Ce-activated CaAlSiN3 Orange Phosphor for White LED Color Rendering
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Solution Overview
Problem
Existing light-emitting devices using a combination of blue LEDs and Ce-activated YAG fluorescent materials suffer from low light emitting efficiency and inadequate color rendering indices, particularly in the red spectrum, leading to unnatural skin tone representation and poor color fidelity.
Innovation Solution
Incorporating a Ce-activated CaAlSiN3 fluorescent material in a solid solution crystal form, with a composition of cCaAlSiN3.(1−c)LiSi2N3 where 0.2≦c≦0.8, and containing 2 weight % or more of Ce, along with a green fluorescent material, to enhance the emission spectrum and improve color rendering indices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a Ce-activated YAG fluorescent material is used with a blue LED, then light emitting efficiency is improved, but color rendering index (especially red component) deteriorates
Solution Approach 1:
The patent uses a composite fluorescent material system consisting of Ce-activated YAG (yellow emission) combined with red fluorescent materials (such as CaAlSiN3:Eu or Sr2Si5N8:Eu). This composite approach allows the yellow and red emissions to combine, improving both the color rendering index (especially R9 for red) while maintaining high light emitting efficiency through efficient blue LED excitation of both fluorescent components
2Manufacturing precision
If a red fluorescent material is added to improve color rendering index, then color rendering index is improved, but light emitting efficiency deteriorates
Solution Approach 1:
The patent optimizes the emission peak wavelength of the red fluorescent material to be in the range of 600-680 nm (preferably 610-650 nm), and controls the weight ratio of red to yellow fluorescent material between 1:9 and 4:6. These parameter optimizations ensure that the red fluorescent material contributes to color rendering while minimizing negative impact on overall light emitting efficiency by selecting materials with high quantum efficiency and appropriate spectral overlap with the blue LED emission
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 solution results in a light-emitting device that emits white light with high luminous efficiency and excellent color rendering indices, effectively addressing the limitations of previous technologies by broadening the emission spectrum and improving the representation of red tones.
Implementation Method 1
an orange fluorescent material which absorbs the blue light so as to emit orange light
Implementation Method 2
a green fluorescent material which absorbs the blue light so as to emit green light
Implementation Method 3
a light-emitting element for emitting blue light
Data Source
AI summary
There is realized a light-emitting device that emits, with high efficiency, white light with excellent color rendering index. A light-emitting device (1) of the present invention is a light-emitting device (1) for emitting white light, including at least a light-emitting element (2) for emitting blue light, an orange fluorescent material (13) which absorbs the blue light so as to emit orange light, and a green fluorescent material (14) which absorbs the blue light so as to emit green light, the orange fluorescent material (13) being a Ce-activated CaAlSiN3 fluorescent material in a solid solution crystal form in which Ce and oxygen are dissolved in a crystal having a composition of cCaAlSiN3.(1−c)LiSi2N3 where 0.2≦c≦0.8, and the orange fluorescent material (13) containing 2 weight % or more of Ce.