Spherical Quantum Dot Clusters for Backlight Light Extraction
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Solution Overview
Problem
The existing methods for improving light extraction efficiency and reducing thickness in wavelength conversion members for liquid crystal display devices result in decreased brightness due to unstructured clusters of quantum dots and increased quantum dot concentration, leading to emission efficiency and adhesive strength issues.
Innovation Solution
A wavelength conversion member with spherical clusters is achieved by mixing quantum dots with amino silicone and a monomer material, forming an emulsion, and curing both components to create a strong and efficient emission layer, where the quantum dots are dispersed in a spherical shape within a polymer matrix, enhancing light extraction and maintaining adhesive strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If clusters including quantum dots are made unstructured by crushing the cured product, then the manufacturing process is simplified, but the light extraction efficiency from the clusters decreases and brightness decreases
Solution Approach 1:
The patent applies spheroidality by forming spherical clusters of quantum dots instead of unstructured crushed clusters. The spherical shape is achieved by mixing quantum dots with amino silicone and a monomer material, then curing the mixture to form uniformly spherical clusters dispersed in a polymer matrix. This spherical structure improves light extraction efficiency while maintaining manufacturing simplicity, directly resolving the contradiction between ease of manufacture and brightness.
2Length of stationary object
If the thickness of the wavelength conversion layer is reduced to decrease overall device thickness, then the device becomes thinner, but the brightness and light extraction efficiency decrease
Solution Approach 1:
The patent uses composite materials by combining quantum dots with amino silicone and a monomer material to form spherical clusters, which are then dispersed in a polymer matrix. This composite structure allows the wavelength conversion layer to maintain high light extraction efficiency and brightness even at reduced thickness, as the spherical clusters provide efficient light scattering and extraction pathways within the thinner layer.
3Length of stationary object
If the content of quantum dots in the wavelength conversion layer is increased to reduce layer thickness, then the device becomes thinner, but the emission efficiency of quantum dots decreases and brightness decreases
Solution Approach 1:
The spherical cluster structure concentrates quantum dots in discrete spherical regions dispersed throughout the polymer matrix, rather than uniformly distributing them throughout the layer. This allows achieving the desired optical effect with lower overall quantum dot content, maintaining emission efficiency while enabling thinner layer design. The spherical geometry optimizes the distribution density of quantum dots.
4Length of stationary object
If the wavelength conversion layer is made thinner to reduce device thickness, then the device becomes thinner, but the adhesive strength decreases and barrier films may peel
Solution Approach 1:
The composite structure of spherical clusters (quantum dots + amino silicone + monomer) dispersed in a polymer matrix provides enhanced mechanical properties. The spherical clusters act as reinforcement elements within the thin polymer layer, improving adhesive strength and preventing barrier film peeling even when the overall layer thickness is reduced to several tens of micrometers.
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 approach results in a wavelength conversion member with improved light extraction efficiency, sufficient strength, and reduced thickness, maintaining high brightness and emission efficiency while preventing peeling of barrier films, thus enhancing the performance of liquid crystal display devices.
Implementation Method 1
when excitation light emitted from a backlight is incident on a wavelength conversion member including quantum dots, the quantum dots are excited to emit fluorescence
Implementation Method 2
the wavelength conversion layer comprises a second cured product and a first cured product that is dispersed as spheres in the second cured product
Data Source
AI summary
The invention provides a wavelength conversion member including a wavelength conversion layer which includes a second cured product and a first cured product dispersed as spheres in the second cured product, the first cured product being obtained by curing a first polymerizable composition including a quantum dot and a first polymerizable compound, and the second cured product being obtained by curing a second polymerizable composition including a second polymerizable compound. The invention further provides a backlight unit and a liquid crystal display device including the wavelength conversion member.