PC Red LED Phosphor Blend to Eliminate Blue Pass Through
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Solution Overview
Problem
Current PC Red LEDs face challenges in generating narrowband red light due to the high cost and low absorption efficiency of narrowband red fluoride phosphors, which also suffer from moisture sensitivity and 'blue pass through' issues.
Innovation Solution
Incorporating a combination of narrowband red fluoride phosphors and broadband red phosphors in PC Red LEDs, where the broadband red phosphor with higher absorption efficiency compensates for the lower absorption of the narrowband phosphor, reducing 'blue pass through' and improving color purity. This can be achieved in either a single-layer or double-layer photoluminescence structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If narrowband red fluoride phosphors are used to generate narrowband red light, then color purity is improved, but absorption efficiency deteriorates and cost increases
Solution Approach 1:
The patent combines narrowband red fluoride phosphor particles with broadband red phosphor particles in a single photoluminescence layer. The broadband red phosphor has higher absorption efficiency for blue excitation light, compensating for the low absorption efficiency of the narrowband red fluoride phosphor, while the narrowband component maintains high color purity in the emitted red light.
Solution Approach 2:
The invention uses a composite photoluminescence material system consisting of two types of red phosphors with complementary properties. The narrowband red fluoride phosphor (e.g., K2SiF6:Mn4+) provides narrow emission bandwidth for high color purity, while the broadband red phosphor (e.g., CaAlSiN3:Eu2+) provides high absorption efficiency, creating a synergistic composite material that overcomes the limitations of individual phosphors.
2Manufacturing precision
If narrowband red fluoride phosphors are used, then color purity is improved, but cost increases
Solution Approach 1:
The patent combines narrowband red fluoride phosphor particles with broadband red phosphor particles in a single photoluminescence layer. The broadband red phosphor has higher absorption efficiency for blue excitation light, compensating for the low absorption efficiency of the narrowband red fluoride phosphor, while the narrowband component maintains high color purity in the emitted red light.
Solution Approach 2:
The invention uses a small amount of expensive narrowband red fluoride phosphor combined with a larger amount of cheaper broadband red phosphor. This approach reduces the overall cost by minimizing the quantity of expensive narrowband phosphor required while maintaining high color purity through the narrowband component's emission characteristics.
3Manufacturing precision
If narrowband red fluoride phosphors are used, then color purity is improved, but reliability deteriorates due to moisture sensitivity
Solution Approach 1:
The broadband red phosphor acts as an intermediary protective layer that absorbs blue excitation light before it can reach and potentially degrade the moisture-sensitive narrowband red fluoride phosphor. Additionally, the broadband phosphor layer provides a physical barrier that reduces direct exposure of the narrowband phosphor to moisture and oxygen in the environment.
Solution Approach 2:
The patent incorporates the broadband red phosphor in advance to provide protective cushioning against moisture and oxygen degradation. The broadband phosphor layer is positioned to shield the narrowband red fluoride phosphor from environmental damage before degradation can occur, extending the operational lifetime and reliability of the PC Red LED.
4Manufacturing precision
If narrowband red fluoride phosphors are used, then color purity is improved, but blue pass through increases
Solution Approach 1:
The patent combines narrowband red fluoride phosphor particles with broadband red phosphor particles in a single photoluminescence layer. The broadband red phosphor has higher absorption efficiency for blue excitation light, compensating for the low absorption efficiency of the narrowband red fluoride phosphor, while the narrowband component maintains high color purity in the emitted red light.
Solution Approach 2:
The invention uses a composite photoluminescence material system consisting of two types of red phosphors with complementary properties. The narrowband red fluoride phosphor (e.g., K2SiF6:Mn4+) provides narrow emission bandwidth for high color purity, while the broadband red phosphor (e.g., CaAlSiN3:Eu2+) provides high absorption efficiency, creating a synergistic composite material that overcomes the limitations of individual phosphors.
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 proposed solution significantly reduces the usage and cost of narrowband red fluoride phosphors, enhances the absorption efficiency, and eliminates 'blue pass through', resulting in improved color purity and luminous efficacy of the red light emitted by PC Red LEDs.
Implementation Method 1
a photoluminescence material, wherein the photoluminescence material comprises a narrowband red fluoride phosphor and a broadband red phosphor
Data Source
AI summary
A red-light emitting device comprising: a blue LED chip; and a photoluminescence material comprising a narrowband red fluoride phosphor and a broadband red phosphor. The narrowband red phosphor may comprise a manganese-activated fluoride phosphor of composition K2SiF6:Mn4+, K2GeF6:Mn4+, and K2TiF6:Mn4+.