Fluoride Phosphor Particle Control for Stable White LED Emission
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Solution Overview
Problem
The existing white LEDs using K2SiF6:Mn4+ phosphor face issues with unstable brightness and yield, leading to varying light emission characteristics in light emitting devices such as backlights and lighting fixtures.
Innovation Solution
A fluoride phosphor with a specific composition represented by A2M(1-n)F6:Mn4+n, where A is an alkali metal element like potassium and M is silicon or other tetravalent elements, with controlled bulk density, mass median diameter, and particle size distribution, ensuring stable and efficient light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If K2SiF6:Mn4+ phosphor is used to improve color rendering and color reproducibility, then color rendering is improved, but light emission characteristics become unstable and brightness varies significantly
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution (D50: 10-30 μm, span: 1.2 or less) and bulk density (0.83-1.56 g/cm³) of the K2SiF6:Mn4+ phosphor. These parameter optimizations stabilize the light emission characteristics while maintaining excellent color rendering, resolving the contradiction between color quality and emission stability.
2Use of energy by moving object
If Eu2+ activated nitride or oxynitride phosphor is used to achieve high fluorescence conversion efficiency, then fluorescence efficiency is improved, but emission spectrum becomes broad and brightness is reduced
Solution Approach 1:
The patent employs color changes by selecting Mn4+ as the activation element instead of Eu2+, which fundamentally changes the emission characteristics. Mn4+ provides sharp red emission with narrow half-value width, maintaining high brightness while achieving excellent color rendering, thus resolving the contradiction between efficiency and brightness.
3Use of energy by moving object
If phosphor with broad emission spectrum is used to achieve high fluorescence efficiency, then fluorescence efficiency is improved, but color reproduction range becomes narrow for display applications
Solution Approach 1:
The patent uses color changes by implementing Mn4+ activation which produces a sharp emission spectrum with narrow half-value width. This sharp spectral profile expands the color reproduction range for display applications while maintaining high fluorescence efficiency, resolving the contradiction between efficiency and color gamut.
4Ease of manufacture
If existing fluoride phosphor is used to maintain simple composition, then manufacturing is simplified, but external quantum efficiency is insufficient and yield is poor
Solution Approach 1:
The patent applies parameter changes by optimizing the particle size distribution (D50: 10-30 μm, span: 1.2 or less) and bulk density (0.83-1.56 g/cm³) parameters of the fluoride phosphor. These parameter optimizations significantly improve external quantum efficiency and production yield while maintaining the simplicity of the K2SiF6:Mn4+ composition, resolving the contradiction between manufacturing ease and productivity.
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 fluoride phosphor achieves stable production of white LEDs with improved external quantum efficiency and consistent light emission characteristics, enhancing the performance and yield of light emitting devices.
Implementation Method 1
the red phosphor obtained by activating with dissolving Mn4+ in a fluoride crystal such as K2SiF6 is efficiently excited by blue light and has a sharp emission spectrum with a narrow half-value width
Implementation Method 2
A fluoride phosphor having a composition represented by the following general formula (1), which is efficiently excited by blue light and has a sharp emission spectrum with a narrow half-value width
Data Source
AI summary
Provided is a fluoride phosphor that has a good external quantum efficiency and is suitable for stably producing white LEDs. The fluoride phosphor having a composition represented by a general formula (1), a bulk density of 0.80 g/cm3 or more, and a mass median diameter (D50) of 30 μm or less: general formula: A2M(1-n)F6:Mn4+n (1), wherein 0<n≤0.1, the element A is one or more alkali metal elements including at least K, and the element M is a simple substance of Si, a simple substance of Ge, or a combination of Si and one or more elements selected from the group consisting of Ge, Sn, Ti, Zr, and Hf.