Color Conversion Sheet Phosphor Diffusion Barrier
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Solution Overview
Problem
Organic phosphors used in liquid crystal display devices are prone to deterioration due to chemical or physical reactions with adjacent materials, leading to reduced photodurability and challenges in maintaining color gamut and luminance reliability.
Innovation Solution
A color conversion sheet is developed, featuring a first wavelength conversion layer with an organic phosphor dispersed in a resin matrix, a phosphor diffusion barrier layer with a specific solvent composition to prevent phosphor diffusion, and an adhesive layer. This configuration prevents chemical reactions and diffusion of the organic phosphor, ensuring stability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If organic phosphors are used to achieve wide color gamut and excellent brightness characteristics, then color conversion performance is improved, but photodurability deteriorates due to chemical or physical reactions with adjacent materials
Solution Approach 1:
The patent introduces a phosphor diffusion barrier layer as an intermediary between the organic phosphor-containing wavelength conversion layer and adjacent layers. This barrier layer prevents direct contact and chemical reactions between the organic phosphor and adjacent materials, thereby maintaining photodurability while preserving the brightness characteristics provided by the organic phosphor.
Solution Approach 2:
The patent employs a thin film barrier layer with specific solvent composition (Hildebrand solubility parameter difference >2 MPa^1/2) that acts as a protective shell around the organic phosphor. This thin film structure prevents phosphor deterioration through chemical reactions while maintaining the optical properties necessary for excellent brightness characteristics.
2Device complexity
If organic phosphors are used without barrier films, then manufacturing complexity is reduced, but color change increases due to phosphor deterioration
Solution Approach 1:
The patent uses a thin film phosphor diffusion barrier layer that adds minimal structural complexity while effectively preventing phosphor deterioration. The barrier layer's thin film nature keeps the overall device complexity low while providing sufficient protection against color change caused by phosphor chemical reactions.
Solution Approach 2:
The patent controls the solvent composition of the barrier layer by specifying that the Hildebrand solubility parameter difference between the solvent and resin matrix must be greater than 2 MPa^1/2. This parameter control ensures the barrier layer effectively prevents phosphor diffusion and chemical reactions, thereby maintaining color stability without requiring complex multi-layer structures.
3Illumination intensity
If cadmium-based nano-sized inorganic particles are used for quantum dot technology, then color gamut is improved, but environmental safety deteriorates and moisture vulnerability increases
Solution Approach 1:
The patent replaces cadmium-based quantum dots with organic phosphors that are environmentally safer. Although organic phosphors were initially considered to have shorter lifetimes due to moisture vulnerability, the patent addresses this by introducing a protective barrier layer, thereby achieving both environmental safety and sufficient durability.
Solution Approach 2:
The patent creates a composite structure combining organic phosphors with a specifically formulated barrier layer material. This composite approach leverages the environmental advantages of organic phosphors while the barrier layer compensates for their moisture vulnerability, achieving both wide color gamut and environmental safety.
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 deterioration of organic phosphors, maintaining low color change and excellent luminance reliability even under high temperature and high humidity conditions, thus enhancing the performance and longevity of liquid crystal display devices.
Implementation Method 1
a phosphor diffusion barrier layer positioned on one surface of the first wavelength conversion layer... the first phosphor diffusion barrier layer is formed from a composition containing a solvent having a Hildebrand solubility parameter
Implementation Method 2
an organic phosphor dispersed in a resin matrix... superior luminescence efficiency compared to nano-sized inorganic particles
Data Source
AI summary
A color conversion sheet according to the present invention includes a first wavelength conversion layer in which an organic phosphor is dispersed in a resin matrix, a first phosphor diffusion barrier layer positioned on one surface of the first wavelength conversion layer, and an adhesive layer positioned on one surface of the first phosphor diffusion barrier layer, wherein a Hildebrand solubility parameter of the first phosphor diffusion barrier layer satisfies a predetermined relationship between a Hildebrand solubility parameter of the resin matrix of the first wavelength conversion layer and a Hildebrand solubility parameter of a solvent contained in the first phosphor diffusion barrier layer, thereby resolving problems of changes in luminance characteristics and color change.