Wavelength Conversion Member Fluoride Phosphor Quantum Dots
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Solution Overview
Problem
Current light-emitting devices with wavelength conversion members face challenges in achieving high color purity and uniformity, particularly in liquid crystal display applications, due to variations in fluoride phosphor particle size and distribution, leading to fluctuations in luminescent color and excitation efficiency.
Innovation Solution
A wavelength conversion member comprising a fluoride phosphor with specific elemental composition and particle size distribution, combined with quantum dots and a resin, is used to create a uniform luminescent layer that suppresses non-uniformity and enhances chromaticity, featuring fluoride particles with an average size between 0.1 μm and 10 μm and a maximum size up to 18 μm, and quantum dots with a chalcopyrite-type structure for improved emission peak characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If fluoride phosphor particles are used for wavelength conversion, then color purity is improved, but particle size variation causes non-uniform luminescent color and excitation efficiency
Solution Approach 1:
The patent specifies precise particle size parameters for fluoride phosphor (average 0.1-10 μm, maximum 18 μm) and quantum dots (median diameter 3-15 nm) to optimize both color purity and uniformity. By controlling these physical parameters within defined ranges, the invention resolves the contradiction between achieving high color purity and maintaining particle size uniformity for consistent luminescent properties.
Solution Approach 2:
The invention creates a composite wavelength conversion layer combining fluoride phosphor particles with quantum dots (perovskite-type crystalline nanoparticles) in a resin matrix. This composite structure leverages the narrow emission peak of quantum dots to enhance color purity while the fluoride phosphor provides broad-spectrum excitation, together achieving both color purity and uniformity that neither material could achieve alone.
2Illumination intensity
If quantum dots with narrow emission peak are used, then color purity is improved, but manufacturing complexity increases
Solution Approach 1:
The patent merges fluoride phosphor and quantum dots into a single integrated wavelength conversion layer, eliminating the need for separate conversion layers for different wavelength ranges. This unified structure simplifies manufacturing compared to multi-layer approaches while maintaining the narrow emission peak benefits of quantum dots for high color purity.
Solution Approach 2:
The quantum dots in the invention serve multiple functions: they provide narrow emission peak for color purity, absorb blue light from the light-emitting element, and when combined with fluoride phosphor, enable efficient wavelength conversion across multiple spectra. This multi-functionality reduces the need for additional components, simplifying the overall device structure.
3Stability of the object's composition
If fluoride phosphor with specific composition is used, then luminescent color uniformity is improved, but material selection complexity increases
Solution Approach 1:
The patent defines specific compositional parameters for fluoride phosphor (elements M from Group 4, 13, or 14; alkali metal; Mn; F with precise molar ratios) to ensure luminescent color uniformity. By establishing these quantitative compositional guidelines, the invention achieves stable luminescent properties while providing clear manufacturing specifications that reduce material selection complexity.
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 achieves a color reproduction range greater than 85% of the BT2020 standard on a CIE chromaticity diagram, reducing color unevenness and improving luminance by ensuring uniform fluoride phosphor distribution and optimized quantum dot emission, thereby enhancing the performance of light-emitting devices.
Implementation Method 1
a wavelength conversion member in which a light-emitting element and a wavelength conversion member are combined
Implementation Method 2
a perovskite-type nanoparticle (also referred to as a quantum dot) that expresses a quantum size effect is known. The quantum size effect refers to a phenomenon in which each of a conduction band and a valence band considered to be continuous in bulk particles becomes discrete when the particle size is reduced to a nano size, and the band gap energy changes in accordance with the particle size.
Data Source
AI summary
A wavelength conversion member including a wavelength conversion layer containing a fluoride phosphor, quantum dots, a surfactant, and a resin. The fluoride phosphor contains fluoride particles having a specific composition and having particle size values within specific ranges. The quantum dots include at least one selected from a first crystalline nanoparticle and a second crystalline nanoparticle. The first crystalline nanoparticle has a specific composition. When irradiated with light having a wavelength of 450 nm, the first crystalline nanoparticle emits light having an emission peak at a wavelength in a range from 510 nm to 535 nm, and a full width at half maximum of the emission peak of the first crystalline nanoparticle is in a range from 10 nm to 30 nm. The second crystalline nanoparticle includes a chalcopyrite-type crystalline structure, and a full width at half maximum of the emission peak of the second crystalline nanoparticle is 45 nm or less.