Yellow Phosphor Composition for LED Lighting Spectral Efficacy
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Solution Overview
Problem
The YAG:Ce-based phosphor used in LED lighting has a wide yellow light emission peak that deviates from the spectral luminous efficacy curve, resulting in low brightness and color purity, and the La4−αCaαSi12O3+αN18−α:Eu phosphor suffers from incidental crystal phase generation during composition, affecting crystallizability and light emission intensity.
Innovation Solution
A yellow phosphor with a composition represented by the formula Ln4−x(EuzM1−z)xSi12−yAlyO3+x+yN18−x−y, where Ln includes rare earth elements and M includes calcium, barium, or strontium, with a monoclinic crystal structure and specific mole ratios, is developed to enhance spectral luminous efficacy, color purity, and light emission intensity without inducing incidental phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If YAG:Ce-based phosphor is used, then quantum efficiency is improved, but spectral luminous efficacy efficiency deteriorates due to wide emission peak deviation from 555 nm
Solution Approach 1:
The patent changes the chemical composition parameters by replacing Y with Ln (rare earth elements) and adjusting the Si-Al-O-N ratio to achieve a narrower emission peak centered near 555 nm, thereby improving spectral luminous efficacy while maintaining quantum efficiency through optimized crystal structure
2Illumination intensity
If La4−αCaαSi12O3+αN18−α:Eu phosphor is used, then spectral luminous efficacy efficiency is improved with narrow emission peak, but crystallizability deteriorates due to incidental crystal phase generation
Solution Approach 1:
The patent modifies the composition parameters by introducing M elements (Ca, Sr, Ba, Mg) and adjusting the Si-Al ratio, along with optimizing sintering conditions, to suppress incidental phase formation and improve crystallizability while preserving the narrow emission peak characteristics
Solution Approach 2:
The patent creates a composite phosphor system combining Ln-Si-Al-O-N base structure with M element dopants, forming a multi-element composite that achieves both high spectral luminous efficacy and improved crystallizability through synergistic effects of different elements
3Adaptability or versatility
If yellow phosphor with wide emission peak is used, then color coverage is improved, but color purity deteriorates
Solution Approach 1:
The patent optimizes the emission peak wavelength parameter to be centered at 555 nm with controlled full width at half maximum (FWHM), achieving a balance where the phosphor maintains adequate color coverage while delivering high color purity through the narrow, well-positioned emission peak
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 improved spectral luminous efficacy, high color purity, and increased light emission intensity while maintaining stability during composition, outperforming conventional YAG:Ce-based phosphors and La4−αCaαSi12O3+αN18−α:Eu phosphors.
Implementation Method 1
The yellow phosphor emits yellow light by using light emitted from the LED as an excitation source
Data Source
AI summary
A yellow phosphor is provided. The yellow phosphor includes a crystal formed of a compound that is represented by the following formula (1): Ln4−x(EuzM1−z)xSi12−yAlyO3+x+yN18−x−y(0.5≦x≦3, 0<z<0.3, 0<y≦4) (1), wherein Ln includes at least one rare earth element, and M includes at least one selected from calcium (Ca), barium (Ba), strontium (Sr), and magnesium (Mg).