Core-Shell Red Phosphor for High Luminous Efficiency and Water Resistance
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Solution Overview
Problem
Current red phosphors for wide-color-gamut liquid crystal display LED backlights either have poor luminous efficiency and temperature tolerance or inadequate water resistance, limiting the development of this technology.
Innovation Solution
A red phosphor with a germanium fluoride inner core and a silicon-containing fluoride outer shell, optimized by specific molar ratios and particle sizes, providing enhanced luminous efficiency, temperature tolerance, and water resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional silicon fluoride phosphor (KSiF6:Mn4+) is used, then water resistance is improved, but luminous efficiency and temperature tolerance deteriorate
Solution Approach 1:
The patent applies composite materials by creating a core-shell structured phosphor where the core is made of germanium fluoride (KGeF6:Mn4+) providing high luminous efficiency and temperature tolerance, while the shell is made of silicon fluoride (KSiF6) providing water resistance. This composite structure allows the phosphor to simultaneously achieve high luminous efficiency (94% of initial value after 1000h at 85℃) and excellent water resistance, resolving the contradiction between these two properties in conventional single-material phosphors.
2Productivity
If germanium fluoride phosphor (KGeF6:Mn4+) is used, then luminous efficiency and temperature tolerance are improved, but water resistance deteriorates
Solution Approach 1:
The patent uses composite materials to combine the advantages of different phosphor materials. The germanium fluoride core provides superior luminous efficiency and temperature tolerance, while the silicon fluoride shell provides water resistance. This composite approach allows the phosphor to achieve luminous efficiency of 94% retention after 1000 hours at 85℃ and excellent water resistance, simultaneously resolving the contradiction between luminous efficiency and water resistance.
Solution Approach 2:
The patent employs a thin film shell structure where a silicon fluoride layer (0.5-15 μm thickness) coats the germanium fluoride core. This flexible shell configuration protects the core material from water degradation while maintaining the core's high luminous efficiency properties, effectively resolving the water resistance issue of germanium fluoride phosphor.
3Illumination intensity
If phosphor particle size is increased, then luminous flux output is improved, but color uniformity and manufacturing precision deteriorate
Solution Approach 1:
The patent optimizes the particle size parameter to 15-35 μm, which balances luminous flux output with color uniformity and manufacturing precision. This specific parameter range allows sufficient light output while maintaining narrow FWHM (45-55 nm) for accurate color rendering and facilitating consistent manufacturing through controlled synthesis processes.
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 phosphor achieves improved luminous efficiency, temperature stability, and water resistance, enabling high-performance wide-color-gamut displays with reduced luminous flux decay and enhanced weather fastness.
Implementation Method 1
a blue-light LED chip+ phosphor to produce pure red, blue and green light after filtering and splitting
Data Source
AI summary
The present invention relates to a red phosphor, a preparation method thereof and a light-emitting device prepared therefrom. A particle of the red phosphor consists of a phosphor inner core having a chemical formula of Ax1Gez1F6:y1Mn4+ and an outer shell having a chemical formula of Bx2Mz2F6:y2Mn4+, wherein 1.596≤x1≤2.2, 1.6≤x2≤2.2, 0.001≤y1≤0.2, 0≤y2≤0.2, 0.9≤z1≤1.1, and 0.9≤z2≤1.1; A and B are independently selected from alkali metal elements; and M is Si, or Si and Ge. The red phosphor provided by the present invention has high luminous efficiency and stability. Moreover, the phosphor alone or in combination with other luminescent materials can be used for preparing a light-emitting device with high performance.