Quantum Dot Color Converter for WOLED Displays

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Solution Overview

Problem

Current color displays for large substrates face challenges in achieving improved color performance and high efficiency while maintaining a simple organic electroluminescent device structure, particularly in large-scale production, with existing methods like WOLEDs suffering from inferior color performance and reduced light efficiency.

Innovation Solution

The use of nanoparticles, specifically quantum dots and rods, in combination with a color filter to enhance light emission, where the nanoparticles convert light into longer wavelengths and the color filter improves color purity, integrated into a simple organic electroluminescent device structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If WOLED with color filter is used for large substrate processing, then productivity is improved, but color performance deteriorates

Engineering Contradiction:
ImproveproductivityVSAvoidcolor performance
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent uses quantum dots with specific size parameters (2-50 nm diameter) to control emission wavelength and spectral properties. By adjusting quantum dot size, the system achieves precise color control while maintaining high productivity in large substrate processing, resolving the contradiction between productivity and color performance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent combines quantum dots (semiconductor nanoparticles) with color filters in a composite structure. This composite approach allows the quantum dots to provide narrow bandwidth emission for superior color performance while the color filter enhances color purity, all within a WOLED architecture that maintains high productivity for large substrate processing.

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If color filters with narrow bandwidth are used to improve color performance, then color performance is improved, but light efficiency deteriorates

Engineering Contradiction:
Improvecolor performanceVSAvoidlight efficiency
Core Design Contradiction:
Manufacturing precisionVSLoss of energy

Solution Approach 1:

The patent employs quantum dots whose emission bandwidth is controlled by their size parameter (2-50 nm). This intrinsic narrow bandwidth emission provides superior color performance without the need for aggressive color filtering that would waste light, thus maintaining high light efficiency while achieving excellent color performance.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent utilizes the quantum confinement effect in quantum dots to achieve wavelength-specific emission through size control. Different sized quantum dots emit different wavelengths with narrow bandwidths, providing precise color control and high color performance while preserving light efficiency, as the emission is inherently selective rather than requiring broad filtering.

Inventive Principle:
Principle #32Color changes

3Manufacturing precision

If separate deposition of organic electroluminescent layers for each color is used, then color performance is improved, but manufacturing complexity increases

Engineering Contradiction:
Improvecolor performanceVSAvoidmanufacturing complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent uses a universal WOLED structure with quantum dots and color filters that can generate multiple colors (red, green, blue) from a single device architecture. This multi-functional approach eliminates the need for separate electroluminescent layers for each color, maintaining superior color performance while dramatically simplifying manufacturing processes for large substrates.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent introduces quantum dots as an intermediary between the white light source and the final color output. The quantum dots convert the broad spectrum white light into narrow bandwidth emissions at specific wavelengths, serving as a mediator that achieves precise color control without requiring complex separate layer deposition for each color.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Loss of energy

If tandem design with multiple emitting units is used, then light efficiency is improved, but device complexity increases

Engineering Contradiction:
Improvelight efficiencyVSAvoidstructure complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent achieves high light efficiency by optimizing the quantum dot size parameter (2-50 nm) to match the spectral requirements of the WOLED. This single-layer quantum dot approach with carefully controlled size parameters provides efficient wavelength conversion without requiring multiple stacked emitting units, thus maintaining high light efficiency while avoiding the structural complexity of tandem designs.

Inventive Principle:
Principle #35Parameter changes

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

This approach results in higher color purity, improved efficiency, reduced production costs, suitability for mass production, and extended device lifetimes, overcoming the limitations of prior art.

Implementation Method 1

The electronic element comprises a color converter layer comprising at least one light emitting semiconducting nanoparticle... the nanoparticles convert light into longer wavelengths

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

the color filter improves color purity

Methodology Applied
Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentEP3254313B1Electronic element and display
Publication Date: 2020.09.16 MERCK PATENT GMBH
  • EP3254313B1 patent drawingFigure 1a~2
  • EP3254313B1 patent drawingFigure 3~4
  • EP3254313B1 patent drawingFigure 5~6

AI summary

The present invention relates inter alia to a color display comprising nanoparticles and color filters.