Sol-Gel Conversion Element for High CRI LED Thermal Stability
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Solution Overview
Problem
Conventional optoelectronic components, such as LEDs, face limitations in achieving high luminance and color rendering index (CRI) for warm white light at high current densities and stable operation under varying temperatures, due to thermal instability and the inability to combine multiple conversion materials effectively.
Innovation Solution
The development of an optoelectronic component with a self-supported conversion element comprising a substrate and a first layer with embedded conversion materials in a condensed sol-gel matrix, which allows for high thermal conductivity and stability against humidity and radiation, enabling efficient heat dissipation and combination of multiple conversion materials for enhanced luminance and CRI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional conversion elements with polymer matrix material are used, then the conversion element can be produced with multiple conversion materials, but the thermal stability is low
Solution Approach 1:
The patent employs a composite material system consisting of a glass ceramic matrix combined with specific conversion materials (YAG:Ce and CaAlSiN3:Eu). This composite structure allows the integration of multiple conversion materials while achieving high thermal stability through the glass ceramic binder, which maintains structural integrity at elevated temperatures unlike conventional polymer matrices.
2Stability of the object's composition
If conversion ceramics are used, then high thermal stability is achieved, but only one type of conversion material can be used
Solution Approach 1:
The invention creates a composite conversion element where a glass ceramic matrix serves as the binder phase, enabling the combination of different conversion material types (garnet-based YAG:Ce and nitride-based CaAlSiN3:Eu) while maintaining thermal stability. The glass ceramic composition is specifically designed to be chemically inert toward both conversion materials, preventing detrimental reactions during sintering and operation.
3Strength
If conventional conversion elements are made thicker for mechanical stability, then handling is improved, but heat dissipation is reduced
Solution Approach 1:
The patent utilizes controlled sintering parameters (temperature, pressure, time) to achieve high mechanical strength in thin conversion elements. By optimizing the sintering process of the glass ceramic matrix, the conversion element attains sufficient mechanical stability for handling while maintaining a thin profile that enables effective heat dissipation from the LED chip.
4Illumination intensity
If multiple conversion materials are combined for high CRI, then color rendering is improved, but the conversion element becomes thicker
Solution Approach 1:
The patent applies a layered structure where different conversion materials are positioned in specific regions: YAG:Ce conversion material is placed in a first region to convert blue light to yellow, while CaAlSiN3:Eu conversion material is placed in a second region to convert blue light to red. This spatial distribution of conversion materials with different local optical properties enables high CRI while maintaining a thin overall structure.
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 solution enables optoelectronic components to operate at higher current densities and temperatures with improved luminance and color rendering index, overcoming the limitations of conventional components by providing a stable and efficient light emission with high CRI across a range of temperatures.
Implementation Method 1
The conversion element is configured to convert the light emitted by the semiconductor layer sequence, in particular light with a wavelength in the blue spectral range, into light of a different, usually longer, wavelength. The conversion takes place using at least one conversion material.
Implementation Method 2
The matrix material is at least a condensed sol-gel material... enabling efficient heat dissipation... large amounts of heat are generated during operation of the optoelectronic component as a result of Stokes heat or loss by the quantum efficiency of the conversion element
Data Source
AI summary
An optoelectronic component and a method for producing an optoelectronic component are disclosed. In an embodiment an optoelectronic component includes a semiconductor layer sequence having an active region configured to emit radiation at least via a main radiation exit surface during operation and a self-supporting conversion element arranged in a beam path of the semiconductor layer sequence, wherein the self-supporting conversion element includes a substrate and subsequently a first layer, wherein the first layer includes at least one conversion material embedded in a matrix material, wherein the matrix material includes at least one condensed sol-gel material, wherein the condensed sol-gel material has a proportion between 10 and 70 vol % in the first layer, and wherein the substrate is free of the sol-gel material and the conversion material and mechanically stabilizes the first layer.