Phosphor Composition for High Brightness White Light
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Solution Overview
Problem
Current white light emitting devices using YAG phosphor and semiconductor light emitting elements suffer from poor color hue and low brightness due to inefficient light conversion and lack of red light emission, limiting their application in high-brightness light sources.
Innovation Solution
A phosphor with the composition formula AaSi5OtNn:EuZ, where A is selected from Be, Mg, Ca, Sr, and Ba, and containing Mo in specific ppm ranges, is used to enhance luminous brightness and chromaticity, allowing for efficient conversion of excitation light into a wider range of wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If YAG phosphor (Y3Al5O12:Ce) is used for white light emission, then the light emitting device achieves compact size and lower power consumption, but the chromaticity coordinates are limited to the junction line between blue and yellow lights, resulting in poor color rendering and insufficient red light
Solution Approach 1:
The patent combines YAG:Ce phosphor with a red-emitting phosphor (Sr2Si5N8:Eu or CaAlSiN3:Eu) to create a mixed phosphor system. This merging allows the light emitting device to achieve both the compact size and low power consumption of YAG phosphor and the extended chromaticity range with red light emission from the red phosphor, thereby resolving the contradiction between illumination intensity and chromaticity versatility.
Solution Approach 2:
The invention uses composite phosphor materials by combining multiple phosphor compounds (Y3Al5O12:Ce and Sr2Si5N8:Eu or CaAlSiN3:Eu) in a single light emitting device. This composite approach enables the device to simultaneously achieve high luminous brightness from YAG phosphor and expanded color rendering with red light from the red-emitting phosphor, addressing both requirements of the technical contradiction.
2Productivity
If Y3Al5O12:Ce phosphor is used with blue light semiconductor light emitting element, then the device achieves higher emitting efficiency and lower cost, but the excitation spectrum area is inconsistent with the light emitting region, resulting in poor conversion efficiency
Solution Approach 1:
The patent introduces a red-emitting phosphor with different excitation spectrum characteristics to complement the YAG:Ce phosphor. By carefully selecting the red phosphor material and its excitation spectrum, the invention optimizes the overall light conversion efficiency while maintaining compatibility with the blue light semiconductor light emitting element, thereby reducing energy loss from spectrum mismatch.
3Reliability
If Sr2Si5N8:Eu phosphor is used to emit red light, then the phosphor achieves adequate durability, but the luminous brightness is poor, limiting its application
Solution Approach 1:
The invention merges Sr2Si5N8:Eu red phosphor with YAG:Ce phosphor in a composite light emitting device. This combination allows the system to benefit from the durability of Sr2Si5N8:Eu phosphor while the YAG:Ce phosphor contributes high luminous brightness, thereby resolving the contradiction between reliability and illumination intensity.
Solution Approach 2:
The patent creates a composite phosphor system combining Sr2Si5N8:Eu and Y3Al5O12:Ce, where the Sr2Si5N8:Eu provides durability and red light emission, while the Y3Al5O12:Ce provides high brightness and yellow light emission. This composite material approach enables simultaneous achievement of both durability and high luminous brightness.
4Reliability
If CaAlSiN3:Eu phosphor is used, then the phosphor achieves better durability and brightness than sialon phosphor, but the luminous brightness is still insufficient for high efficiency light emitting devices
Solution Approach 1:
The invention combines CaAlSiN3:Eu phosphor with YAG:Ce phosphor to create a mixed light emitting system. This merging allows the device to achieve the durability of CaAlSiN3:Eu phosphor and the high luminous brightness of YAG:Ce phosphor, thereby resolving the contradiction between reliability and illumination intensity.
Solution Approach 2:
The patent uses composite phosphor materials by combining CaAlSiN3:Eu and Y3Al5O12:Ce, where the CaAlSiN3:Eu provides durability and red light emission, while the Y3Al5O12:Ce provides high brightness. This composite approach enables simultaneous achievement of both durability and high luminous brightness, overcoming the limitations of single phosphor materials.
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 higher luminous brightness and improved chromaticity coordinates, enabling the production of high-brightness light emitting devices with enhanced color rendering and saturation properties.
Implementation Method 1
The phosphor can absorb and convert light emitted from the semiconductor light emitting element
Data Source
AI summary
A phosphor and a light emitting device are provided. The phosphor comprises a composition having a formula of AaSi5OtNn:EuZ. A is selected from the group consisting of Be, Mg, Ca, Sr and Ba. 1.7<a<2.5. 0≦t<1, 7<n<9. 0.001<z<0.3. The phosphor has Mo of 10 ppm-500 ppm.