Crosslinked Polysiloxane Matrix for LED Wavelength Conversion
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Solution Overview
Problem
Conventional wavelength converting materials for LEDs are limited in thermal and photo stability, and accurate control of thickness and concentration, which affects the longevity and color consistency of lighting devices, and there is a need for new materials that can handle high thermal stresses and intense light exposure.
Innovation Solution
Crosslinked polysiloxanes are used as a matrix material for wavelength converting elements, allowing for homogeneous distribution of luminescent particles without surfactants or surface modification, providing thermal and photo stability, and enabling adjustable thickness and elasticity for better light outcoupling and substrate conformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If ceramic materials are used for wavelength converting elements, then thermal stability is improved, but manufacturing complexity and cost increase due to high-temperature sintering and difficult post-production shaping
Solution Approach 1:
The patent changes the operating temperature parameter from high-temperature ceramic sintering (typically >1000°C) to low-temperature polymer processing (room temperature to <200°C). This is achieved by substituting ceramic matrix materials with polymer matrix materials, enabling wavelength converting elements to be manufactured without high-temperature sintering while maintaining thermal stability through careful material selection and crosslinking.
Solution Approach 2:
The patent employs inexpensive polymer materials (epoxies, polyesters, silicones) as alternatives to costly ceramic materials. These polymers can be processed at low temperatures using conventional manufacturing techniques, eliminating the need for expensive high-temperature furnaces and complex sintering procedures, thereby reducing both equipment investment and manufacturing costs.
2Stability of the object's composition
If ceramic materials are used for wavelength converting elements, then thermal stability is improved, but adaptability decreases due to limited material selection and difficulty in fine-tuning wavelength conversion
Solution Approach 1:
The patent creates composite wavelength converting elements by dispersing inorganic luminescent particles (such as YAG:Ce, Lu3Al5O12:Ce) within an organic polymer matrix. This composite structure combines the thermal stability of inorganic particles with the processing advantages and chemical versatility of polymers, enabling both thermal resistance and easy wavelength conversion tuning through particle selection and concentration adjustment.
Solution Approach 2:
The patent achieves wavelength conversion tuning by locally adjusting the concentration, size distribution, and type of luminescent particles within different regions of the polymer matrix. This allows independent optimization of optical properties in different zones while maintaining overall thermal stability, providing fine control over wavelength conversion characteristics.
3Ease of manufacture
If conventional polymers are used as matrix material, then ease of manufacture is improved, but thermal stability deteriorates due to degradation at high temperatures
Solution Approach 1:
The patent modifies the thermal performance parameter of conventional polymers through crosslinking chemistry. By introducing crosslinked networks via reactive functional groups (epoxy, hydroxyl, carboxyl, amine groups), the polymer matrix achieves enhanced thermal stability and dimensional stability while retaining the ease of low-temperature processing and molding that makes polymers attractive for manufacturing.
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 crosslinked polysiloxane matrix ensures stable and consistent light conversion, withstands high temperatures and intense light, and allows for flexible shaping and bonding with LEDs, enhancing the longevity and performance of LED-based lighting devices.
Implementation Method 1
a wavelength converting material that partially converts the emitted light into another color
Implementation Method 2
Luminescent particles can be dispersed in a polysiloxane which thereafter is crosslinked to form a solid body
Data Source
AI summary
A wavelength converting element (104), typically for a LED (101), is provided, comprising luminescent particles (105) dispersed in a matrix (106) comprising crosslinked polysiloxane. Crosslinked polysiloxanes are temperature stable, typically up to temperatures above 300° C., meaning that they are stable under normal operating conditions of light emitting diodes. Further, crosslinked polysiloxanes are stable towards exposure to light, meaning that they will not degrade/discolor as a consequence of high intensity light exposure. The polymeric wavelength converter can easily be shaped in different forms. This may lead to better outcoupling of the light from a LED-converter system.