Polysiloxane TiO2 Composite LED Encapsulant Refractive Index
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Solution Overview
Problem
Conventional silicone encapsulants for light emitting diodes (LEDs) have refractive indices limited to around 1.57, which hinders the achievement of higher refractive indices necessary for improved light extraction efficiency while maintaining flowability and thermal stability.
Innovation Solution
A curable liquid polysiloxane/TiO2 composite with TiO2 domains of less than 5 nm average size, formulated with specific siloxane prepolymer components, achieving a refractive index of 1.61 to 1.7 and remaining liquid at room temperature, enabling high refractive index and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional silicone encapsulants are used, then flowability and thermal stability are maintained, but refractive index is limited to around 1.57
Solution Approach 1:
The patent combines polysiloxane prepolymer with TiO2 domains to create a composite material that achieves high refractive index (1.61-1.7) while maintaining flowability. The TiO2 domains with average size of less than 5 nm are dispersed in the polysiloxane matrix, creating a composite that overcomes the limitations of conventional silicones.
Solution Approach 2:
The patent changes the chemical composition parameters by incorporating TiO2 domains into the polysiloxane structure and adjusting the molar ratios of different siloxane units (R43SiO1/2, R1(R2)SiO2/2, R3SiO3/2, R5xZySiO(4-x-y)/2) to achieve the desired refractive index while maintaining liquid state at room temperature.
2Use of energy by moving object
If high refractive index materials are used, then light extraction efficiency is improved, but flowability may be compromised
Solution Approach 1:
The composite of polysiloxane prepolymer and TiO2 domains provides high refractive index (1.61-1.7) for improved light extraction efficiency while the nanoscale TiO2 domains (less than 5 nm) ensure the material remains liquid and flowable at room temperature.
Solution Approach 2:
The TiO2 domains are distributed at the nanoscale throughout the polysiloxane matrix, providing localized high refractive index regions that enhance light extraction while the overall composite maintains the flowability needed for molding operations.
3Temperature
If TiO2 is added to increase refractive index, then optical performance improves, but material may solidify at room temperature
Solution Approach 1:
The patent carefully controls the composition parameters including the type and amount of polysiloxane prepolymer, the concentration of TiO2 domains (20-60 wt%), and the average domain size (less than 5 nm) to achieve refractive index of 1.61-1.7 while maintaining liquid state at room temperature and atmospheric pressure.
Solution Approach 2:
The patent uses a specific range of TiO2 content (20-60 wt%) which is sufficient to achieve high refractive index but controlled to prevent excessive solidification, and employs nanoscale domain sizes to maximize refractive index enhancement while minimizing impact on flowability.
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 composite provides a high refractive index of 1.61 to 1.7, maintaining flowability and excellent thermal stability, enhancing light extraction efficiency in LEDs without the need for solvents, thus overcoming the limitations of conventional silicone encapsulants.
Implementation Method 1
the curable liquid polysiloxane/TiO2 composite exhibits a refractive index of >1.61 to 1.7
Implementation Method 2
TiO2 domains having an average domain size of less than 5 nm
Data Source
AI summary
A curable liquid polysiloxane/TiO2 composite for use as a light emitting diode encapsulant is provided, comprising: a polysiloxane prepolymer with TiO2 domains having an average domain size of less than 5 nm, wherein the curable liquid polysiloxane/TiO2 composite contains 20 to 60 mol % TiO2 (based on total solids); wherein the curable liquid polysiloxane/TiO2 composite exhibits a refractive index of >1.61 to 1.7 and wherein the curable liquid polysiloxane/TiO2 composite is a liquid at room temperature and atmospheric pressure. Also provided is a light emitting diode manufacturing assembly.