Quantum Dot Wavelength Sheets With Curved Barriers Against Dark Lines
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Solution Overview
Problem
Wavelength conversion sheets used in liquid crystal display devices suffer from the generation of dark regions such as black lines due to the degradation of quantum dots, which are prone to moisture and oxygen, leading to reduced yield and quality issues.
Innovation Solution
A wavelength conversion sheet with a specific layer configuration where the first and second protective films are asymmetrically disposed relative to the quantum dot-containing layer, featuring a curled shape convex on the outer side, and includes a first and second barrier layer with layers other than cured product layers in contact with the outer side, to prevent cracking and degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wavelength conversion sheet uses a quantum dot-containing layer protected by barrier films, then the light emission efficiency and color purity are improved, but dark regions such as black lines are generated on the surface over time due to barrier layer cracking
Solution Approach 1:
The patent applies asymmetry by making the layer configurations of the first and second protective films asymmetric with respect to the quantum dot-containing layer. Specifically, the first protective film has a first support and first barrier layer, while the second protective film has a second support and second barrier layer, with different arrangements. This asymmetric configuration prevents uniform stress distribution that would cause cracking, thereby suppressing dark region formation while maintaining protection of the quantum dots
Solution Approach 2:
The patent introduces a curled shape to the wavelength conversion sheet, making it convex on the outer side. This curvature compensates for stress-induced cracking by pre-distorting the structure in a controlled manner, allowing the barrier layers to accommodate thermal and mechanical stresses without cracking, thus preventing dark region formation while maintaining quantum dot protection
2Reliability
If the barrier layers are made thick to prevent degradation, then the protection against moisture and oxygen is improved, but the layer configuration becomes complex and manufacturing difficulty increases
Solution Approach 1:
The patent divides the protective structure into multiple thin barrier layers (first barrier layer and second barrier layer) rather than using a single thick barrier layer. Each barrier layer is positioned in different protective films with asymmetric configurations. This segmentation provides effective moisture and oxygen protection through multiple interfaces while keeping individual layers thin and manageable, reducing manufacturing complexity
Solution Approach 2:
The patent uses composite protective films consisting of multiple materials with different functions: support layers for mechanical strength, barrier layers for moisture and oxygen protection, and additional functional layers. This composite structure achieves superior protection against degradation while maintaining reasonable manufacturing complexity through the division of functions across different material layers
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 suppresses the generation of dark regions over time, maintaining the quality and yield of the wavelength conversion sheets by preventing barrier layer cracking and enhancing durability.
Implementation Method 1
The quantum dot has a higher light emission efficiency than the conventionally used phosphor using a rare earth ion as an activator, and can realize a high light emission efficiency of 90% or more. In addition, the emission wavelength of the quantum dot depends on the bandgap energy of the compound semiconductor fine particle quantized as described above
Implementation Method 2
it is preferable to protect the surfaces of both sides of a quantum dot-containing layer with a barrier film for a wavelength conversion sheet
Data Source
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AI summary
Provided is a wavelength conversion sheet that can suppress the generation of dark regions such as black lines over time. A wavelength conversion sheet in which a first protective film, a quantum dot-containing layer containing a quantum dot, and a second protective film are laminated in presented order, wherein when a direction in which the first protective film is positioned and a direction in which the second protective film is positioned, relative to the quantum dot-containing layer, are defined as an inner side and an outer side, respectively, the wavelength conversion sheet has a curled shape being convex on the outer side, a layer configuration of the first protective film and a layer configuration of the second protective film are asymmetrically disposed with respect to the quantum dot-containing layer, the first protective film comprises a first support and a first barrier layer, the second protective film comprises a second support and a second barrier layer, the wavelength conversion sheet comprises at least two or more layers containing a cured product of a curable resin composition, and a layer in contact with the outer side of the first barrier layer and a layer in contact with the outer side of the second barrier layer are each a layer other than the layers containing a cured product of a curable resin composition.