Fluoride Phosphor Ceramics for Thermal-Stable High-Flux LEDs
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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 in a multicomponent ceramic structure, reduces thermal quenching and environmental degradation, while maintaining high quantum efficiency and chemical stability, using hot-pressing to achieve transparency and translucency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If red phosphor with broad emission bandwidth is used, then color rendering index is improved, but thermal quenching increases and efficacy decreases
Solution Approach 1:
The patent changes the physical state of the phosphor from powder to transparent ceramic form. This parameter change in the material's physical structure reduces thermal quenching while maintaining the beneficial emission properties for color rendering.
Solution Approach 2:
The patent uses composite material structure by combining phosphor particles with a transparent ceramic matrix. This composite approach allows the phosphor to maintain its emission characteristics while the ceramic matrix provides thermal management benefits that reduce quenching.
2Loss of energy
If red phosphor with narrow emission bandwidth is used, then efficacy is improved, but color rendering index deteriorates
Solution Approach 1:
The transparent ceramic form changes the optical and thermal parameters of the phosphor material. This allows achieving a balance between narrow emission for high efficacy and adequate color rendering by optimizing the ceramic's optical properties.
3Ease of manufacture
If phosphor powder in polymer matrix is used, then ease of manufacture is improved, but thermal conductivity decreases and long-term stability deteriorates
Solution Approach 1:
The patent transitions from polymer-composite to ceramic-composite material system. The ceramic matrix provides superior thermal conductivity compared to polymers, while the composite structure maintains manufacturability through established ceramic processing techniques.
Solution Approach 2:
Changing the matrix material from polymer to ceramic fundamentally changes the thermal conductivity parameter. The ceramic matrix provides high thermal conductivity that enables efficient heat removal, improving long-term stability while maintaining practical manufacturability.
4Productivity
If high flux LED package is used, then productivity is improved, but thermal quenching increases and excited state losses increase
Solution Approach 1:
The transparent ceramic form changes the thermal and optical parameters of the phosphor system. This enables the material to withstand higher excitation fluxes by efficiently conducting away heat, thereby reducing thermal quenching and excited state losses while maintaining high productivity.
5Reliability
If K2SiF6:Mn4+ phosphor is used, then color rendering index is improved, but environmental degradation increases due to water reactivity
Solution Approach 1:
The patent embeds the reactive K2SiF6:Mn4+ phosphor particles within an inert transparent ceramic matrix. This composite structure physically isolates the phosphor from environmental moisture, preventing water reactivity and degradation while preserving the phosphor's excellent color rendering properties.
Solution Approach 2:
The transparent ceramic matrix acts as an intermediary protective barrier between the phosphor particles and the external environment. This intermediary layer prevents direct contact between moisture and the water-reactive phosphor, eliminating environmental degradation issues.
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 enhances thermal conductivity, reduces thermal quenching, and improves long-term stability, enabling higher efficacy and color rendering index, with reduced Mn doping mitigating intensity droop and extending LED fixture lifetimes.
Implementation Method 1
a highly efficient (Ga,In)N semiconductor chip emits blue light (λmax ̃450 nm)... This blue light is then combined with partially down-converted green/yellow- and orange/red-emitting phosphors to produce white light
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.