Cu-Doped nickel oxide prepared using a low-temperature combustion method as a hole-injection layer for high-performance OLEDs

Solution-processed Cu doped nickel oxide (Cu-NiO x ) is used as a hole injection layer (HIL) in phosphorescent green organic light-emitting diodes (OLEDs). Hole injection materials are very important for achieving high performance OLEDs. Herein, solution-processed Cu doped NiO x prepared using a combustion method is demonstrated as the HIL in OLEDs. Nickel oxide (NiO x ) thin films incorporated with p-type Cu dopants resulted in a significantly improved conductivity and hole-injection capability. The UV-ozone treated NiO x shows significantly better hole injection than that without being treated by UV-ozone. Our results show that phosphorescent green OLEDs with UV-ozone treated Cu:NiO x show a maximum current efficiency of 85.3 cd A −1 , which is remarkably higher than the conventional device based on poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS) which has a maximum current efficiency of 68.3 cd A −1 . Low-temperature combustion methods to deposit s-NiO x and s-Cu-NiO x on ITO glass to fabricate efficient green phosphorescent OLEDs.