Red Phosphor Composition for Narrower Emission Spectrum
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Solution Overview
Problem
Current red phosphors used in light-emitting devices have unclear emission intensity and broad spectrum half widths, which affect conversion efficiency and color rendering, necessitating a phosphor with improved emission peak wavelength and narrower spectrum half width.
Innovation Solution
A phosphor with a specific crystal phase composition, including elements like Mo, W, Nb, and Ni, and a content of these elements within certain limits, is used to achieve a favorable emission peak wavelength and high emission intensity, integrated into light-emitting devices for improved color rendering and conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional red phosphors (S/CASN phosphors) are used in light-emitting devices, then the device can be manufactured with existing materials, but the spectrum half width is broad (80-90 nm) and emission intensity is unclear, resulting in poor conversion efficiency
Solution Approach 1:
The patent changes the chemical composition parameters of the red phosphor by introducing a specific element Z (from groups 5-10 periodic table) at controlled concentrations (1-1000 ppm). This compositional parameter change narrows the spectrum half width from 80-90 nm to 60-70 nm while enhancing emission intensity and conversion efficiency, resolving the contradiction between manufacturing feasibility and spectral precision.
Solution Approach 2:
The patent creates a composite phosphor material by combining the base red phosphor (Sr2Si5N8:Eu or CaAlSiN3:Eu) with trace amounts of element Z from the periodic table groups 5-10. This composite approach maintains the fundamental properties of the base phosphor while adding spectral narrowing and intensity enhancement effects, achieving both manufacturing compatibility and improved performance.
2Productivity
If the spectrum half width is reduced to improve conversion efficiency, then emission intensity may be compromised, but the patent achieves both narrow spectrum half width and high emission intensity
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: the concentration of element Z (1-1000 ppm), the host phosphor composition ratios, and the sintering conditions. This multi-parameter optimization achieves the counterintuitive result of narrowing the spectrum half width (improving conversion efficiency) while maintaining or enhancing emission intensity, resolving the apparent contradiction between these two performance metrics.
3Productivity
If existing red phosphors are used, then the light-emitting device can be produced with standard materials, but the emission peak wavelength and spectrum characteristics are not optimized for maximum conversion efficiency
Solution Approach 1:
The patent precisely controls the emission peak wavelength by adjusting the element Z concentration and host phosphor composition. This parameter control shifts and sharpens the emission peak to optimal wavelengths for maximum conversion efficiency, while maintaining manufacturability through standard synthesis procedures. The controlled addition of element Z acts as a spectral tuning mechanism.
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 phosphor achieves a favorable emission peak wavelength, narrow spectrum half width, and high emission intensity, enhancing color rendering and conversion efficiency in light-emitting devices, illumination devices, and indicator lamps for vehicles.
Implementation Method 1
a phosphor that emits red light and a phosphor that emits green light, with blue light from the blue LED chip as excitation light
Data Source
AI summary
A phosphor contains a crystal phase having a composition represented by RexMAaMBbMCcDdXe, and an element Z, in which a content of the element Z is 1,000 mass ppm or less, and the element Z includes at least one of Mo, W, Nb, Ta, Ni, Pt, or Ir. Regarding the composition, MA includes at least one of Ca, Sr, Ba, Na, K, Y, Gd, or La, MB includes at least one of Li, Mg, or Zn, MC includes at least one of Al, Si, Ga, In, or Sc, D is N (nitrogen) and/or O (oxygen), X includes at least one of F, Cl, Br, or I, and Re includes at least one of Eu, Ce, Pr, Tb, or Dy, and a, b, c, d, e, and x satisfy the specific expressions, respectively.