Polysiloxane Wavelength Converter for High-Temperature LED Stability
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Solution Overview
Problem
Current down-conversion elements in LED technology, such as ceramic and phosphor-in-glass converters, face challenges in stability at elevated temperatures, particularly above 200°C, due to difficulties in densifying certain nitride or oxynitride phosphors and incorporating them into glass matrices without damage, while phosphor-in-silicone converters are not stable enough for long-term high-temperature applications.
Innovation Solution
A wavelength converter comprising a non-luminescent substrate layer and one or more polysiloxane layers with a phosphor material, where the polysiloxane layers are prepared using a method involving a slurry of polysiloxane precursor and phosphor material, applied in a two-step curing process, providing a thermally stable and photo-thermally stable configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic or phosphor-in-glass converters are used, then thermal stability is improved, but manufacturing difficulty increases due to inability to densify certain nitride or oxynitride phosphors and damage to phosphor powder during glass matrix incorporation
Solution Approach 1:
The patent uses a composite material system consisting of a glass matrix combined with a silicone-based binder to create a phosphor-in-glass-silicone converter. This composite approach allows the glass to provide thermal stability while the silicone binder protects phosphor particles during processing and curing, enabling the incorporation of nitride and oxynitride phosphors that cannot be densified into ceramics.
Solution Approach 2:
The silicone-based binder acts as an intermediary material between the glass matrix and phosphor particles. It protects the phosphor powder during high-temperature glass melting and facilitates the incorporation of phosphors that would otherwise be damaged by the glass melting process or impossible to densify into ceramic form.
2Ease of manufacture
If phosphor-in-silicone converters are used, then ease of manufacture is improved, but thermal stability deteriorates as optical silicones are not stable enough for long-term operation at temperatures near or above 200°C
Solution Approach 1:
The patent creates a composite material system combining glass matrix with silicone-based binder. The glass component provides the high-temperature stability needed for operation above 200°C, while the silicone binder maintains the ease of manufacture and phosphor incorporation advantages of pure silicone converters.
Solution Approach 2:
The patent changes the chemical composition parameters of the binder material from pure organic silicone to a silicone-based binder containing inorganic components. This compositional change enables the binder to withstand high temperatures while retaining the processing advantages of silicone materials.
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 solution achieves enhanced thermal stability and photo-thermal stability, allowing the wavelength converter to operate effectively for thousands of hours at elevated temperatures, with the polysiloxane matrix providing a stable environment for the phosphor material close to the light source, improving the performance and longevity of LED devices.
Implementation Method 1
application of a first cure step, and application of a second cure step
Implementation Method 2
down-conversion elements, i.e., wavelength converters, are used that can efficiently down-convert higher energy light into lower energy light
Data Source
AI summary
The present invention is directed to a wavelength converter comprising a non-luminescent substrate layer, at least one polysiloxane layer, wherein at least one of the polysiloxane layers comprises a phosphor material.Furthermore, the present invention is directed to a method for preparing a wavelength converter, a light emitting device and a method for preparing a light emitting device.