LED M-Shaped Nano-Structure 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, resulting in a significant portion of light being trapped within the device.
Innovation Solution
The implementation of a three-dimensional nano-structure array on the surface of the LED's semiconductor layers, specifically an M-shaped nano-structure array, which alters the motion direction of photons with large incident angles, allowing them to be extracted from the light emitting surface, thereby enhancing the light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional LED structure is used, then the device is simple to manufacture, but the light extraction efficiency is low due to internal reflection of large-angle light
Solution Approach 1:
The patent introduces a three-dimensional nano-structure array on the light emitting surface, transitioning from a conventional flat two-dimensional surface to a structured three-dimensional surface. This dimensional change creates multiple light extraction paths and reduces internal reflection, thereby improving light extraction efficiency without significantly complicating the manufacturing process
Solution Approach 2:
The patent modifies the surface geometry parameters by creating nano-scale protrusions and recesses with specific dimensions (protrusion height of 50-200nm, recess depth of 50-200nm). These parameter changes alter the optical properties of the surface, enabling more effective light extraction while maintaining manufacturing feasibility through established semiconductor fabrication techniques
2Loss of energy
If a three-dimensional nano-structure array is added to improve light extraction, then the light extraction efficiency increases significantly, but the device structure becomes more complex
Solution Approach 1:
The patent divides the light emitting surface into numerous discrete nano-scale protrusions and recesses arranged in an array pattern. This segmentation approach creates multiple independent light extraction sites, collectively improving overall light extraction efficiency while each individual nano-structure remains simple in form and manufacturable using standard lithography and etching processes
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 light extraction efficiency of the LED is significantly improved, achieving a 5-fold increase compared to LEDs without the three-dimensional nano-structure array, leading to enhanced light emission and reduced heat production.
Implementation Method 1
extraction efficiency of LEDs is low because typical semiconductor materials have a higher refraction index than that of air. Large-angle light emitted from the active layer may be internally reflected in LEDs
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
Data Source
AI summary
A light emitting diode is provided. The light emitting diode includes a first semiconductor layer, an active layer and a second semiconductor layer. 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 emitting surface. A first electrode is electrically 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 formed on the light emitting surface. The number of the three-dimensional nano-structure are aligned side by side, and a cross-section of thee three-dimensional nano-structure is M-shaped.