Nitrido Orthosilicate Phosphor Stability and Efficiency
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Solution Overview
Problem
Stable green phosphors with optimal emission characteristics are scarce, limiting the use of conversion LEDs in display backlighting and high-CRI/warm white LEDs, and existing nitrido orthosilicates face stability issues in humid environments and high temperatures.
Innovation Solution
Development of novel nitrido orthosilicate phosphors with a SiO2 deficit, specifically designed for blue to yellow emission, using a composition of EA2-x-aSE x Eu a Si1-y O 4-x-2y N x (EA = Sr, Ba, Ca, Mg; SE = rare earths) to enhance stability and quantum efficiency, suitable for LEDs and white OLEDs, with excitation in the UV and blue range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional orthosilicates are used as green phosphors, then high quantum efficiency can be achieved, but inadequate aging behavior and poor stability in humid environments and at high temperatures occur
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the orthosilicate phosphor. Specifically, it introduces a controlled SiO2 deficit (substoichiometric composition where y > 0) and incorporates nitrogen to create nitrido orthosilicates with the formula EA2-x-aSE x Eu a Si1-yO 4-x-2y N x. This compositional parameter change transforms the material properties, achieving both high quantum efficiency and improved stability against aging, humidity, and temperature.
Solution Approach 2:
The patent creates composite materials by combining multiple elements and compounds within the phosphor structure. The nitrido orthosilicate comprises alkaline earth elements (EA), rare earth elements (SE), europium (Eu), silicon, oxygen, and nitrogen in a specific composite structure. This composite approach, particularly the integration of nitrogen into the orthosilicate lattice, produces a material that simultaneously achieves high quantum efficiency and enhanced environmental stability.
2Adaptability or versatility
If stable green phosphors with optimal emission characteristics are used, then conversion LEDs can be optimized for display backlighting and high-CRI LEDs, but such phosphors are hardly available
Solution Approach 1:
The patent achieves adaptability for multiple applications by precisely controlling compositional parameters. The formula EA2-x-aSE x Eu a Si1-yO 4-x-2y N x allows tuning of emission characteristics through variation of x, a, and y parameters while maintaining the beneficial SiO2 deficit structure. This parameter optimization enables the phosphor to meet the specific requirements of display backlighting and high-CRI LED applications.
Solution Approach 2:
The nitrido orthosilicate phosphor developed in the patent achieves universality by being suitable for multiple applications simultaneously. The same phosphor composition can be used in conversion LEDs for display backlighting, high-CRI LEDs, and warm white LEDs, replacing the need for different specialized phosphors for each application.
3Use of energy by moving object
If nitrido orthosilicates with YN and/or LaN incorporation are used, then red shift in spectral position and improved quantum efficiency are achieved, but stability in humid environments and at higher temperatures is still not optimal
Solution Approach 1:
The patent applies parameter changes by introducing a controlled SiO2 deficit (where y > 0 in the formula Si1-y) in addition to the YN/LaN incorporation. This dual parameter modification - combining rare earth nitride incorporation with substoichiometric silicon content - creates a more stable crystal structure that resists degradation from humidity and temperature while maintaining high quantum efficiency and achieving the desired spectral red shift.
Solution Approach 2:
The patent creates a composite material structure that combines YN/LaN with a SiO2-deficit nitrido orthosilicate matrix. This composite approach, represented by the formula EA2-x-aSE x Eu a Si1-yO 4-x-2y N x, produces synergistic effects where the nitrogen incorporation and silicon deficit work together to enhance both optical performance and environmental stability.
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 novel phosphors demonstrate improved stability and quantum efficiency, particularly in humid environments and high temperatures, enabling their use in high-CRI LEDs and white LEDs with enhanced color rendering and energy efficiency.
Implementation Method 1
The phosphors can be used in particular in LEDs with good color rendering, in LEDs for LCD backlighting, color-on-demand LEDs or white OLEDs. The excitation of such phosphors is preferably done with short-wave radiation in the UV and short-wave blue, in particular in the range 360 to 480 nm.
Implementation Method 2
a conversion LED is known which uses a modified regular orthosilicate as a phosphor
Data Source
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AI summary
The invention relates to a novel luminescent substance from the class of orthosilicates, comprising a sub-stoichiometric fraction of Si. SE and N are added in particular for stabilizing.