Nitridoberyllosilicate Phosphor Composition for Stable Narrow-Band Green LEDs
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Solution Overview
Problem
Existing phosphors used in phosphor-converted LEDs (pcLEDs) face issues such as low blue light absorption, concentration quenching, and reliability problems, particularly with Eu-doped beta-SiAlON and SrSi2O2N2:Eu, which have limited photothermal stability and emission in the dark green spectral range.
Innovation Solution
Development of nitridosilicate phosphors with a formula AE1-x-y-uA y+uBe1-y-z-vB y+z+vSi1-zAlzO1-vN2+v:Eux,Ceu, which exhibit improved chemical stability, photostability, and narrow band green light emission, characterized by a full width at half maximum (FWHM) of less than 55 nm, achieved through doping with B, Al, and monovalent alkaline atoms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Eu concentration is increased to improve green light emission intensity, then emission intensity improves, but concentration quenching occurs reducing reliability
Solution Approach 1:
The patent changes the chemical composition parameters of the host lattice by incorporating B, Al, and monovalent alkaline atoms in specific ratios. This modifies the crystal field environment around Eu ions, allowing higher Eu concentrations to be incorporated without concentration quenching, thus resolving the contradiction between emission intensity and reliability
Solution Approach 2:
The patent creates a composite phosphor material with multiple elements (B, Al, monovalent alkaline atoms, Eu) combined in a specific formula. This composite structure provides both the necessary green emission intensity and improved stability against concentration quenching, simultaneously achieving high intensity and reliability
2Use of energy by moving object
If phosphor layer thickness is increased to improve light absorption, then absorption efficiency improves, but emission intensity deteriorates due to reabsorption and quenching
Solution Approach 1:
The patent modifies the optical properties of the phosphor material by changing its chemical composition. The incorporated B, Al, and monovalent alkaline atoms alter the absorption and emission characteristics, improving blue light absorption while maintaining high green emission intensity even at optimal thicknesses, thus resolving the contradiction between absorption efficiency and emission intensity
3Illumination intensity
If conventional phosphors are used to achieve green emission, then green light output is obtained, but photothermal stability and reliability are insufficient
Solution Approach 1:
The patent develops a composite phosphor material with a specific multi-element composition including B, Al, monovalent alkaline atoms, and Eu. This composite structure provides both the required green light output and significantly improved photothermal stability and reliability compared to conventional single-element phosphors
4Manufacturing precision
If narrow band green phosphors are used to improve color gamut, then color rendering improves, but blue light absorption and reliability are insufficient
Solution Approach 1:
The patent optimizes the chemical composition parameters of the phosphor material to achieve a balance between narrow emission band (for color gamut) and strong blue light absorption (for reliability). The specific incorporation of B, Al, and monovalent alkaline atoms creates a material that simultaneously achieves both requirements
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 nitridosilicate phosphors provide enhanced blue light absorption and improved photostability, enabling the production of narrow band green light with better reliability and color rendering properties, suitable for displays and adaptive illumination systems.
Implementation Method 1
nitridosilicate phosphors with a formula AE1-x-y-uA y+uBe1-y-z-vB y+z+vSi1-zAlzO1-vN2+v:Eux,Ceu, which exhibit improved chemical stability, photostability, and narrow band green light emission
Implementation Method 2
the fraction of the light emitted by the LED that is absorbed by the phosphors depends on the amount of phosphor material in the optical path of the light emitted by the LED
Data Source
Figure 1~2B
Figure 3A~3B
Figure 4A~4B
AI summary
A family of optionally substituted oxonitridoberyllosilicate photoluminescent compositions (i.e., phosphors) is characterized by the formula AE1-x-y-uAy+uBe1-y-z-vBy+z+vSi1-zAlzO1-vN2+v:Eux,Ceu, where AE = Ba, Sr, Ca, Mg; A = Li, Na, K, Rb; 0 ≤ x ≤ 0.1; 0 ≤ u ≤ 0.1; 0 < (x + u); 0 ≤ y ≤ 1; 0 ≤ z ≤ 1; (y + z + v) ≤ 1; and (x + y + u) ≤ 1. These phosphors may be used in phosphor converted LEDs which may be advantageously employed in illumination and display applications, for example.