M-shaped Nano-structures for LED Light Extraction
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) suffer from low light extraction efficiency due to the higher refractive index of semiconductor materials compared to air, causing large-angle emitted light to be internally reflected and trapped within the device.
Innovation Solution
The implementation of a three-dimensional nano-structure array on the surface of the LED, specifically M-shaped nano-structures, which refract and reflect photons with large incident angles, enhancing light extraction efficiency by directing them out of the LED.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional smooth surface is used in LED, then manufacturing is simple, but light extraction efficiency is low due to internal reflection
Solution Approach 1:
The patent transitions from a two-dimensional smooth surface to a three-dimensional nano-structure array surface. The M-shaped nano-structures create multiple extraction surfaces at different angles and depths, enabling light to escape through multiple pathways and dimensions, thereby dramatically improving light extraction efficiency while maintaining manufacturing feasibility through selective area growth techniques
Solution Approach 2:
The M-shaped nano-structures feature curved surfaces with multiple facets and angles rather than flat planar surfaces. These curved geometries include upward-sloping and downward-sloping surfaces that refract and reflect light at various angles, preventing total internal reflection and enabling more efficient light extraction from the LED
2Loss of energy
If three-dimensional nano-structure array is implemented, then light extraction efficiency is improved, but device complexity increases
Solution Approach 1:
The complex three-dimensional surface is segmented into repeating M-shaped nano-structure units arranged in arrays. Each unit cell contains simplified geometric elements (upward-sloping and downward-sloping surfaces) that can be manufactured using standard selective area growth techniques, making the overall complex structure manufacturable through modular repetition
Solution Approach 2:
The patent optimizes specific geometric parameters of the M-shaped nano-structures, including the angles of upward-sloping and downward-sloping surfaces, the spacing between adjacent structures, and the depth of grooves. These parameter optimizations balance light extraction performance with manufacturing capabilities, achieving high efficiency without excessive complexity
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 three-dimensional nano-structure array significantly improves light extraction efficiency by refracting and reflecting internal light, increasing the amount of emitted light and reducing heat production.
Implementation Method 1
M-shaped nano-structures, which refract and reflect photons with large incident angles
Implementation Method 2
M-shaped nano-structures, which refract and reflect photons with large incident angles
Data Source
AI summary
A light emitting diode is provided. The light emitting diode includes a first semiconductor layer, an active layer, a second semiconductor layer, a first electrode and a second electrode. The active layer is sandwiched between the first semiconductor layer and the second semiconductor layer, and a surface of the second semiconductor layer which is away from the active layer is a light extraction surface of the LED. The first electrode is electrically connected with the first semiconductor layer. The second electrode electrically connected with the second semiconductor layer. A number of three-dimensional nano-structures are formed on the light extraction surface of LED, the number of the three-dimensional nano-structures are aligned side by side, and a cross section of each three-dimensional nano-structure is M-shaped.