Quantum Dot-Polymer Beads for Light Conversion Film Dispersion

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Solution Overview

Problem

Existing light conversion films face challenges in achieving uniform dispersion of quantum dots within matrix resins with low moisture- and vapor-permeability, leading to reduced light emitting efficiency and increased degradation at the edge portions, especially under high-temperature high-humidity environments.

Innovation Solution

A light conversion composite is developed using quantum dot-polymer beads prepared through a solvent volatilization method, which allows for uniform dispersion of quantum dots within a matrix resin with low permeability, preventing high-temperature degradation and enhancing light emitting efficiency by forming a polymer coating layer around the quantum dots to prevent aggregation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If quantum dots are dispersed into matrix resin with low moisture-permeability and vapor-permeability, then edge degradation is reduced, but quantum dot aggregation occurs and light emitting efficiency deteriorates

Engineering Contradiction:
Improveedge degradation resistanceVSAvoidlight emitting efficiency
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

A polymer coating layer is introduced as an intermediary between quantum dots and low-permeability matrix resin. This coating layer prevents quantum dot aggregation that would otherwise occur in low-permeability resins, while allowing the matrix resin to maintain its low moisture and vapor permeability for edge protection. The polymer coating acts as a mediator that resolves the conflict between dispersion stability and edge degradation resistance.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Stability of the object's composition

If quantum dots are dispersed into matrix resin with high moisture-permeability or vapor-permeability, then quantum dot dispersion is improved, but edge portion degradation increases

Engineering Contradiction:
Improvequantum dot dispersion uniformityVSAvoidedge degradation resistance
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The system employs local quality differentiation: the polymer coating layer provides a hydrophilic local environment that ensures uniform quantum dot dispersion, while the low-permeability matrix resin provides a protective bulk environment that prevents edge degradation. Each layer performs its specific function locally, resolving the contradiction between dispersion uniformity and edge protection.

Inventive Principle:
Principle #3Local quality

3Stability of the object's composition

If high temperature processing is used to mix quantum dots with low permeability matrix resin, then dispersion is achieved, but quantum dot degradation occurs

Engineering Contradiction:
Improvequantum dot dispersionVSAvoidquantum dot stability
Core Design Contradiction:
Stability of the object's compositionVSReliability

Solution Approach 1:

The polymer coating is applied to quantum dots in advance, before they are mixed with the low-permeability matrix resin. This preliminary coating action prevents aggregation and eliminates the need for high-temperature processing during subsequent mixing, thereby preserving quantum dot stability while achieving uniform dispersion in the matrix resin.

Inventive Principle:
Principle #10Preliminary action

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 achieves superior light emitting efficiency and significantly reduces edge degradation in light conversion films, maintaining performance under harsh environmental conditions without the need for high-temperature processing.

Implementation Method 1

forming a polymer coating layer around the quantum dots to prevent aggregation

Methodology Applied
Scientific EffectSteric stabilization:

Implementation Method 2

quantum dot-polymer beads prepared through a solvent volatilization method

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 3

a matrix resin having a low penetration ratio with respect to oxygen or moisture

Methodology Applied
Scientific EffectPermeation barrier: Permeation

Data Source

PatentEP3032923B1Method for preparing light conversion composite, light conversion film, backlight unit and display device having the same
Publication Date: 2019.12.04 LG ELECTRONICS INC
  • EP3032923B1 patent drawingFigure 1~3
  • EP3032923B1 patent drawingFigure 4
  • EP3032923B1 patent drawingFigure 5

AI summary

A light conversion composite including a matrix resin and quantum dot-polymer beads dispersed within the matrix resin. The light conversion composite has a wave number q of 0.0056 Å-1 to 0.045 Å-1 at a peak point in a scattering intensity graph according to wave numbers measured by using small angle X-ray scattering.