Phosphor Powder Blue Light Conversion Efficiency
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Solution Overview
Problem
The phosphor disclosed in existing patents has room for improvement in terms of blue light conversion efficiency, specifically in increasing internal quantum efficiency.
Innovation Solution
A phosphor powder with phosphor particles represented by the formula Mx(Si, Al)2(N, O)3±y, where M is Li and one or more alkaline earth metal elements, with a Si/Al atomic ratio of 1.5 to 6, O/N atomic ratio of 0 to 0.1, 5 to 50 mol % Li, and 0.5 to 10 mol % Ce, and a diffuse reflectance of 88% to 99.9% at 700 nm, is developed to enhance blue light conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the phosphor composition is modified to improve blue light conversion efficiency, then internal quantum efficiency increases, but the diffuse reflectance and stability may be compromised
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the phosphor material. Specifically, it defines the general formula Mx(Si, Al)2(N, O)3±y with constrained ranges for x (0.5-1.5) and y (0.01-0.3), and specifies atomic ratio ranges for Si/Al (1.2-6.0) and O/N (0.0-0.15). This systematic parameter optimization enables simultaneous achievement of high internal quantum efficiency (≥85%) and stable diffuse reflectance (≥90% at 700nm), resolving the technical contradiction between conversion efficiency and reliability.
2Productivity
If the Si/Al atomic ratio is increased to improve conversion efficiency, then blue light absorption enhances, but the crystal structure stability may deteriorate
Solution Approach 1:
The patent resolves this contradiction through controlled parameter changes by defining an optimal Si/Al atomic ratio range of 1.2 to 6.0 within the phosphor composition Mx(Si, Al)2(N, O)3±y. This controlled variation in the Si/Al ratio enables optimization of blue light absorption and conversion efficiency while maintaining crystal structure stability. The patent further refines this by specifying preferred sub-ranges (1.5-4.0 for high efficiency applications) and combining it with controlled O/N ratios (0.0-0.15) to stabilize the crystal structure across the composition range.
3Loss of energy
If the O/N atomic ratio is optimized to enhance internal quantum efficiency, then fluorescence intensity increases, but the manufacturing precision requirements increase
Solution Approach 1:
The patent addresses this contradiction through systematic parameter changes and expansions. It defines the O/N atomic ratio within a relatively wide range of 0.0 to 0.15, which provides manufacturing flexibility while still achieving high internal quantum efficiency (≥85%). The patent further expands the compositional flexibility by defining x in the range of 0.5-1.5 and y in the range of 0.01-0.3, allowing manufacturers to adjust other parameters to compensate for variations in O/N ratio control, thus maintaining performance while reducing manufacturing precision requirements.
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 powder achieves high internal quantum efficiency and excellent blue light conversion efficiency, maintaining fluorescence properties and heat resistance, making it suitable for wide-range light-emitting devices.
Implementation Method 1
a phosphor is used as a wavelength conversion material for obtaining white light from blue light emitted from a blue LED
Implementation Method 2
a diffuse reflectance X1 with respect to light having a wavelength of 700 nm is equal to or more than 88% and equal to or less than 99.9%
Data Source
AI summary
A phosphor powder which is represented by a general formula Mx(Si, Al)2(N, O)3±y (where M is Li and one or more alkaline earth metal elements and 0.52≤x≤0.9 and 0.06≤y≤0.36 are satisfied) and in which a part of M is substituted with a Ce element, in which the phosphor powder includes phosphor particles in which a Si/Al atomic ratio is equal to or more than 1.5 and equal to or less than 6, an O/N atomic ratio is equal to or more than 0 and equal to or less than 0.1, 5 to 50 mol % of M is Li, and 0.5 to 10 mol % of M is Ce, and a diffuse reflectance X1 with respect to light having a wavelength of 700 nm is equal to or more than 88% and equal to or less than 99.9%.