Bromine-Containing Phosphor for High Color Rendering White LEDs
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Solution Overview
Problem
Current white LEDs based on YAG phosphors have poor color rendering properties and high color temperature, limiting their ability to accurately represent object colors under illumination.
Innovation Solution
A phosphor composition comprising at least 10 atomic percent bromine, silicon, or germanium, a metal element, and an activator like europium, which absorbs near-UV or blue radiation and emits in a tunable green or orange-red spectrum, improving color rendering and reducing yellow region emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If YAG phosphor is used in white LEDs, then the LED structure is simple and manufacturing is easy, but the color rendering properties are poor and color temperature is too high
Solution Approach 1:
The patent employs a composite phosphor system combining Y3Al5O12:Ce3+ (YAG) with Sr2Si5N8:Eu2+ and BaMgAl10O17:Eu2+ (BAM). This composite approach allows the system to maintain the structural simplicity and ease of manufacture of YAG while adding components that provide improved color rendering properties, specifically enhancing red and green spectral regions to achieve better overall color accuracy in white LED illumination
Solution Approach 2:
The patent modifies the phosphor composition parameters by introducing additional phosphor materials with specific emission characteristics. By adjusting the ratios and combinations of YAG, Sr2Si5N8:Eu2+, and BAM phosphors, the system achieves lower color temperature and improved color rendering index while maintaining compatibility with standard blue LED chips, thus resolving the contradiction between manufacturing simplicity and color rendering quality
2Device complexity
If YAG phosphor is used to generate white light, then the LED structure remains simple, but the spectral distribution provides poor color rendering capability
Solution Approach 1:
The patent creates a composite phosphor blend comprising Y3Al5O12:Ce3+ combined with Sr2Si5N8:Eu2+ and BaMgAl10O17:Eu2+. This composite structure maintains relative device simplicity while the synergistic combination of phosphors with different emission spectra (yellow-green from YAG, red from Sr2Si5N8:Eu2+, and blue-green from BAM) provides comprehensive spectral coverage for improved color rendering index without significantly increasing device complexity
Solution Approach 2:
The patent applies local quality enhancement by strategically selecting phosphor materials that target specific spectral deficiencies. The Sr2Si5N8:Eu2+ phosphor specifically addresses the red region deficiency, while BAM addresses the blue-green region, creating localized spectral enhancements that collectively improve overall color rendering while maintaining relatively simple device architecture
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 composition enhances color rendering properties by producing a blue-shifted emission spectrum, improving red-green contrast and enabling the creation of white light with better color accuracy and lower color temperature.
Implementation Method 1
A phosphor composition comprising at least 10 atomic percent bromine, silicon, or germanium, a metal element, and an activator like europium, which absorbs near-UV or blue radiation and emits in a tunable green or orange-red spectrum
Data Source
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AI summary
A phosphor composition is disclosed. A phosphor composition, comprises at least 10 atomic % bromine; silicon, germanium or combination thereof; oxygen; a metal M, wherein M comprises zinc (Zn), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), or combinations thereof; and an activator comprising europium. The phosphor composition is formed from combining carbonate or oxides of metal M, silicon oxide, and europium oxide; and then firing the combination. A lighting apparatus including the phosphor composition is also provided. The phosphor composition may be combined with an additional phosphor to generate white light.