Garnet Phosphor Thermal Quenching Reduction
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Solution Overview
Problem
Conventional white light sources using YAG phosphors and blue LEDs face limitations in chromaticity range due to thermal quenching, which restricts the range of colors that can be achieved, and existing yellow phosphors like BaY1.92Al4SiO12:Ce0.08 have limited thermal stability and light emission retention.
Innovation Solution
A garnet-type phosphor with a specific crystal structure formula BaaY3-a-bAl5-aSiaO12:Ceb, where a and b are within certain ranges, is developed, which exhibits improved light emission and temperature characteristics, allowing for a broader chromaticity range when combined with blue LEDs, and is encapsulated in a resin with thermal conduction powder for enhanced heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If YAG phosphor is used for white light source, then the light source achieves high luminance, but thermal quenching occurs leading to decreased efficiency
Solution Approach 1:
The patent modifies the crystal lattice parameters of the YAG phosphor by incorporating Ba and Si elements to form a solid solution with formula BaY1.92Al4SiO12:Ce0.08. This changes the lattice size and structure, reducing thermal quenching effects and improving temperature characteristics while maintaining high luminance output
Solution Approach 2:
The patent creates a composite phosphor material by combining multiple elements (Ba, Y, Al, Si, O, Ce) in specific ratios to form a new solid solution compound. This composite structure integrates the benefits of different elements: Ba and Si improve thermal stability, Ce provides luminescence, and the YAG framework maintains structural integrity at high temperatures
2Reliability
If BaY1.92Al4SiO12:Ce0.08 phosphor is used, then temperature characteristics improve, but chromaticity range becomes limited
Solution Approach 1:
The patent systematically varies the compositional parameters (Ba content, Si content, Ce content) within the garnet structure to tune both the temperature characteristics and chromaticity properties. By adjusting the ratios of these elements, the patent achieves a balance between thermal stability and chromaticity range, expanding the applicable color temperature range while maintaining reliability
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 new phosphor achieves a dominant wavelength within 567 nm to 572 nm, improving light emission efficiency and retention, and when integrated into a light emitting module, it produces white light with desired chromaticity coordinates suitable for applications like vehicle headlamps, while maintaining mechanical strength and heat dissipation performance.
Implementation Method 1
A phosphor according to one aspect of the present disclosure has a crystal structure of a garnet type and is expressed by a general formula BaaY3-a-bAl5-aSiaO12:Ceb
Implementation Method 2
The fluorescent member may include a resin transparent to visible light and a phosphor encapsulated in the resin
Data Source
AI summary
A phosphor has a crystal structure of a garnet type and is expressed by a general formula BaaY3-a-bAl5-aSiaO12:Ceb (wherein a and b are values within a range that satisfies 12.0113≤A+0.036b−0.003a≤12.0153, when A denotes a lattice size of the crystal structure, a [mol] denotes an amount of Ba incorporated in solid solution, and b [mol] denotes an amount of Ce incorporated in solid solution).