Selective Filter Layer for Light Emitting Device
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Solution Overview
Problem
In light emitting devices, the use of phosphors for color conversion leads to optical losses due to re-absorption of emitted light, which degrades efficiency.
Innovation Solution
A light emitting device with a selective filter layer between the light emitting structure and the phosphor layer, comprising a stacked structure of dielectric layers with different refractive indices, transmits short-wavelength light and reflects long-wavelength light, preventing re-absorption and enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a phosphor layer is applied to convert light color, then color rendering is improved, but optical loss increases due to re-absorption of emitted light
Solution Approach 1:
The device is segmented into distinct functional layers: a light emitting structure, a phosphor layer for color conversion, and a selective filter layer for light management. This segmentation allows each layer to perform its specific function optimally while minimizing interference between layers, particularly reducing re-absorption losses by positioning the selective filter between the light source and phosphor.
Solution Approach 2:
A selective filter layer acts as an intermediary component between the light emitting structure and the phosphor layer. This intermediary selectively transmits high-energy light (blue/UV) to the phosphor while reflecting low-energy light (yellow/red) back, preventing re-absorption and improving overall light extraction efficiency while maintaining color rendering.
2Illumination intensity
If light is emitted forward from phosphor, then color conversion is achieved, but light extraction efficiency decreases due to re-absorption in the device
Solution Approach 1:
The selective filter layer performs preliminary anti-action by reflecting low-energy light back toward the light source before it can be re-absorbed by the phosphor or light emitting structure. This preventive measure stops the re-absorption process before it occurs, maintaining high light extraction efficiency while enabling effective color conversion.
Solution Approach 2:
The selective filter layer changes the optical parameters of light passing through it by wavelength, selectively transmitting high-energy light while reflecting low-energy light. This parameter-based differentiation allows the system to optimize both color conversion and light extraction efficiency simultaneously by treating different wavelengths differently.
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 effectively increases light extraction efficiency by transmitting high-energy light and reflecting low-energy light, improving the color rendering index and reducing optical losses.
Implementation Method 1
a selective filter layer between the light emitting structure and the phosphor layer, comprising a stacked structure of dielectric layers having different refractive indices, to transmit the short-wavelength light and reflect the long-wavelength light
Implementation Method 2
a selective filter layer between the light emitting structure and the phosphor layer, comprising a stacked structure of dielectric layers having different refractive indices, to transmit the short-wavelength light and reflect the long-wavelength light
Implementation Method 3
P-N junction diodes having the properties of converting electrical energy into light energy may be formed by combining group III and V elements on the periodic table
Implementation Method 4
combining a phosphor and a blue or ultra violet light source
Data Source
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AI summary
Provided are a light emitting device, a light emitting device package, and a lighting system. The light emitting device includes a light emitting structure, a buffer layer on the light emitting structure, and a filter layer on the buffer layer.