CaAlSiN3:Eu Phosphor Magnesium Barium Doping for Red Light Emission
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Solution Overview
Problem
Current white light emitting devices using YAG:Ce phosphors with blue light-emitting semiconductor elements suffer from inadequate red light emission, leading to insufficient color rendering and brightness, and existing nitride phosphors face issues with heat resistance and luminescence efficiency.
Innovation Solution
A novel red phosphor is developed by adding specific amounts of magnesium and barium to CaAlSiN3:Eu, with a formula of CapSrqMm-Aa-Bb—Ot—Nn:Eur, where M is beryllium or zinc, A is aluminum or gallium, and B is silicon or germanium, to enhance luminescence brightness and chromaticity, forming a high brilliance light emitting device with a semiconductor light-emitting element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If YAG:Ce phosphor is used with blue light-emitting semiconductor element, then the device structure is simple and manufacturing is easy, but the color rendering properties and color saturation are insufficient due to deficient red light emission
Solution Approach 1:
The patent combines multiple phosphors (YAG:Ce phosphor and red light-emitting phosphor) into a single luminescent system. The phosphor layer contains both yellow-emitting YAG:Ce particles and red-emitting phosphor particles, which together with the blue semiconductor light source produce white light with improved color rendering properties and color saturation.
Solution Approach 2:
The patent uses composite phosphor materials consisting of Y3Al5O12:Ce (yellow phosphor) combined with red light-emitting phosphors such as Sr2Si5N8:Eu, CaAlSiN3:Eu, or sialon phosphors. This composite approach allows the system to emit both yellow and red light components, significantly improving color rendering while maintaining ease of manufacture through a single phosphor layer application.
2Illumination intensity
If Sr2Si5N8:Eu phosphor is used to emit red light, then the color rendering properties are improved, but the brightness decreases after long term usage due to poor heat resisting properties
Solution Approach 1:
The patent optimizes the composition parameters of the red light-emitting phosphor by adjusting the ratios of Sr, Si, N, and Eu elements, and by controlling particle size and crystal structure. These parameter changes enhance the heat resistance and stability of the phosphor while maintaining its red light emission properties, thereby improving long-term brightness stability.
Solution Approach 2:
The patent creates a multi-component phosphor system where different phosphors are distributed throughout the luminescent layer. The red light-emitting phosphor particles are dispersed within the YAG:Ce phosphor matrix, allowing each component to contribute its specific properties while the overall system achieves both color rendering and stability.
3Reliability
If sialon phosphor is used to emit red light, then the durability is improved, but the luminescence brightness is clearly insufficient
Solution Approach 1:
The patent merges sialon phosphor with other red light-emitting phosphors (such as Sr2Si5N8:Eu or CaAlSiN3:Eu) to create a composite phosphor system. This combination allows the sialon phosphor to provide durability and heat resistance, while the other phosphors contribute higher luminescence brightness, achieving both reliability and brightness requirements.
4Reliability
If CaAlSiN3:Eu phosphor is used to emit red light, then the durability and brightness are improved compared to sialon phosphor, but the luminescence brightness is still insufficient for high efficiency light emitting devices
Solution Approach 1:
The patent uses composite phosphor materials where CaAlSiN3:Eu is combined with YAG:Ce phosphor and potentially other red light-emitting phosphors. This composite approach allows the system to leverage the durability of CaAlSiN3:Eu while achieving higher overall luminescence brightness through the synergistic effects of multiple phosphors with complementary emission characteristics.
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 luminescence brightness and improved color rendering with specific magnesium and barium content, resulting in a high brilliance light emitting device suitable for various applications, including LEDs, with enhanced color coordinates and efficiency.
Implementation Method 1
the phosphor absorbs and converts the light emitted from the semiconductor light-emitting element
Implementation Method 2
the phosphor absorbs blue light and emit red light
Data Source
AI summary
The present invention provides a phosphor, including a constituent having the formula CapSrqMm-Aa-Bb—Ot—Nn:Eur, wherein M selected from the group consisting of beryllium and zinc; A selected from the group consisting of aluminum, gallium, indium, scandium, yttrium, lanthanum, gadolinium and lutetium; B selected from a group consisting of silicon, germanium, tin, titanium, zirconium and hafnium; 0<p<1; 0<q<1; 0≦m≦1; 0≦t≦0.3; 0.00001≦r≦0.1; a=1, 0.8≦b≦1.2; and 2.7≦n≦3.1; and the phosphor contains 20˜1500 ppm of magnesium and/or 40˜5000 ppm of barium. A high brightness phosphor emitting in the 600˜680 nm region is achieved by means of adjusting the proportion of each of the elements of the phosphor, and in combination with controlling concentration of the magnesium and barium of the phosphor within a specific range. In addition, the present invention provides a light emitting device provided with high brilliance.