Ultrabright and stable top-emitting quantum-dot light-emitting diodes with negligible angular color shift

Area of Science:

• Materials Science
• Optoelectronics
• Display Technology

Background:

• Top-emitting quantum-dot light-emitting diodes (QLEDs) offer enhanced luminance and color purity for displays.
• However, top-emitting QLEDs face challenges including poor stability, low light outcoupling, and viewing-angle dependence, particularly for non-red emitters.
• The optimal device structure for non-red QLEDs is often incompatible with single-mode optical microcavities, hindering performance.

Purpose of the Study:

• To overcome the stability and performance limitations of top-emitting green QLEDs.
• To enable advanced device performance by addressing optical microcavity incompatibilities.
• To improve luminance, color purity, and operational lifetime in QLED displays.

Main Methods:

• Optimized determination of reflection penetration depths in QLED structures.
• Development of refractive-index-lowering processes for QLED fabrication.
• Narrowing the emission linewidth of quantum dots to reduce angular color shift.

Main Results:

• Achieved a peak luminance exceeding 1.6 million nits.
• Demonstrated a current efficiency of 204.2 cd/A.
• Obtained an operational lifetime (T95) of 15,600 hours at 1000 nits.
• Reached an external quantum efficiency of 29.2% without light extraction methods.
• Attained a minimal angular color shift (Δu'v' = 0.0052 from 0° to 60°).

Conclusions:

• The developed methods effectively overcome the limitations of green QLEDs, leading to significantly enhanced device performance.
• The optimized QLED structure achieves high luminance, efficiency, and stability without compromising light outcoupling.
• This advancement paves the way for high-performance, stable top-emitting QLED displays with excellent color fidelity across wide viewing angles.