Eu2+-Activated Oxyhalide Phosphors for High Color Gamut Displays
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Solution Overview
Problem
Current light-emitting devices based on semiconductor elements and phosphors fail to achieve high color gamut and brightness simultaneously, particularly in small-sized LCD backlights, where a color gamut of about 65% (NTSC ratio) is insufficient, and there is a need for phosphors that efficiently absorb blue radiation and enhance quantum efficiency for improved color rendering in white light emitting devices.
Innovation Solution
Development of blue and green-emitting Eu2+-activated oxyhalide phosphors with specific formulas, such as M3SiO3X4:Eu2+, M5Si3O9X4:Eu2+, M1.64Si0.82O3.1X0.36:Eu2+, M10Si3O9X14:Eu2+, and M2SiO3X2:Eu2+, where M is Ba, Ca, or Sr, and X is Cl or Br, which are radiationally coupled with semiconductor light sources to enhance spectral characteristics and quantum efficiency for LED applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional phosphors ((Y,Gd)3(Al, Ga)5O12:Ce3+ or (Sr,Ba,Ca)2SiO4:Eu2+) are used in light-emitting devices, then the device structure is simple and easy to manufacture, but the color gamut is limited to about 65% (NTSC ratio)
Solution Approach 1:
The patent changes the chemical composition parameters of the phosphor material by incorporating halide ions (Cl-, Br-, I-) into the oxyhalide structure M3SiO3X4, M5Si3O9X4, M10Si3O9X14, or M2SiO3X2 where M = Ba, Ca, or Sr. This compositional parameter change enables the phosphor to achieve superior color rendering properties and higher color gamut (exceeding 65% NTSC ratio) while maintaining manufacturability through conventional ceramic processing techniques.
Solution Approach 2:
The patent develops composite oxyhalide phosphor materials with the general formula A-M3SiO3X4, A-M5Si3O9X4, A-M10Si3O9X14, or A-M2SiO3X2 where A represents alkaline earth metal atoms (Ba, Ca, Sr). These composite materials combine multiple elements in specific ratios to achieve optimized optical properties, including high quantum efficiency and improved color gamut, while remaining compatible with existing manufacturing processes.
2Illumination intensity
If phosphors with improved color rendering are developed, then the color gamut and quantum efficiency are enhanced, but the device complexity increases
Solution Approach 1:
The patent develops oxyhalide phosphors with the formulas A-M3SiO3X4, A-M5Si3O9X4, A-M10Si3O9X14, or A-M2SiO3X2 that serve multiple functions simultaneously: they provide high quantum efficiency, superior color rendering, and enhanced color gamut (exceeding 65% NTSC ratio). This multi-functionality allows a single phosphor material to replace what would traditionally require multiple phosphors, thereby simplifying the overall device structure while achieving improved performance.
3Use of energy by moving object
If blue radiation absorption is enhanced for improved quantum efficiency, then the quantum efficiency increases, but the spectral characteristics become more difficult to control
Solution Approach 1:
The patent utilizes parameter changes in the phosphor composition, specifically varying the halide ion type (Cl-, Br-, I-) and the alkaline earth metal (Ba, Ca, Sr) ratios in the formulas A-M3SiO3X4, A-M5Si3O9X4, A-M10Si3O9X14, or A-M2SiO3X2. These parameter adjustments enable precise control over the absorption spectrum and emission characteristics, allowing optimization of quantum efficiency for blue radiation while maintaining controllable and desirable spectral properties for various lighting applications.
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 described phosphors achieve high quantum efficiency and desirable spectral characteristics, enabling improved color rendering and increased color gamut in lighting and display applications, particularly in LED devices, with applications in 405 nm LED packages and high gamut LCDs, achieving desired effects on CRI and LPW when mixed with other LED phosphors.
Implementation Method 1
blue and green-emitting Eu2+-activated oxyhalide phosphors... radiationally coupled with semiconductor light sources to enhance spectral characteristics and quantum efficiency
Data Source
AI summary
Blue and green-emitting Eu2+-activated oxyhalide phosphors of formula A-E may be used in devices for lighting or display applications:A. M3SiO3X4:Eu2+;B. M5Si3O9X4:Eu2+;C. M1.64Si0.82O3.1X0.36:Eu2+;D. M10Si3O9X14:Eu2+;E. M2SiO3X2:Eu2+; andwhereinM is Ba, Ca, Sr, or a mixture thereof;X is Cl or Br, or a mixture thereof.