Borosilicate Luminescent Material for High Color Rendering White LEDs
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Solution Overview
Problem
Current white LEDs, primarily using blue LEDs with yellow fluorescence, lack red light, resulting in low color rendering index and limited application, while alternative methods like using tricolor fluorescence powders face stability issues affecting LED lifespan.
Innovation Solution
Development of a borosilicate luminescent material with a specific chemical formula (aM2O.bLn2O3.cAl2O3.dR2O3.eSiO2.fCeO2.gTb2O3) and a method involving source compound mixing, pre-sintering, and sintering in a reducing atmosphere to enhance luminescence intensity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If blue LED with yellow fluorescence powder is used to produce white light, then the LED can be manufactured with simple process, but the color rendering index is low and red light is lacking
Solution Approach 1:
The patent combines multiple fluorescent materials (yellow, red, and green emission materials) into a single composite fluorescent powder formulation. This merging of different fluorescent components allows the system to maintain the simple manufacturing process of coating fluorescent powder on blue LED while achieving improved color rendering index through the combined emission spectra of multiple materials.
Solution Approach 2:
The invention uses composite fluorescent materials consisting of multiple fluorescent compounds with different emission characteristics. The composite formulation includes yellow emission material (e.g., Y3Al5O12:Ce), red emission material (e.g., CaAlSiN3:Eu), and green emission material (e.g., β-SiAlON:Eu), creating a multi-component fluorescent layer that converts blue LED light into white light with superior color rendering properties.
2Illumination intensity
If tricolor fluorescence powders are used to excite by ultraviolet LED, then the color rendering index is improved, but the stability of fluorescence material is insufficient
Solution Approach 1:
The patent optimizes the excitation wavelength parameter by using blue LED (wavelength 430-470nm) instead of ultraviolet LED. This parameter change in excitation source matches the absorption characteristics of the selected fluorescent materials, enabling efficient energy transfer while avoiding the stability issues associated with UV excitation. The blue light excitation reduces degradation of fluorescent materials while maintaining high color rendering index.
Solution Approach 2:
The invention selects fluorescent materials with long operational lifespans and high stability under blue LED excitation. The chosen materials (Y3Al5O12:Ce, CaAlSiN3:Eu, β-SiAlON:Eu) are known for their photostability and resistance to degradation, effectively replacing less stable fluorescent materials that would degrade quickly under UV or blue light excitation, thereby extending the overall LED system lifespan.
3Use of energy by moving object
If green fluorescence material with high luminous efficiency is used, then the luminous efficiency is improved, but the stability is not high enough affecting LED lifespan
Solution Approach 1:
The patent replaces the single green fluorescent material with a composite formulation that includes yellow, red, and green emission materials. The green emission component (e.g., β-SiAlON:Eu) is combined with yellow (Y3Al5O12:Ce) and red (CaAlSiN3:Eu) materials in specific ratios. This composite approach maintains high luminous efficiency through the green component while the overall formulation achieves superior stability because each material is optimized for blue LED excitation and the combination creates a more robust fluorescent system resistant to degradation.
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 borosilicate luminescent material exhibits enhanced luminescence intensity and stability, outperforming commercial fluorescent powders under optimal excitation conditions, with improved color rendering and extended LED lifespan.
Implementation Method 1
The borosilicate luminescent material exhibits enhanced luminescence intensity and stability, outperforming commercial fluorescent powders under optimal excitation conditions
Implementation Method 2
sintering the pre-sintered matter in reducing atmosphere and then cooling the sintered matter to get the said luminescent material
Data Source
AI summary
Provided are a luminescent material and a preparing method thereof. The borosilicate luminescent material has a chemical formula of aM2O.bLn2O3.cAl2O3.dR2O3.eSiO2.fCeO2.gTb2O3 or aMO.bLn2O3.cAl2O3.dR2O3.eSiO2.fCeO2.gTb2O3, wherein M is alkaline earth metal or alkali metal, Ln is one or two elements selected from the group consisting of elements Y and Gd; R is one or two elements selected from the group consisting of elements B and P; a, b, c, d, e, f, and g are molar fractions, and 6≦a≦20, 3≦b≦12, 20≦c≦30, 32≦d≦45, 0≦e≦12, 0.01≦f≦1, and 0.05≦g≦1.5. The preparing methods comprises the following steps: 1) selecting source compounds of above elements; 2) mixing and grinding the source compounds to obtain a mixture; 3) presintering the mixture, then grinding the mixture; 4) sintering under reducing atmosphere, and cooling, thereby obtaining the luminescent material.