Self-Assembled Monolayer-Functionalized NiO Hole Injection layer for Improved Charge Injection in Quantum Dot...

Area of Science:

• Materials Science
• Organic Electronics
• Nanotechnology

Background:

• Quantum dot light-emitting diodes (QLEDs) are crucial for next-generation displays.
• Challenges in QLEDs include inefficient hole injection, charge imbalance, and unstable organic materials like PEDOT:PSS.
• Surface modification of hole injection layers is key to overcoming these limitations.

Purpose of the Study:

• To improve hole injection efficiency and charge balance in QLEDs.
• To explore the use of self-assembled monolayers (SAMs) for modifying inorganic hole injection layers.
• To enhance the overall performance and stability of QLED devices.

Main Methods:

• Fabrication of QLEDs with the structure ITO/HIL/TFB/QDs/ZnMgO/Al.
• Modification of the NiO hole injection layer (HIL) using Br-2PACz-based SAMs.
• Characterization of device performance, including turn-on voltage, external quantum efficiency (EQE), luminance, and current efficiency.

Main Results:

• QLEDs with (NiO+Br-2PACz) demonstrated a reduced turn-on voltage (2.4 V) and significantly enhanced EQE (8.30%) and luminance (88,831 cd/m²).
• Performance improvements include a 1.5 V reduction in turn-on voltage, a 1.99-fold increase in EQE, and a 3.63-fold increase in luminance compared to NiO-only QLEDs.
• The modified QLEDs outperformed PEDOT:PSS-based devices, attributed to reduced hole injection barrier, increased conductivity, and improved charge balance via SAMs.

Conclusions:

• Br-2PACz-based SAMs effectively passivate surface defects, improve hole injection, and reduce exciton quenching in NiO layers.
• The functionalization of inorganic hole injection layers with SAMs offers a simple yet effective strategy for enhancing QLED performance.
• This approach provides a viable alternative to unstable organic materials, paving the way for more efficient and stable QLED technology.