diphenyl-1,4'-diamine (α-NPD). The current density of the device with a Ag anode and a co-evaporation thin film was the highest among the various devices used owing to a low sheet resistance and charge transport. We discussed the mobility and carrier density of the co-evaporation thin film as compared with the electrical properties of the α-NPD thin film. The device with a Ag anode achieved high electroluminescence (EL) efficiency due to the optical design. In particular, the device with a Ag anode and a co-evaporation thin film showed an approximately 55% higher current efficiency than that with indium–tin oxide (ITO) and a MoO x layer.