Phosphor Compositions for High CRI LED Lighting
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Solution Overview
Problem
Current phosphor compositions used in LEDs and other light sources do not achieve high enough color rendering indices (CRI) and flexible emission colors, particularly for applications requiring high CRI values similar to incandescent lamps, and there is a need for additional phosphor compositions for various lighting applications.
Innovation Solution
Development of novel phosphor compositions with the formula EueMmAaGgQqNnXx, where M, A, G, and X are specific elements, and the stoichiometric coefficients e, m, a, g, q, n, and x are within defined ranges, allowing for customization of emission colors and enhanced quantum efficiency, which are used in conjunction with LED chips to produce white or colored light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional phosphor compositions are used in LEDs, then the device structure is simple and manufacturing is easy, but the color rendering index (CRI) is insufficient and emission colors are not flexible enough
Solution Approach 1:
The patent employs composite phosphor materials with multi-element compositions including rare earth elements (Eu, Dy, Tb), alkaline earth metals (Sr, Ba, Ca), and various anions (SiO4, PO4, SO4) to achieve flexible emission colors and high CRI. The composite structure allows tuning of emission characteristics by varying element ratios and combinations, resolving the contradiction between performance flexibility and compositional simplicity.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the stoichiometric ratios of elements within the phosphor composition (e.g., varying Eu content, Sr/Ba ratios, SiO4/PO4 proportions) to control emission color and CRI. This approach enables flexible color tuning and high CRI achievement without fundamentally changing the basic phosphor structure, balancing adaptability with manufacturing feasibility.
2Reliability
If conventional phosphor compositions are used, then manufacturing processes are straightforward, but quantum efficiency and color rendering performance are insufficient
Solution Approach 1:
The patent optimizes quantum efficiency by precisely controlling synthesis parameters including firing temperature (1000-1500°C), atmosphere (oxidizing, reducing, or neutral), and stoichiometric ratios of precursor materials. These parameter adjustments enhance the reliability and performance of the phosphor while maintaining compatibility with existing ceramic synthesis methodologies, balancing performance improvement with manufacturing ease.
Solution Approach 2:
The composite phosphor structure incorporating multiple elements in specific ratios creates synergistic effects that enhance quantum efficiency. The presence of host lattice materials (e.g., Sr2SiO4, Ba2SiO4) combined with activator ions (Eu2+, Dy3+) and co-activators (Tb3+, Mn2+) produces high-efficiency luminescence while using conventional solid-state reaction techniques for synthesis.
3Reliability
If simple phosphor compositions are used, then production costs are low and manufacturing is easy, but the color rendering index cannot reach incandescent-level performance
Solution Approach 1:
The patent achieves incandescent-level CRI (Ra > 95) through composite phosphor formulations combining multiple rare earth elements and alkaline earth metals in optimized ratios. The multi-element composition enables broad spectral coverage across visible wavelengths, providing superior color rendering while using standard ceramic processing techniques to manage material complexity.
Solution Approach 2:
The patent tunes the CRI by adjusting the concentrations and ratios of specific elements within the phosphor composition, particularly the relative amounts of Eu, Dy, Tb, Sr, Ba, and Ca. By optimizing these compositional parameters, the invention achieves high CRI performance comparable to incandescent lighting while maintaining practical manufacturing considerations.
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 novel phosphor compositions achieve higher quantum efficiency and customizable emission colors, enabling the production of white light with improved color rendering indices, such as a CRI of 97 and a correlated color temperature (CCT) below 4500K, surpassing the performance of existing technologies.
Implementation Method 1
A phosphor is a luminescent material that absorbs radiation energy in a portion of the electromagnetic spectrum and emits energy in another portion of the electromagnetic spectrum
Implementation Method 2
The phosphor absorbs a portion of the radiation emitted from the LED and converts the absorbed radiation to a yellow-green light
Data Source
AI summary
Phosphor compositions having the formula EueMmAaGgQqNnXx, where M is at least one of Be, Mg, Ca, Sr, Ba, Cd, Sn, Pb or Zn; A is at least one of B, Al, Ga, In, Bi, Sc, Y, La or a rare earth element other than Eu; G is at least one of Si or Ge; Q is at least one of O, S, and Se; X is at least one of F, Cl, Br and I; 0<e<2, 0<m<2, 0<=a<1, 0<g<1, 0<q<4, 0<=n<2, 0<=x<2, and 2e+2m+3a+4g=2q+3n+x; and light emitting devices including a light source and the above phosphor. Also disclosed are blends of EueMmAaGgQqNnXx and one or more additional phosphors and light emitting devices incorporating the same.