Aryl Thioether Polysiloxane Encapsulant for High Refractive Index LEDs
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Solution Overview
Problem
Current silicone encapsulants for high brightness LEDs have refractive indices limited to around 1.57, which is not sufficient for optimal light extraction and heat stability, as they yellow over time, and there is a need for materials with higher refractive indices and improved thermal stability.
Innovation Solution
Development of curable aryl (thio)ether aryl polysiloxane compositions that include silicon-bonded aryl (thio)ether groups, allowing for the creation of liquid polysiloxane prepolymers with refractive indices up to 1.62, which can be cured to form transparent, high refractive index encapsulants with minimal shrinkage and excellent heat stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional silicone encapsulants with refractive index around 1.57 are used, then the material maintains good heat stability, but the refractive index is insufficient for optimal light extraction
Solution Approach 1:
The patent changes the chemical composition parameters of the silicone encapsulant by incorporating aryl (thio)ether aryl groups and phenylsilyl groups in specific ratios. This compositional parameter change increases the refractive index from 1.57 to above 1.60 while maintaining heat stability through the selective arrangement of these functional groups in the polymer structure
Solution Approach 2:
The patent creates a composite silicone material combining multiple functional groups (aryl groups, thioether groups, phenylsilyl groups) within a single polymer system. This composite approach allows the material to simultaneously achieve high refractive index from the aromatic groups and heat stability from the silicone backbone and specific group interactions
2Illumination intensity
If epoxies are used as encapsulants, then the refractive index can be increased, but the material exhibits excessive yellowing over time
Solution Approach 1:
The patent replaces the conventional epoxy chemistry with a silicone-based chemistry that, while similar in refractive index capability, provides superior long-term optical stability. The silicone backbone with aryl (thio)ether aryl groups serves as a more durable alternative that resists yellowing degradation
Solution Approach 2:
The patent changes the chemical composition by using silicone-based aryl (thio)ether aryl groups instead of epoxy groups, fundamentally altering the material's chemical stability parameters while maintaining the desired refractive index properties
3Illumination intensity
If diphenylsiloxane monomers are used to achieve high refractive index, then the refractive index increases to 1.61, but the polymer becomes a solid rather than liquid
Solution Approach 1:
The patent introduces structural variation at the molecular level by incorporating different aryl (thio)ether aryl group configurations and phenylsilyl groups in specific ratios. This local structural differentiation prevents crystallization and maintains liquid state while preserving the high refractive index properties of the aromatic groups
Solution Approach 2:
The patent adjusts the compositional parameters by blending different silicon-based precursors with specific functional groups in controlled ratios. This parameter optimization allows the material to achieve the desired refractive index above 1.60 while maintaining liquid viscosity suitable for encapsulation applications
Data Source
AI summary
A curable aryl (thio)ether aryl silicon composition is disclosed. A cured aryl (thio)ether aryl polysiloxane composition is further disclosed, along with a method of making that cured aryl (thio)ether aryl polysiloxane composition from the curable aryl (thio)ether aryl silicon composition. An encapsulated semiconductor device, and a method of making that encapsulated semiconductor device by coating a semiconductor element of a semiconductor device with cured aryl (thio)ether aryl polysiloxane are further disclosed.