Enhanced hole injections in organic light-emitting devices by depositing nickel oxide on indium tin oxide anode

An ultrathin layer of nickel oxide (NiO) was deposited on the indium tin oxide (ITO) anode to enhance the hole injections in organic light-emitting diode (OLED) devices. A very low turn-on voltage (3 V) was actually observed for the device with NiO on ITO. The enhancement of hole injections by depositing NiO on the ITO anode was further verified by the hole-only devices. The excellent hole-injection ability of NiO was also demonstrated by devising a device with patterned NiO on the ITO anode. Our results suggest that the NiO/ITO anode is an excellent choice to enhance hole injections of OLED devices.