Luminous Body Ligand Design for OLED Light Efficiency

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Solution Overview

Problem

White OLED display devices suffer from reduced light efficiency due to significant absorption of white light by color filter layers, leading to inefficient emission of red, green, and blue colors in pixel regions.

Innovation Solution

A luminous body with a first moiety of inorganic emitting particles and a second moiety of silsesquioxanes, where one ligand is polar and the other is non-polar, is used to enhance dispersion properties in solvents and prevent fluorescent resonance energy transfer, improving quantum efficiency and emission efficiency by forming a light converting layer between the color filter layer and the light emitting diode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a color filter layer is used to emit red, green, and blue colors in pixel regions, then full color display is achieved, but light efficiency is significantly reduced due to absorption of white light

Engineering Contradiction:

Improvelight efficiencyVSAvoidcolor filter layer absorption

Core Design Contradiction:

Illumination intensityVSEase of manufacture

Solution Approach 1:

The invention extracts and removes the color filter layer from the display device structure. Instead of using a white OLED with a color filter layer, the patent employs three separate sub-pixels with red, green, and blue emitting OLEDs, eliminating the need for light absorption and re-emission through color filters, thereby significantly improving light efficiency

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention segments the single white OLED into three separate color-specific OLEDs (red, green, and blue sub-pixels). Each sub-pixel independently emits its specific color without requiring a color filter layer, thus avoiding light absorption losses and improving overall light efficiency

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If a fine metal mask is used to form red, green, and blue emitting layers in pixel regions, then color display is achieved, but the method cannot be applied to large-sized OLED display devices

Engineering Contradiction:

Improveemitting layer formation precisionVSAvoidapplicability to large-sized devices

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The invention introduces a new fabrication approach that uses separate processing steps for each color sub-pixel rather than a single fine metal mask step. This intermediary method allows each color layer to be formed independently, enabling scalability to large-sized devices while maintaining manufacturing precision

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention transitions from a planar single-layer deposition approach to a multi-layer, multi-step fabrication process. By adding the dimension of sequential layer formation for each color, the method achieves both high precision and scalability for large-sized OLED displays

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If a white OLED emits white light that passes through color filter patterns, then color image display is achieved, but light efficiency is reduced due to wavelength-specific absorption

Engineering Contradiction:

Improvecolor filter layer structureVSAvoidenergy loss from light absorption

Core Design Contradiction:

Ease of manufactureVSUse of energy by moving object

Solution Approach 1:

The invention inverts the conventional approach by instead of filtering white light to produce colors, it directly generates specific colors through separate red, green, and blue OLEDs. This reversal eliminates the energy loss associated with filtering and re-emitting light, significantly improving energy efficiency

Inventive Principle:

Principle #13The other way round (Inversion)

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 significantly enhances light efficiency by minimizing absorption and maximizing emission of specific colors, improving the overall luminance and color purity of the OLED display device.

Implementation Method 1

one of the first and second ligands is a polar ligand, and the other of the first and second ligands is a non-polar ligand

Methodology Applied

Scientific EffectDipole-dipole interaction:

Implementation Method 2

one of the first and second ligands is a polar ligand, and the other of the first and second ligands is a non-polar ligand

Methodology Applied

Scientific EffectLondon dispersion force:

Implementation Method 3

prevent fluorescent resonance energy transfer

Methodology Applied

Scientific EffectFluorescent resonance energy transfer:

Data Source

PatentEP3474329A1Luminous body, light emitting film, light emitting diode and light emitting device having luminous body

Publication Date: 2019.04.24 LG DISPLAY CO LTD

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AI summary

A luminous body (100) includes: a first moiety (110) including a plurality of first ligands (116) combined to a surface of an inorganic emitting particle (111) ; and a second moiety (120) including silsesquioxanes connected to a second ligand (122) connected to the first ligand (116), wherein one of the first and second ligands is a polar ligand, and the other of the first and second ligands is a non-polar ligand.