Synthesis Of Cu-Modified Nickel Oxide Nanocrystals And Their Applications As Hole-Injection Layers For Quantum-Dot Light-Emitting Diodes

Solution-processed NiOx thin films have been applied as hole-injection layers (HILs) in quantum-dot light-emitting diodes (QLEDs). The commonly used NiOx HILs are prepared by the precursor-based route, which requires high annealing temperatures of over 275 degrees C to in situ convert the precursors into oxide films. Such high processing temperatures of NiOx HILs hinder their applications in flexible devices. Herein, we report a low-temperature approach based on Cu-modified NiOx (NiOx-Cu) nanocrystals to prepare HILs. A simple post-synthetic surface-modification step, which anchors the copper agents onto the surfaces of oxide nanocrystals, is developed to improve the electrical conductivity of the low-temperature-processed (135 degrees C) oxide-nanocrystal thin films. In consequence, QLEDs based on the NiOx-Cu HILs exhibit an external quantum efficiency of 17.5 % and a T-95 operational lifetime of similar to 2,800 h at an initial brightness of 1,000 cd m(-2), meeting the commercialization requirements for display applications. The results shed light on the potential of using NiOx-Cu HILs for realizing high-performance flexible QLEDs.