Quantum Light Emitting Diode Prism Light Extraction

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Solution Overview

Problem

Quantum light emitting diodes (QLEDs) face reduced brightness due to light loss from quantum particles emitting light from side surfaces, leading to decreased out-coupling efficiency and shorter lifetimes from thermal degradation.

Innovation Solution

Incorporating a light-amount enhancing layer with prism patterns that guide emitted light towards the emitting side, where quantum particles are positioned between adjacent prisms, enhancing light directionality and reducing losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If quantum particles are used in the emitting layer, then thermal stability and oxidation resistance are improved, but light loss from side surface emission reduces brightness

Engineering Contradiction:
Improvethermal stabilityVSAvoidbrightness
Core Design Contradiction:
ReliabilityVSIllumination intensity

Solution Approach 1:

The patent converts the harmful side surface light emission into a beneficial effect by introducing a photonic crystal structure that transforms the lateral light into useful upward-directed light, thereby improving brightness while maintaining the thermal stability benefits of quantum particles

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent introduces a new dimensional aspect by adding a photonic crystal layer with periodic structure that manipulates light propagation in three dimensions, redirecting light that would otherwise be lost sideways into the upward emission direction

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If quantum particles emit light from side surfaces, then light emission occurs in multiple directions, but out-coupling efficiency decreases

Engineering Contradiction:
Improvelight emission directionsVSAvoidout-coupling efficiency
Core Design Contradiction:
Adaptability or versatilityVSProductivity

Solution Approach 1:

The photonic crystal structure converts the multi-directional light emission (which causes light loss) into a beneficial effect by selectively enhancing the upward-directed light components while suppressing lateral emission, thereby improving out-coupling efficiency

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Illumination intensity

If current density is increased to improve brightness, then brightness increases, but thermal degradation accelerates and lifetime reduces

Engineering Contradiction:
ImprovebrightnessVSAvoidlifetime
Core Design Contradiction:
Illumination intensityVSDuration of action of stationary object

Solution Approach 1:

The photonic crystal structure allows the device to achieve higher brightness with lower current density by improving light extraction efficiency, thereby reducing thermal load and extending device lifetime while maintaining high brightness output

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Improves brightness and out-coupling efficiency by redirecting lateral light emissions towards the display side, thereby increasing the quantum light emitting diode's brightness and extending its operational lifespan.

Implementation Method 1

a light-amount enhancing layer having a structure configured to guide emitted light toward an emitting side

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP3336914B1Quantum light emitting diode and quantum light emitting device including the same
Publication Date: 2020.11.04 LG DISPLAY CO LTD
  • EP3336914B1 patent drawingFigure 1~2B
  • EP3336914B1 patent drawingFigure 3A~3B
  • EP3336914B1 patent drawingFigure 4~5

AI summary

A quantum light emitting diode (100) comprises a first electrode (110); a second electrode (120) facing the first electrode (110); a light-amount enhancing layer (170) between the first and second electrodes and having a structure guiding emitted light toward an emitting side; and an emitting material layer (150) between the light-amount enhancing layer (170) and the second electrode (120) and including a quantum particle (152) at the structure of the light-amount enhancing layer (170).