Fluoride Phosphor Ceramic Structure for Low-Quenching LED Lighting
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Solution Overview
Problem
Current phosphor-converted white light LEDs face limitations in achieving high efficiency, color rendering index, and long-term stability due to broad emission bandwidths of red phosphors, which lead to thermal quenching and environmental degradation, especially in high-flux applications.
Innovation Solution
The consolidation of K2SiF6:Mn4+ phosphor into a ceramic structure, combined with other phosphors like Ce-doped garnets, forms a multicomponent phosphor ceramic that reduces thermal quenching and enhances stability, allowing for efficient conversion of blue light to tunable white light with improved thermal conductivity and chemical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If commercial red phosphors (SBSN, (Sr,Ba)2Si5N8:Eu2+, SCASN) are used to achieve high CRI and R9, then color rendering is improved, but emission bandwidth becomes broad (>70 nm) extending into infrared region, reducing efficacy
Solution Approach 1:
The patent changes the emission wavelength parameter of the red phosphor from the conventional 650 nm range to a narrower 615-640 nm range, and controls the bandwidth to 40-60 nm. This parameter optimization ensures the emission peak is centered in the optimal red region for high CRI and R9, while preventing energy loss into the infrared region where human eye sensitivity is low.
Solution Approach 2:
The patent uses a composite phosphor material system combining specific host lattice structures (such as Sr2Si5N8, Ba2Si5N8, or SrAlSiN3) with Eu2+ activators, and optionally combines multiple phosphor materials (e.g., red phosphor with narrow bandwidth 615-640 nm, green phosphor, and yellow phosphor) to achieve both high color rendering and efficient energy utilization.
2Loss of energy
If K2SiF6:Mn4+ (KSF) phosphor is used to achieve narrow emission bandwidth and high quantum efficiency, then efficacy is improved, but thermal quenching increases at high flux packages, degrading performance
Solution Approach 1:
The patent optimizes the Mn4+ doping concentration parameter in the K2SiF6 host lattice to a specific range (0.01-5%, preferably 0.1-1%) to achieve the optimal balance between quantum efficiency and thermal stability. This parameter optimization allows the phosphor to maintain high emission efficiency while reducing thermal quenching effects at operational temperatures.
Solution Approach 2:
The patent employs a composite structure combining K2SiF6:Mn4+ phosphor particles with a transparent or translucent fluoride ceramic matrix (such as Li2SiF6, Na2SiF6, K2SiF6, or Li2GeF6). This composite structure provides both the high quantum efficiency of the phosphor and the thermal stability of the ceramic matrix, preventing thermal quenching while maintaining optical performance.
3Loss of energy
If fluoride phosphor powder is used to achieve high quantum efficiency, then luminous efficiency is improved, but environmental degradation occurs due to water reactivity with high surface area powder
Solution Approach 1:
The patent creates a composite material where fluoride phosphor particles are embedded in a fluoride ceramic matrix. This composite structure maintains the high quantum efficiency of the phosphor particles while the ceramic matrix provides chemical stability and protects against water reactivity, eliminating the environmental degradation issue associated with high surface area powders.
Solution Approach 2:
The patent uses a fluoride ceramic matrix as a protective shell or surrounding medium that encapsulates the fluoride phosphor particles. This matrix structure physically isolates the phosphor from moisture and oxygen, preventing water reactivity and chemical degradation while allowing the phosphor to maintain its high quantum efficiency.
4Ease of manufacture
If phosphor powder in polymer composite is used to simplify manufacturing, then ease of manufacture is improved, but thermal conductivity is poor, leading to increased thermal quenching
Solution Approach 1:
The patent replaces the polymer composite matrix with a fluoride ceramic matrix, creating a new composite material system. This ceramic composite maintains manufacturing feasibility while providing superior thermal conductivity that prevents thermal quenching, resolving the contradiction between ease of manufacture and thermal performance.
Solution Approach 2:
The patent changes the thermal conductivity parameter of the composite material by replacing polymer with fluoride ceramic matrix. This parameter change increases the thermal conductivity from the poor thermal conductivity of polymer-composite to the superior thermal conductivity of fluoride ceramic-composite, thereby reducing thermal quenching while maintaining manufacturability.
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 ceramic structure achieves high color rendering index, reduced thermal quenching, and extended lifespan by minimizing infrared emission and environmental degradation, enabling efficient and durable LED lighting solutions.
Implementation Method 1
a fluoride phosphor matrix, being consolidated into a phosphor ceramic structure... The phosphor ceramic structure generates at least one of red or orange light when irradiated by the light emitted from the LED
Implementation Method 2
The phosphor ceramic structure exhibits reduced thermal quenching relative to a fluoride particulate or powder/polymer composite structure irradiated by the LED
Data Source
AI summary
The present disclosure relates to a lighting component which may comprise a light emitting diode (LED) or laser diode (LD) for generating at least one of blue light or ultraviolet light. A fluoride phosphor matrix may be included, which may be consolidated into a phosphor ceramic structure including at least one of a transparent fluoride ceramic structure or a translucent fluoride ceramic structure, and positioned adjacent to the LED or LD. The phosphor ceramic structure generates at least one of red or orange light when irradiated by the light emitted from the LED or LD. The phosphor ceramic structure exhibits reduced thermal quenching relative to a fluoride particulate structure irradiated by the LED or LD.