LED Light Extraction via M-Shaped Nano-Structures
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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 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 protruding structures, which alter the motion direction of photons and enhance light extraction efficiency by acting as a patterned surface for the light emitting diode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional smooth surface is used for the LED, then the manufacturing process is simple, but the light extraction efficiency is low due to internal reflection of large-angle light
Solution Approach 1:
The patent transitions from a two-dimensional smooth surface to a three-dimensional nano-structure array surface. The M-shaped protruding structures create multiple surfaces at different angles and depths, providing additional pathways for light extraction and reducing internal reflection through increased surface complexity in the third dimension.
Solution Approach 2:
The patent employs curved and angled surfaces in the M-shaped protruding structures rather than flat planes. These curved surfaces redirect light at multiple angles, preventing total internal reflection and enhancing light extraction efficiency through geometric optics principles.
2Loss of energy
If a three-dimensional nano-structure array is implemented on the LED surface, then light extraction efficiency is improved by redirecting photons, but the device complexity increases
Solution Approach 1:
The patent divides the LED surface into multiple discrete M-shaped protruding structures arranged in an array. Each protruding structure acts as an independent light-redirection element, and their collective arrangement creates the overall light extraction enhancement while maintaining manufacturability through repetitive patterning.
Solution Approach 2:
The patent optimizes specific parameters of the M-shaped protruding structures, including height (50-200 nm), width (50-200 nm), and spacing (100-500 nm), to achieve maximum light extraction efficiency. These parameter optimizations balance performance improvement with manufacturing feasibility.
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 redirecting and extracting photons from the LED, increasing the amount of light emitted externally and reducing internal reflection.
Implementation Method 1
a three-dimensional nano-structure array (140) on a first surface of the substrate (100)... alter the motion direction of photons and enhance light extraction efficiency
Implementation Method 2
Large-angle light emitted from the active layer may be internally reflected in LEDs, so that a large portion of the light emitted from the active layer will remain in the LEDs, thereby degrading the extraction efficiency
Data Source
AI summary
A light emitting diode including a substrate, a first semiconductor layer, an active layer, and a second semiconductor layer is provided. The substrate includes a first surface and a second surface, and the second surface is a light emitting surface of the LED. The first semiconductor layer, the active layer, and the second semiconductor layer are stacked on the first surface in that order. A first electrode electrically is connected with the first semiconductor layer. A second electrode is electrically connected with the second semiconductor layer. A number of three-dimensional nano-structures are located on at least one surface of the substrate and aligned side by side, and a cross section of each of the three-dimensional nano-structure is M-shaped.