Mg-Incorporated Nickel Oxide Hole Injection Layer for Stable and Efficient Quantum Dot Light-Emitting Diodes

High-quality hole injection layers (HILs) are essential for efficient and stable quantum dot light-emitting diodes (QLEDs). While NiOx is a stable alternative to the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) HIL, its low hole injection limits its practical application. This work enhances NiOx hole injection efficiency by combining Mg alloying to deepen work function (5.49 eV vs 5.20 eV) with O3 treatment to boost conductivity while suppressing traps. Using sol–gel synthesized Mg-alloyed NiOx nanoparticles followed by O3 treatment via atomic layer deposition, the resulting QLEDs achieve peak efficiencies of 17.85 cd A–1 and 11.23 lm W–1, representing 54% and 171% improvements over NiOx-based QLEDs (11.56 cd A–1, 4.15 lm W–1). Operational stability significantly improves, with a T50 lifetime of 272 h (L0 = 1000 cd m–2), over 2.2-fold that of NiOx-based QLEDs (84 h). This methodology provides a viable pathway to develop a NiOx HIL for advancing stable and high-efficiency QLEDs.