Orange-Emitting Phosphor for High Luminance LEDs
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Solution Overview
Problem
Current phosphors that emit red or orange light upon excitation by blue light lack stability and luminance, and existing orange-emitting phosphors are not sufficient in luminance, posing challenges for improved color rendering in light-emitting diodes.
Innovation Solution
An orange-emitting phosphor with the general formula a(Sr1-xEux(1-y)Ybxy)O.SiO2, where a is between 2.9 and 3.1, x is between 0.005 and 0.1, and y is between 0.001 and 0.1, is synthesized by mixing strontium, europium, and ytterbium compounds with silicon, and fired under specific conditions to achieve high luminance and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alkaline-earth metal sulfide phosphor by activation of divalent europium is used to emit red light, then color rendering properties are improved, but the phosphor easily undergoes chemical change and may produce harmful sulfur compounds
Solution Approach 1:
The patent replaces the harmful sulfide-based phosphor with an oxide-based phosphor that eliminates sulfur compound production while maintaining the desired red-orange light emission properties. The chemical composition Sr1-xEuxO:SiO2 provides a stable oxide structure that avoids the harmful byproducts of sulfide phosphors.
2Illumination intensity
If alkaline-earth metal silicate phosphor by activation of divalent europium is used to emit orange light, then color rendering properties are improved, but luminance is insufficient
Solution Approach 1:
The patent optimizes the compositional parameters of the phosphor, specifically the ratio of Sr to Eu (controlled by parameter x) and the SiO2 content (controlled by parameter a), to simultaneously achieve high luminance and excellent color rendering properties. The specific ranges 2.9≦a≦3.1 and 0.005≦x≦0.1 are determined to provide the optimal balance between brightness and color quality.
3Illumination intensity
If a phosphor with high luminance is used in LED, then illumination intensity is improved, but the phosphor may be unstable and produce harmful compounds
Solution Approach 1:
The patent creates a composite phosphor material combining Sr1-xEuxO with SiO2 to form a stable oxide-based composite that maintains high luminance while preventing chemical degradation and harmful gas production. The SiO2 component provides structural stability and prevents the degradation issues seen in pure sulfide phosphors.
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 resulting phosphor exhibits high luminance and improved color rendering properties when combined with semiconductor light-emitting elements, offering a stable and efficient orange light emission without harmful gas production.
Implementation Method 1
a phosphor serving as a converting material absorbs visible light in the blue region emitted by a GaN-based blue light-emitting diode to emit yellow light
Data Source
AI summary
An orange-emitting phosphor that emits at a high luminance when being excited by blue light emitted by a blue light-emitting diode is provided. This orange-emitting phosphor is an alkaline-earth metal silicate-based phosphor represented by a general formula of a(Sr1-xEux(1-y)Ybxy)O.SiO2. In the formula, a is provided as 2.9≦a≦3.1, x is provided as 0.005≦x≦0.10, and y is provided as 0.001≦y≦0.1. An orange-emitting phosphor that emits orange at a high luminance and produces no harmful gas is provided.