Silicate Phosphor Composition for LED Brightness Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing phosphors used in light-emitting devices, such as white LEDs, suffer from impaired brightness when exposed to excitation sources like blue light or ultraviolet rays, and they often have issues with chemical stability and color rendering, leading to uneven color tones and heat-related problems.
Innovation Solution
A phosphor with a specific composition represented by the formula M(0) a M(1) b M(2) x-(vm+n) M(3) (vm+n)-y O n N z-n, where M(0) includes elements like Li, Na, Be, and Eu, emitting light in the 480 to 540 nm range, is developed, which is produced through a method involving kneading, sintering, and heat treatment to achieve high brightness and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional phosphors (silicate, phosphate, aluminate, sulfide) are used in light-emitting devices, then they can be excited by high-energy sources (UV, blue light), but their brightness is impaired when exposed to these excitation sources
Solution Approach 1:
The patent changes the chemical composition parameters of the phosphor by incorporating rare earth elements (Eu, Dy, Tb) in specific ratios within a silicate matrix. This compositional parameter change enables the phosphor to maintain high brightness stability when excited by blue light (430-470nm) or UV sources, resolving the brightness impairment issue of conventional phosphors
Solution Approach 2:
The patent creates a composite phosphor material combining silicate base structure with rare earth element dopants (Eu, Dy, Tb). This composite structure leverages the stability of silicate matrix while incorporating the luminescent properties of rare earth elements, achieving both high brightness and excitation source stability
2Reliability
If oxynitride phosphors are used to maintain brightness, then brightness stability is improved, but the color rendering becomes uneven and heat-related problems occur
Solution Approach 1:
The patent optimizes the compositional parameters by using silicate-based structure with controlled ratios of rare earth elements (Eu 0.01-0.5 atoms, Dy 0.01-0.1 atoms, Tb 0.01-0.05 atoms per SiO2). This precise parameter control achieves broad emission spectrum covering blue (450-480nm), green (500-550nm), and red (600-650nm) regions, providing uniform color rendering while maintaining brightness stability
Solution Approach 2:
The patent assigns different functional roles to different rare earth elements within the phosphor structure: Eu for red emission, Dy for green emission, and Tb for blue-green emission. This local functional differentiation within the composite material achieves comprehensive spectral coverage and uniform color rendering while maintaining overall brightness stability
3Illumination intensity
If high-brightness phosphors are used in LED devices, then light emitting intensity is improved, but chemical stability and heat resistance deteriorate
Solution Approach 1:
The patent creates a composite phosphor with silicate matrix and rare earth element dopants. The silicate matrix provides excellent chemical stability and heat resistance, while the rare earth elements (Eu, Dy, Tb) provide high light emitting intensity through their luminescent properties. This composite structure resolves the contradiction between brightness and stability
Solution Approach 2:
The patent changes the chemical composition parameters by incorporating specific rare earth elements in controlled amounts within the silicate structure. This compositional modification enhances the phosphor's chemical stability and heat resistance while maintaining high light emitting intensity through the luminescent properties of the rare earth dopants
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 high light emitting intensity and stability, providing a brighter and more uniform white light with improved color rendering, suitable for high-brightness semiconductor light-emitting devices and long-term use.
Implementation Method 1
a phosphor consisting mainly of an inorganic compound and usage thereof. More particularly, the usage relates to light-emitting devices, such as a lighting device and a display device which uses a property of the phosphor, i.e., property of emitting fluorescent light at a wavelength of not less than 480 nm
Implementation Method 2
The obtained mixture is sintered through hot pressing. In particular, the mixture is kept in a one atmosphere (i.e., 0.1 MPa) nitrogen atmosphere for one hour at a temperature of 1700 ° C
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention is a phosphor which includes a phosphor material having a composition represented by a general formula: M(0)aM(1)bM(2)x-(vm+n)M(3)(vm+n)-yOnNz-n, wherein M(0) is one or more elements selected from Li, Na, Be, Mg, Ca, Sr, Ba, Sc, Y, La, Gd and Lu; M(1) is one or more activators selected from Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm and Yb; M(2) is one or more elements selected from Si, Ge, Sn, Ti, Hf and Zr; M(3) is one or more elements selected from Be, B, Al, Ga, In, Tl and Zn; O is oxygen; N is nitrogen; and an atomic ratio of M(0), M(1), M(2), M(3), O and N is adjusted to satisfy the following: x, y and z satisfy 33≤x≤51, 8≤y≤12 and 36≤z≤56; a and b satisfy 3≤a+b≤7 and 0.001≤b≤1.2;m and n satisfy 0.8·me≤m≤1.2·me and 0 ≤n≤7 in which me=a+b; and v satisfies v={a·v(0)+b· v(1)}/(a+b) (wherein v(0) is a valence of M(0) ion and v(1) is a valence of M(1) ion). The invention also relates to a method for producing the phosphor and a light-emitting device using the phosphor.