Red Nitride Phosphor Composition for Narrow-Band LED Emission
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Solution Overview
Problem
Current phosphors used in light-emitting devices have unclear emission intensity and conversion efficiency, with a need for improved color rendering and reproducibility, particularly in vehicle illumination and display devices.
Innovation Solution
A light-emitting device comprising a phosphor with a specific crystal phase composition, where the intensity ratio of certain peaks in the powder X-ray diffraction spectrum is controlled to enhance emission efficiency and color rendering, utilizing a composition represented by formulas RexMAaMBbMCcNdXe and RexMAaMBb(MC′1-yMDy)cNdXe, with specific elemental ratios and space group P−1, to achieve a narrow full width at half maximum and optimal emission wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional red phosphors (KSF, S/CASN) are used, then red light emission is achieved, but emission intensity is insufficient and conversion efficiency is low
Solution Approach 1:
The patent changes the crystal structure parameters by controlling the Ix/Iy ratio in the XRD spectrum to be 0.140 or less, which corresponds to specific compositional ranges in the SrLiAl3N4:Eu phosphor system. This parameter change optimizes the crystal phase composition to achieve both high emission intensity and high conversion efficiency, resolving the contradiction between these two performance metrics.
2Illumination intensity
If phosphors with broad FWHM (80-90 nm) are used, then red light emission is achieved, but the emission wavelength region includes wavelengths with low relative luminous efficiency
Solution Approach 1:
The patent achieves narrow FWHM (60-80 nm) by precisely controlling the compositional parameters within the SrLiAl3N4:Eu system and optimizing the sintering conditions. This parameter optimization narrows the emission spectrum to concentrate luminous energy in the high-efficiency wavelength region (610-680 nm), improving relative luminous efficiency while maintaining manufacturability through defined compositional ranges.
3Object-affected harmful factors
If Mn-activated KSF phosphor is used, then red light emission is achieved, but the phosphor is harmful to humans and the environment
Solution Approach 1:
The patent replaces the harmful Mn-activated KSF phosphor with a Eu-activated SrLiAl3N4 phosphor system. This substitution eliminates the harmful effects of Mn activation while achieving superior emission intensity and conversion efficiency. The Eu-doped nitride phosphor provides the same red light emission function without the environmental and health hazards, effectively converting a harmful solution into a beneficial one.
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 provides light-emitting devices with improved color rendering, color reproducibility, and conversion efficiency, achieving superior emission characteristics and luminous efficacy.
Implementation Method 1
An LED using, on a blue LED chip, a nitride phosphor that emits red light and a phosphor that emits green light, with blue light from the blue LED chip as excitation light
Data Source
AI summary
A phosphor having a favorable emission peak wavelength, narrow full width at half maximum, and/or high emission intensity is provided. Additionally, a light-emitting device, an illumination device, an image display device, and/or an indicator lamp for a vehicle having favorable color rendering, color reproducibility and/or favorable conversion efficiency are provided. The present invention relates to a phosphor including a crystal phase having a composition represented by a specific formula, and when, in a powder X-ray diffraction spectrum of the phosphor, the intensity of a peak that appears in a region where 2θ=38-39° is designated as Ix and the intensity of a peak that appears in a region where 2θ=37-38° is designated as Iy, the relative intensity Ix/Iy of Ix to Iy is 0.140 or less, and a light-emitting device comprising the phosphor.