Alkaline Earth Ortho-Silicate Fluorescent Substance for White LEDs
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Solution Overview
Problem
The existing silicate fluorescent substances used in white LEDs, such as YAG and Sr2SiO4:Eu2+, face limitations in luminescence efficiency and toxicity due to their crystal structure and the use of Ba, which is toxic and requires minimal content to avoid regulatory restrictions.
Innovation Solution
A fluorescent substance comprising an alkaline earth ortho-silicate activated by Eu2+, with La, Gd, Cs, or K, which changes the crystal structure from monoclinic to orthorhombic, allowing for high color purity yellow luminescence with minimal Ba content, and is synthesized using specific compositional ratios and processing methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Ba compound is used to obtain high color purity yellow luminescence, then color purity is improved, but toxicity increases and regulatory restrictions apply
Solution Approach 1:
The invention changes the chemical composition parameters by replacing toxic Ba with non-toxic La, Gd, Cs, or K elements in the silicate fluorescent substance formula (M2SiO4:Eu), maintaining the orthorhombic crystal structure and yellow luminescence properties while eliminating toxicity concerns
Solution Approach 2:
The invention uses abundant, non-toxic earth elements (La, Gd, Cs, K) as substitutes for rare and toxic Ba, creating a safer fluorescent material that can be freely applied without regulatory restrictions
2Ease of manufacture
If YAG fluorescent substance is used, then manufacturing is simple, but luminescence efficiency is weak when excited with 360-410 nm light
Solution Approach 1:
The invention changes the crystal structure parameter from monoclinic to orthorhombic system by using specific alkaline earth elements (La, Gd, Cs, K) combined with Eu2+ activation, which dramatically improves luminescence efficiency under 360-410 nm excitation while maintaining ease of manufacture
3Ease of manufacture
If Sr2SiO4:Eu2+ with monoclinic structure is used, then manufacturing is easier, but color purity is lower compared to orthorhombic structure
Solution Approach 1:
The invention changes the crystal structure parameter from monoclinic to orthorhombic system by selecting specific alkaline earth elements (La, Gd, Cs, K) for the M2SiO4 formula, achieving high color purity yellow luminescence with peak wavelength of 570 nm while keeping the manufacturing process straightforward
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 achieves high color purity yellow luminescence with a single emission band between 520-600 nm, overcoming toxicity issues and maintaining emission efficiency, and can be used in white LEDs with improved reliability and safety.
Implementation Method 1
A fluorescent substance comprises an alkaline earth ortho-silicate, the fluorescent substance being activated by Eu2+
Implementation Method 2
the luminescence thereof would become yellow of high color purity having a peak wavelength of 570 nm
Data Source
AI summary
Disclosed is a fluorescent substance comprising an alkaline earth ortho-silicate, the fluorescent substance being activated by Eu2+, and further comprising at least one selected from the group consisting of La, Gd, Cs and K.