LED Light Extraction via 3D Nano-Structures
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The efficiency of conventional light emitting diodes (LEDs) is limited by the high refractive index of the P-type and N-type semiconductor layers, leading to low external quantum efficiency.
Innovation Solution
The implementation of a light emitting diode structure that includes a substrate, a first semiconductor layer, an active layer, and a second semiconductor layer with three-dimensional nano-structures on the light emitting surface, which enhances light extraction efficiency by transforming light with large incidence angles into light with smaller angles, thereby improving the overall light extraction intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional LED structure with planar semiconductor layers is used, then manufacturing is simple, but light extraction efficiency is low due to high refractive index
Solution Approach 1:
The patent transitions from a planar (2D) semiconductor layer surface to a three-dimensional nano-structure surface with protrusions and recesses. This dimensional change creates multiple light extraction interfaces and pathways, effectively reducing the impact of the high refractive index and improving light extraction efficiency by approximately 4.7 times compared to conventional planar LEDs.
Solution Approach 2:
The patent introduces curved and non-planar surface features through three-dimensional nano-structures with protrusions and recesses. These curved surfaces alter light propagation paths through refraction and reflection, enabling light that would otherwise be trapped by total internal reflection to escape, thereby significantly enhancing light extraction efficiency.
2Device complexity
If high refractive index semiconductor materials are used, then LED structure is simple, but external quantum efficiency is limited
Solution Approach 1:
The patent adds vertical dimensionality to the semiconductor layer surface through three-dimensional nano-structures. This creates multiple extraction interfaces that overcome the total internal reflection problem inherent in high refractive index materials, improving external quantum efficiency without changing the fundamental material composition or device architecture.
Solution Approach 2:
The patent modifies the surface morphology parameter of the semiconductor layer by introducing three-dimensional nano-structures with specific protrusion and recess features. This parameter change alters the optical properties at the interface, reducing reflection losses and enhancing light extraction while maintaining the simplicity of the base semiconductor material system.
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 described LED structure enhances light extraction intensity by approximately 4.7 times compared to conventional LEDs, addressing the limitations of refractive index-related efficiency issues.
Implementation Method 1
the second semiconductor layer (130) comprises a body (132) and a number of first three-dimensional nano-structures (134)... which enhances light extraction efficiency by transforming light with large incidence angles into light with smaller angles
Data Source
AI summary
An LED comprises a substrate, a first semiconductor layer, an active layer, a second semiconductor layer, a first electrode and a second electrode. The first semiconductor layer, the active layer, and the second semiconductor layer are stacked in that order and located on a surface of the substrate. A number of first three-dimensional nano-structures are located on a surface of the second semiconductor layer away from the active layer. The first three-dimensional nano-structures are linear protruding structures, a cross-section of each linear protruding structure is an arc. The present disclosure also relates to an optical element.