Conductive Mirror LED Structure for Light Extraction and Adhesion
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Solution Overview
Problem
Conventional LEDs face challenges in light extraction efficiency due to poor adhesion between the insulating material of the light-transmissive layer and the metallic material of the reflective layer, which can lead to reduced brightness, especially for light with shorter wavelengths.
Innovation Solution
The LED design incorporates an epitaxial layered structure and a conductive mirror structure with specific reflectance properties. The conductive mirror structure includes a first electrically conductive layer with a lower reflectance (R1) and a second electrically conductive layer with a higher reflectance (R2), where R1 < R2, to enhance light reflection and extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an adhesive layer (e.g., indium tin oxide) is formed between the reflective layer and the light-transmissive layer to improve adhesion, then the bonding strength between layers is improved, but the brightness of the LED is greatly reduced due to light absorption by the adhesive layer
Solution Approach 1:
The patent introduces a light-transmissive layer as an intermediary component between the reflective layer and the epitaxial structure. This light-transmissive layer serves as a mediator that provides both mechanical bonding support and optical transparency, allowing light to pass through while maintaining layer adhesion without requiring light-absorbing adhesive materials.
Solution Approach 2:
The patent changes the optical parameters of the reflective layer by using materials with high reflectance in specific wavelength ranges. By selecting reflective layer materials and configurations that reflect light in the emission spectrum of the LED, the system achieves high brightness while maintaining structural integrity through the light-transmissive intermediate layer.
2Productivity
If a light-transmissive layer with insulating material is disposed between the reflective layer and the epitaxial structure to improve light extraction, then the light extraction efficiency is improved, but the adhesion between the insulating material and metallic reflective layer is poor
Solution Approach 1:
The light-transmissive layer acts as an intermediary that bridges the epitaxial structure and the reflective layer. This intermediate layer provides both the light extraction function and the mechanical adhesion function, eliminating the need for separate adhesive layers that would compromise optical performance.
Solution Approach 2:
The patent employs composite material structures where the light-transmissive layer combines electrical insulation properties with mechanical adhesion capabilities. This composite approach allows the system to achieve both high light extraction efficiency and reliable bonding between dissimilar materials (insulating layer and metallic reflective layer).
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 design improves the light extraction efficiency and luminance of the LED by optimizing the reflectance properties of the conductive mirror structure, while also increasing the bonding strength between the light-transmissive structure and the conductive mirror structure.
Implementation Method 1
The first electrically conductive layer has a first reflectance R1 to light emitted from the epitaxial layered structure. The second electrically conductive layer has a second reflectance R2 to light emitted from the epitaxial layered structure. The first reflectance R1 is smaller the second reflectance R2
Data Source
AI summary
A light-emitting diode includes an epitaxial layered structure and a conductive mirror structure which includes a first electrically conductive layer and a second electrically conductive layer disposed on the epitaxial layered structure in such order. The first and second electrically conductive layers respectively have a first reflectance R1 and a second reflectance R2 to light emitted from the epitaxial layered structure, and R1<R2.