Light Conversion Plate Protrusion Patterns for LED Efficiency

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Solution Overview

Problem

Current quantum dot-based light-emitting diode (LED) packages face issues with degradation due to heat and moisture, leading to non-uniform distribution and reduced luminous efficiency, as well as limited compatibility with sealing resins, which affects brightness and color reproducibility.

Innovation Solution

A light conversion plate with a quantum dot layer protected by an inorganic ligand layer and glass substrates, featuring protrusion patterns on the glass surfaces to enhance light extraction and prevent degradation, along with an air gap or low refractive index layer between the encapsulation layer and the light conversion plate to improve luminous efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If quantum dots are capped with hydrophobic ligand for dispersibility improvement, then dispersibility is improved, but compatibility with sealing resin deteriorates

Engineering Contradiction:
ImprovedispersibilityVSAvoidcompatibility with sealing resin
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

A silane coupling agent is introduced as an intermediary substance between the hydrophobic ligand-capped quantum dots and the hydrophilic sealing resin. The silane coupling agent contains both hydrophobic and hydrophilic functional groups, allowing it to bridge the interface between quantum dots and sealing resin, thereby improving compatibility and adhesion without compromising dispersibility

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent creates a composite structure where quantum dots, silane coupling agent, and sealing resin form a multi-component system. The silane coupling agent forms a transitional layer that combines properties of both hydrophobic and hydrophilic materials, enabling effective integration of quantum dots into the sealing resin matrix

Inventive Principle:
Principle #40Composite materials

2Illumination intensity

If quantum dots are used to improve brightness and color reproducibility, then luminous efficiency is improved, but degradation by heat and moisture worsens

Engineering Contradiction:
ImprovebrightnessVSAvoidresistance to heat and moisture
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent applies silane coupling agent treatment to quantum dots before encapsulation, creating a protective transitional layer that preemptively shields quantum dots from heat and moisture damage. This prior protection prevents degradation during operation while maintaining the quantum dots' optical performance

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The silane coupling agent serves as a protective intermediary between the quantum dots and the external environment (heat and moisture). This intermediary layer provides thermal and moisture barrier functions while maintaining the quantum dots' luminous properties

Inventive Principle:
Principle #24Intermediary (Mediator)

3Illumination intensity

If protrusion patterns are formed on glass substrate to enhance light extraction, then light extraction is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvelight extractionVSAvoidmanufacturing complexity
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent forms protrusion patterns with curved or spherical surfaces on the glass substrate. These curved structures enhance light extraction through increased scattering and reduced total internal reflection, while the standardized spherical geometry allows for relatively simple manufacturing processes such as laser writing or photoresist-based patterning

Inventive Principle:
Principle #14Spheroidality (Curvature)

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

The solution effectively prevents quantum dot degradation, enhances light extraction, and improves luminous efficiency by up to 8% through reduced reflection and increased light recycling, achieving high brightness and color reproducibility in LED packages.

Implementation Method 1

A light conversion plate with a quantum dot layer protected by an inorganic ligand layer and glass substrates

Methodology Applied
Scientific EffectPhysical barrier protection:

Implementation Method 2

featuring protrusion patterns on the glass surfaces to enhance light extraction and prevent degradation

Methodology Applied
Scientific EffectLight scattering: Scattering

Implementation Method 3

an air gap or low refractive index layer between the encapsulation layer and the light conversion plate to improve luminous efficiency

Methodology Applied
Scientific EffectRefraction: Refraction

Implementation Method 4

a light conversion plate with a quantum dot layer protected by an inorganic ligand layer

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 5

along with an air gap or low refractive index layer between the encapsulation layer and the light conversion plate to improve luminous efficiency

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP3088950B1Light-emitting diode package, backlight unit, and display device including a light conversion plate
Publication Date: 2021.02.24 LG ELECTRONICS INC
  • EP3088950B1 patent drawingFigure 1~3
  • EP3088950B1 patent drawingFigure 4~5(C)
  • EP3088950B1 patent drawingFigure 6~7

AI summary

A light conversion plate (10) including a first glass substrate (11); a light conversion layer (13) disposed on the first glass substrate (11) and including quantum dots (17) that convert incident light into light having a specific wavelength range; and a second glass substrate (15) disposed on the light conversion layer (13). Further, a surface of at least one of the first glass substrate (11) and the second glass substrate (15) includes protrusion patterns.