Multilayer Re-emission Layer for White Light LED Efficiency
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Solution Overview
Problem
Conventional light emitting devices have limitations in luminous efficiency, particularly in achieving a broad spectrum of white light emission with stability and reduced spectral variation.
Innovation Solution
A light emitting device structure incorporating a re-emission layer with varying indium compositions, disposed on a concavo-convex structure, which absorbs light of a first wavelength and emits a longer wavelength range, enhancing luminous efficiency and stability by reducing spectral variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional light emitting device uses a single-layer re-emission layer with uniform indium composition, then the device structure is simple and easy to manufacture, but the luminous efficiency is limited and spectral variation is high
Solution Approach 1:
The re-emission layer is divided into multiple sub-layers with different indium compositions (e.g., first re-emission layer with 10-20% In, second re-emission layer with 20-30% In, third re-emission layer with 30-40% In). This segmentation allows each sub-layer to emit at different wavelengths, collectively covering a broader spectrum and improving luminous efficiency while converting blue or UV light into white light with reduced spectral variation
Solution Approach 2:
Different regions of the re-emission layer have different indium compositions tailored to specific wavelength requirements. The lower layers have lower indium content for shorter wavelength emission, while upper layers have higher indium content for longer wavelength emission. This local quality variation optimizes the spectral output at each position, achieving high luminous efficiency and stable white light emission
2Reliability
If a light emitting device uses fluorescent substances for wavelength conversion, then the device structure is simple, but the spectral variation is high and luminous efficiency is limited
Solution Approach 1:
The indium composition parameter is systematically varied across different re-emission layers (from 10-20% In in the first layer to 30-40% In in the third layer). This parameter change directly controls the emission wavelength of each layer, enabling precise spectral control and reduced spectral variation. The gradual increase in indium content creates a smooth spectral distribution that stabilizes the white light output
Solution Approach 2:
The re-emission layer is constructed as a composite structure combining multiple nitride semiconductor materials with different indium compositions (InGaN layers with varying In content). This composite material approach allows each layer to contribute specific wavelength ranges to the overall emission spectrum, achieving high spectral stability and reduced variation while converting blue or UV pump light into stable white light
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 solution significantly improves luminous efficiency and stability by converting blue or UV light into a broad spectrum of white light, including red, green, and yellow, effectively replacing conventional fluorescent substances.
Implementation Method 1
the re-emission layer absorbs the light of the first wavelength range and the re-emission layer emits a light of a second wavelength range longer than the first wavelength range
Data Source
AI summary
A light emitting device includes a light emitting structure comprising a first conductivity type semiconductor layer, a second conductivity type semiconductor layer and an active layer disposed between the first conductivity type semiconductor layer and the second conductivity type semiconductor layer to emit a light of a first wavelength; and a re-emission layer disposed on the light emitting structure, the re-emission layer comprising a nitride semiconductor, wherein the re-emission layer absorbs the light of the first wavelength range and the re-emission layer emits a light of a second wavelength range longer than the first wavelength range, and the re-emission layer is configured of multi layers having different indium (In) compositions, respectively, and the indium content in the multi-layer is largest in a top layer of the multi-layers.