Light Emitting Device Dual Phosphor Layer Red Emission
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Solution Overview
Problem
Current light-emitting devices that employ LEDs and phosphors to produce white light struggle with achieving high color purity and luminous flux, particularly in emitting red light, due to inefficiencies in wavelength conversion and light leakage.
Innovation Solution
A light-emitting device design incorporating a GaN semiconductor light source, a first layer with a manganese-activated fluoride phosphor for initial wavelength conversion, and a second layer with a nitride phosphor for further conversion, optimized to minimize light leakage and enhance red light emission by controlling the thickness and composition of the phosphor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single phosphor layer is used for wavelength conversion, then the device structure is simple, but the color purity and luminous flux of red light emission are insufficient
Solution Approach 1:
The phosphor conversion system is segmented into two distinct layers: a first phosphor layer for initial wavelength conversion and a second phosphor layer for further conversion. This segmentation allows each layer to be optimized for specific wavelength ranges, improving overall red light emission efficiency and color purity while maintaining manageable structural complexity
Solution Approach 2:
The solution transitions from a single-layer phosphor structure to a multi-layer vertical architecture. By adding the dimensional aspect of layer stacking, the device achieves superior wavelength conversion performance and red light emission without significantly increasing overall device footprint or complexity
2Manufacturing precision
If phosphor layers are made thicker to improve wavelength conversion efficiency, then color purity improves, but light leakage increases and luminous flux decreases
Solution Approach 1:
The thick phosphor layer required for high color purity is segmented into two thinner layers. The first layer handles initial wavelength conversion while the second layer completes the conversion to red light. This segmentation reduces light leakage and maintains high luminous flux while achieving the necessary color purity through cumulative conversion efficiency
Solution Approach 2:
The invention optimizes the thickness parameters of each phosphor layer individually rather than using a single thick layer. By adjusting the thickness of the first and second phosphor layers separately, the device achieves optimal balance between color purity and light transmission, minimizing energy loss while maximizing red light emission
3Manufacturing precision
If a manganese-activated fluoride phosphor is used for initial conversion, then the emission peak narrowness improves color purity, but the conversion efficiency may be limited
Solution Approach 1:
The invention merges the strengths of two different phosphor materials: the manganese-activated fluoride phosphor provides narrow emission peak for color purity, while the nitride phosphor provides high conversion efficiency. By combining these materials in a two-layer structure, the device achieves both color purity and efficient energy conversion
Solution Approach 2:
The phosphor system uses composite material architecture with two distinct phosphor types. The first layer employs manganese-activated fluoride phosphor for its narrow emission characteristics, while the second layer uses nitride phosphor for efficient wavelength conversion, creating a composite system that leverages the complementary advantages of both materials
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 device achieves high color purity and luminous flux for red light emission by effectively converting blue light from the GaN source, reducing leakage and maintaining luminous flux over time, even under continuous operation.
Implementation Method 1
a first layer, and a second layer. The first layer covers at least a portion of the light source and includes a fluoride phosphor for wavelength conversion of light emitted from the light source
Implementation Method 2
The second layer covers at least a portion of the first layer and includes a nitride phosphor for wavelength conversion of light emitted from the light source and/or the first layer
Data Source
AI summary
The red light-emitting device includes a light source, a first layer covering at least a portion of the light source and containing a fluoride phosphor converting light emitted from the light source, and a second layer covering at least a portion of the first layer and containing a nitride phosphor converting light emitted from the light source and/or the first layer. An emission intensity ratio at an emission peak wavelength of the light source is greater than 0 and 0.1 or less, and the emission intensity ratio at the wavelength of the maximum emission peak in an emission spectrum of the light-emitting device is greater than 2.8, supposing the reference emission intensity that is the minimum emission intensity within the range of plus or minus 15 nm or 30 nm from the wavelength of the maximum emission peak in the emission spectrum of the light-emitting device is 1.