High Refractive Index Glass Cladding for LED Efficiency
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Solution Overview
Problem
Conventional luminescence conversion LEDs experience high scattering and refractive index losses due to the use of materials with low refractive indices, such as epoxy resins and silicones, which limit their conversion efficiency and are not suitable for high-power LEDs with elevated temperatures.
Innovation Solution
The use of high refractive index glasses (n > 1.6, preferably n ≥ 1.7) as a cladding material for phosphors, which minimizes scattering and refractive index jumps, and incorporates garnet or oxinitride phosphors with refractive indices above 2, along with methods like sintering, spraying, or synthesizing phosphor particles in the glass melt to create a vitreous body with improved thermal resistance and optical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional cladding materials (epoxy resins, silicones) with low refractive indices are used, then the manufacturing is simple and ease of operation is maintained, but scattering losses and refractive index losses increase, reducing conversion efficiency
Solution Approach 1:
The patent changes the refractive index parameter of the cladding material from conventional low values (n=1.4-1.6 for epoxies and silicones) to high values (n>1.6, preferably n≥1.7) by using glass materials. This parameter change reduces scattering losses and refractive index losses at the phosphor-cladding interface, thereby improving luminescence conversion efficiency while maintaining manufacturability through established glass processing techniques
Solution Approach 2:
The patent employs composite glass materials that combine high refractive index properties with phosphor particles. The glass matrix serves as the cladding material containing embedded phosphor particles, creating a composite structure that simultaneously achieves high refractive index for reduced optical losses and provides a stable matrix for phosphor embedding, resolving the contradiction between optical efficiency and manufacturing ease
2Temperature
If conventional cladding materials are used, then the device complexity is low, but thermal stability is insufficient for high-power LEDs with elevated temperatures
Solution Approach 1:
The patent changes the thermal parameter of the cladding material by selecting glass materials with high thermal stability and resistance to heat, suitable for so called high power LEDs with junction temperatures substantially above 140° C. This parameter change enables the material to withstand elevated temperatures without degradation, maintaining structural integrity and optical properties under high-power operating conditions
Solution Approach 2:
The patent uses composite glass-phosphor materials where the glass matrix provides thermal stability and structural support while the embedded phosphor particles provide luminescence conversion. This composite structure resolves the contradiction by combining materials with complementary properties: glass for thermal stability and phosphor for optical function, enabling high-power LED operation
3Productivity
If high refractive index glass materials are used, then scattering losses are reduced and conversion efficiency improves, but the manufacturing precision requirements increase due to stricter material specifications
Solution Approach 1:
The patent changes the refractive index parameter to high values (n>1.6, preferably n≥1.7) to reduce scattering losses and improve conversion efficiency. While this increases material specification precision requirements, the use of well-established glass processing techniques and standardized glass compositions helps maintain manufacturing feasibility by leveraging existing industrial capabilities for producing glass materials with controlled optical properties
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
This approach enhances the luminescence conversion efficiency by reducing losses and maintaining transparency, while providing better thermal stability for high-power LEDs, particularly with the use of nanophosphors and specific glass compositions like barite crown and bismuth-containing glasses.
Implementation Method 1
the primary radiation of the chip being converted at least partially into longer wave radiation by a conversion element
Implementation Method 2
the refractive index of the vitreous body being higher than 1.6, preferably at least n=1.7
Implementation Method 3
Primary and secondary radiation is scattered on the powder particles of the phosphor, and this leads to scattering losses
Data Source
AI summary
A luminescence conversion LED having a radiation emitting chip that is connected to electrical connections and is surrounded by a housing that comprises at least a basic body and a cap, the chip being seated on the basic body, in particular in a cutout of the basic body, and the primary radiation of the chip being converted at least partially into longer wave radiation by a conversion element, wherein the cap is formed by a vitreous body, the conversion means being contained in the vitreous body, the refractive index of the vitreous body being higher than 1.6, preferably at least n=1.7.