Sequential Luminophoric Layer Fabrication for LED Color Rendering
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) have limited color rendering index due to their narrow wavelength distribution, making it difficult to produce high-quality white light with improved color accuracy.
Innovation Solution
The fabrication of light emitting devices involves the sequential deposition of luminophoric layers with specific absorption and emission spectra, where the shorter-wavelength end of one layer's emission spectrum overlaps with the longer-wavelength end of another layer's absorption spectrum, increasing the color rendering index by arranging the layers to minimize reabsorption and enhance color reproduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple luminophoric layers are deposited sequentially to improve color rendering index, then color accuracy and warmth of white light are enhanced, but device complexity and manufacturing process complexity increase
Solution Approach 1:
The luminophoric material is divided into multiple separate layers, each with specific absorption and emission spectra characteristics. The first luminophoric layer has a first absorption spectrum and first emission spectrum, while the second luminophoric layer has a second absorption spectrum and second emission spectrum. This segmentation allows each layer to perform a specific function in the overall color conversion process, thereby improving the color rendering index of the LED device.
Solution Approach 2:
The patent extends the color conversion process from a single-layer approach to a multi-layer vertical structure. By arranging luminophoric layers in sequence along the light path direction, the system utilizes the dimensional aspect to achieve progressive wavelength conversion. The spectral overlap condition (shorter-wavelength end of one layer's emission spectrum overlaps with the longer-wavelength end of another layer's absorption spectrum) enables efficient energy transfer across multiple dimensions of the electromagnetic spectrum.
2Measurement precision
If multiple luminophoric layers are deposited sequentially to improve color rendering index, then color accuracy and warmth of white light are enhanced, but manufacturing process complexity increases
Solution Approach 1:
The conductive pedestals are formed in advance on the LED chip before the luminophoric layers are deposited. The first conductive pedestal protrudes from the first face of the LED, and the second conductive pedestal protrudes from the second face of the LED. This preliminary formation of conductive structures facilitates subsequent alignment and deposition processes, thereby managing manufacturing complexity.
Solution Approach 2:
Different regions of the LED device are assigned different functional properties. The first luminophoric layer is deposited on the first conductive pedestal and has specific absorption and emission spectra tailored for its location, while the second luminophoric layer is deposited on the second conductive pedestal with different spectral characteristics. This local optimization of material properties enables precise control over the overall color rendering performance.
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 significantly enhances the color rendering index of LEDs, allowing for the production of white light with improved color accuracy and warmth, suitable for various lighting applications.
Implementation Method 1
A first luminophoric layer is coated on the face, including on the first conductive pedestal
Implementation Method 2
A second luminophoric layer is coated on the first luminophoric layer and on the second conductive pedestal
Implementation Method 3
the shorter-wavelength end of one layer's emission spectrum overlaps with the longer-wavelength end of another layer's absorption spectrum
Data Source
AI summary
An LED includes a first pedestal and may be fabricated by coating a first phosphor layer on the LED, thinning the first phosphor layer to expose the first pedestal, forming a second pedestal on the first pedestal, coating a second phosphor layer and thinning the second phosphor layer to expose the second pedestal. Alternatively, an LED having a pedestal is coated with a first phosphor layer, coated with a second phosphor layer and then planarized to expose the pedestal. Related structures are also provided.