LED Substrate Ceramic Composite Light Conversion
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Solution Overview
Problem
Existing white light-emitting diodes using nitride-based compound semiconductors face issues with color unevenness due to uneven distribution of fluorescent powder and lattice mismatch, leading to device deterioration and poor performance.
Innovation Solution
A substrate with a single crystal layer and a ceramic composite layer for light conversion, where the ceramic composite is formed from entangled metal oxide phases capable of emitting fluorescence, allowing for direct light emission and mixing without fluorescent powder, and using a bonding layer to facilitate bonding at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a coating layer containing fluorescent powder is applied on the front surface of a blue light-emitting element, then white light can be obtained by mixing blue and yellow light, but color unevenness occurs due to uneven distribution of fluorescent powder
Solution Approach 1:
The patent extracts the fluorescent powder from the coating layer and integrates the fluorescent material directly into the substrate. This eliminates the coating layer containing unevenly distributed fluorescent powder and replaces it with a substrate that inherently possesses light-emitting functionality through embedded fluorescent particles, thereby solving the color uniformity problem while maintaining white light emission capability
Solution Approach 2:
The patent merges the substrate and fluorescent material into a single integrated structure where fluorescent particles are embedded within the substrate matrix. This combination eliminates the separate coating layer and achieves uniform distribution of fluorescent material throughout the substrate, resolving the color unevenness issue while preserving the blue-yellow light mixing function
2Manufacturing precision
If a nitride semiconductor layer is formed on a YAG:Ce fluorescent single crystal substrate, then homogeneous yellow fluorescence can be obtained, but lattice mismatch between substrate and semiconductor layer prevents good-quality layer formation
Solution Approach 1:
The patent employs a composite substrate structure consisting of a base material with embedded fluorescent particles rather than a conventional fluorescent single crystal. This composite approach allows independent optimization of the base substrate for lattice matching with the nitride semiconductor layer while incorporating fluorescent material for yellow light emission, thereby simultaneously achieving good layer quality and homogeneous fluorescence
Solution Approach 2:
The patent segments the substrate functionality into two distinct components: a base substrate material optimized for lattice matching and semiconductor layer growth, and separately incorporated fluorescent particles providing yellow light emission. This segmentation allows each component to be optimized independently, resolving the conflict between layer quality and fluorescence homogeneity
3Device complexity
If fluorescent powder is used in a coating layer, then the device structure is simple, but uneven distribution of fluorescent powder causes color unevenness
Solution Approach 1:
The patent extracts the fluorescent powder from the coating layer and relocates it to the substrate. This extraction eliminates the need for a separate coating layer with fluorescent powder, simplifying the overall device structure while achieving uniform color distribution through the embedded fluorescent particles in the substrate
Solution Approach 2:
The patent merges the substrate and fluorescent material into an integrated structure where fluorescent particles are embedded within the substrate matrix. This merging eliminates the separate coating layer while maintaining the light conversion function, achieving both structural simplicity and color uniformity
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 approach enables the production of white light-emitting diodes with reduced color unevenness and improved durability by effectively mixing blue and yellow light, simplifying the production process and allowing for control of color tone.
Implementation Method 1
a ceramic composite layer for light conversion comprising a solidified body having formed therein at least two or more oxide phases selected from a single metal oxide and a complex oxide to be continuously and three-dimensionally entangled with each other, wherein at least one oxide phase in the solidified body contains a metal element oxide capable of emitting fluorescence
Data Source
AI summary
A substrate for light-emitting diodes, obtained by stacking a single crystal layer to form a light-emitting diode element onto a ceramic composite layer for light conversion, the ceramic composite layer having been formed by a unidirectional solidification method so that the ceramic composite layer comprises a solidified body having formed therein at least two or more oxide phases selected from single metal oxides and complex metal oxides to be continuously and three-dimensionally entangled with each other, with each oxide phase having a single crystal orientation, wherein at least one oxide phase out of the oxide phases in the solidified body contains a metal element oxide capable of emitting fluorescence.