LED Current Spreading Layer with Graphene and Wavelength Conversion
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) face challenges in achieving high light extraction efficiency and color rendering index (CRI) while maintaining a compact size and low manufacturing costs, particularly in generating a wide range of wavelengths without the need for additional phosphors.
Innovation Solution
Incorporating a graphene sheet in the current spreading layer of the LED, which includes a plurality of wavelength conversion structures, allows for efficient current spreading and heat dissipation, enabling the generation of light with multiple wavelengths, including blue, green, and red, without the need for additional phosphors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional LED structures are used, then manufacturing is simpler, but light extraction efficiency is insufficient
Solution Approach 1:
The patent segments the LED structure into distinct functional layers including a light emitting layer with quantum dots, a wavelength conversion layer with phosphors, and a current spreading layer with graphene. This segmentation allows each layer to be optimized independently for its specific function while maintaining overall manufacturing feasibility through standardized layer-by-layer fabrication processes.
Solution Approach 2:
The patent employs composite materials throughout the structure, particularly combining quantum dots with phosphors in the wavelength conversion layer, and integrating graphene with conductive matrices in the current spreading layer. These composite structures enable simultaneous achievement of high light extraction efficiency and manageable manufacturing complexity.
2Illumination intensity
If additional phosphors are added to generate multiple wavelengths, then color rendering index improves, but device complexity increases
Solution Approach 1:
The patent merges the functions of multiple wavelength generation mechanisms into a single integrated wavelength conversion layer. Quantum dots and phosphors are combined in the same layer, allowing simultaneous generation of multiple wavelengths (blue, green, red) from a single ultraviolet pump source, thereby improving color rendering index without proportionally increasing device complexity.
Solution Approach 2:
The wavelength conversion layer is designed with multi-functionality, serving as both the quantum dot emission layer and the phosphor conversion layer simultaneously. This universal layer handles multiple wavelength conversions in one structure, reducing the need for separate layers and thereby controlling device complexity while achieving broad spectral output.
3Ease of manufacture
If current spreading layer uses conventional materials, then manufacturing is easier, but heat dissipation efficiency is insufficient
Solution Approach 1:
The patent changes the material parameter of the current spreading layer by incorporating graphene, which has exceptionally high thermal conductivity. This parameter change dramatically improves heat dissipation efficiency while the graphene can be integrated using existing deposition techniques, maintaining reasonable manufacturing ease.
4Area of moving object
If LED size is reduced, then occupying area decreases, but light extraction efficiency deteriorates
Solution Approach 1:
The patent addresses the size-efficiency tradeoff by optimizing the vertical stacking of functional layers rather than expanding horizontal area. The multi-layer structure with quantum dots, phosphors, and graphene creates efficient light extraction pathways in the vertical dimension, enabling compact footprint while maintaining high light extraction efficiency through controlled light propagation in the thickness direction.
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 enhances light extraction efficiency, improves the color rendering index, reduces the LED's size and manufacturing costs, and allows for the generation of white light by converting ultraviolet rays into a broad spectrum of wavelengths.
Implementation Method 1
a current spreading layer under the second conductivity type semiconductor layer... the current spreading layer includes a graphene sheet
Implementation Method 2
a current spreading layer including a graphene sheet is provided, so that the current spreading effect can be achieved and the heat dissipation efficiency can be improved
Implementation Method 3
a plurality of wavelength conversion structures in the current spreading layer... light having a blue wavelength, light having a green wavelength, and light having a red wavelength can be generated by a plurality of wavelength conversion structures
Data Source
Figure 1
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AI summary
A light emitting diode (1) includes a light emitting structure (9) including a plurality of compound semiconductor layers (3-7), a current spreading layer (13) under the light emitting structure, a plurality of wavelength conversion structures (15-19) in the current spreading layer, an electrode layer (23) under the current spreading layer, and an electrode (33) on the light emitting structure.