Phosphor Powder Blue Light Conversion Efficiency
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Solution Overview
Problem
The phosphor disclosed in Patent Document 1 has room for improvement in terms of conversion efficiency of blue light, specifically in increasing internal quantum efficiency.
Innovation Solution
A phosphor powder with phosphor particles represented by the general 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, an O/N atomic ratio of 0 to 0.1, 5 to 50 mol % Li, and 0.5 to 10 mol % Ce, and a light absorption A700 at 700 nm of equal to or less than 10%, is developed. This phosphor powder is used in light-emitting devices, image display devices, and illumination devices.
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 light absorption at 700 nm increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the phosphor: Mx(Si, Al)2(N, O)3±y where 0.52≤x≤0.9 and 0.06≤y≤0.36, 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. By adjusting these compositional parameters within specific ranges, the patent achieves high internal quantum efficiency while maintaining light absorption at 700 nm at 10% or less.
2Loss of energy
If the Si/Al atomic ratio is increased to improve conversion efficiency, then blue light conversion improves, but manufacturing complexity increases
Solution Approach 1:
The patent defines a broad acceptable range for the Si/Al atomic ratio (1.5 to 6) that maintains high conversion efficiency. This parameter range provides manufacturing flexibility while ensuring performance requirements are met, reducing the complexity of precise control compared to narrower specifications.
3Loss of energy
If the O/N atomic ratio is optimized to improve internal quantum efficiency, then conversion efficiency increases, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies the O/N atomic ratio should be 0 to 0.1, providing a clear target range for manufacturing. This parameter specification balances the need for high internal quantum efficiency with practical manufacturability, as the range is narrow enough to ensure performance but broad enough to allow for normal manufacturing variations.
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 conversion efficiency of blue light, with improved 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 light absorption A700 at a wavelength of 700 nm is equal to or less than 10%
Data Source
AI summary
A phosphor powder including phosphor particles of a phosphor 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, 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. A light absorption A700 of this phosphor powder at a wavelength of 700 nm is equal to or less than 10%.