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

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• High-quality hole injection layers (HILs) are critical for efficient and stable quantum dot light-emitting diodes (QLEDs).
• Nickel oxide (NiO_x) offers stability but suffers from limited hole injection efficiency compared to alternatives like poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS).

Purpose of the Study:

• To enhance the hole injection efficiency and operational stability of NiO_x-based HILs for QLEDs.
• To develop a practical method for improving NiO_x performance by addressing its inherent limitations.

Main Methods:

• Sol-gel synthesis of magnesium (Mg)-alloyed NiO_x nanoparticles.
• Ozone (O₃) treatment of Mg-alloyed NiO_x via atomic layer deposition to improve conductivity and reduce trap states.
• Fabrication and characterization of QLED devices utilizing the modified NiO_x HIL.

Main Results:

• Mg alloying deepened the work function of NiO_x (5.49 eV vs. 5.20 eV), and O₃ treatment boosted conductivity.
• QLEDs with the modified HIL achieved peak efficiencies of 17.85 cd A^-1 and 11.23 lm W^-1, a significant improvement over unmodified NiO_x.
• Operational stability dramatically increased, with a T₅₀ lifetime of 272 hours (at 1000 cd m^-2), more than doubling that of control devices.

Conclusions:

• The combination of Mg alloying and O₃ treatment is an effective strategy for developing high-performance NiO_x HILs.
• This approach offers a viable pathway for advancing the development of stable and highly efficient QLEDs.