Efficient Tandem Quantum-Dot LEDs Enabled by An Inorganic Semiconductor-Metal-Dielectric Interconnecting Layer Stack.

Area of Science:

• Materials Science
• Optoelectronics
• Nanotechnology

Background:

• Tandem configurations in light-emitting diodes (LEDs) are crucial for high-performance, multicolor devices.
• Previous tandem colloidal quantum dot LEDs (QLEDs) faced efficiency limitations due to unpassivated interfaces and solvent damage from interconnecting layers (ICLs).

Purpose of the Study:

• To develop and characterize a novel interconnecting layer (ICL) for tandem colloidal quantum dot LEDs (QLEDs).
• To address challenges of interface stability and solvent damage in QLED fabrication.
• To enhance charge balance and suppress current leakage in double-junction tandem QLEDs.

Main Methods:

• Fabrication of a novel ICL comprising a semiconductor-metal-dielectric stack.
• Experimental investigation of the ICL's role in charge balance, current leakage suppression, and solvent damage prevention.
• Performance evaluation of double-junction tandem QLEDs with the new ICL across various emission wavelengths.

Main Results:

• Achieved record external quantum efficiencies (EQEs) for double-junction tandem QLEDs: 40% for red, 49% for yellow, 50% for green, and 24% for blue.
• Demonstrated facile fabrication, material stability, and good optoelectronic coupling with the novel ICL.
• Confirmed the ICL's effectiveness in enabling charge balance and preventing solvent damage to underlying layers.

Conclusions:

• The developed semiconductor-metal-dielectric ICL significantly improves the performance of tandem QLEDs.
• This ICL strategy overcomes key limitations, paving the way for highly efficient, stable, and multicolor QLED devices.
• Record efficiencies achieved highlight the potential of this approach for advanced display and lighting applications.