Enhancing OLED electroluminescence by surface modification and work function adjustment of anode through NiO:Co coating

Abstract

This study presents an approach to improve the electroluminescence (EL) of organic light-emitting diodes (OLEDs) by coating an ultra-thin NiO:Co (NCO) layer on the anode. The NCO layer was pivotal in modifying anodic properties, including surface roughness, hydrophilicity, and work function, thereby promoting ohmic hole injection from the anode into the NPB layer and enhancing the current density and carrier recombination in OLEDs. Compared to OLEDs with a pristine ITO anode, the OLEDs with an NCO-coated ITO anode showed a significant enhancement in EL performance, including a 24.5 % increase in current density, an 84.9 % enhancement in brightness, and a 48.7 % boost in efficiency. Notably, coating NCO on the anode consistently enhanced hole injection regardless of whether ITO or PEDOT:PSS was used as the anode.