LED Substrate Nano-Structures Light Extraction
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, resulting in low external quantum efficiency.
Innovation Solution
The method involves forming a light emitting diode with a substrate that includes three-dimensional nano-structures on its 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 by approximately 4.7 times compared to conventional LEDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional flat substrate is used, then manufacturing is simple, but light extraction efficiency is low due to high refractive index
Solution Approach 1:
The patent applies curvature by forming three-dimensional nano-structures (protrusions or recesses) on the substrate surface instead of using a flat surface. These curved nano-structures transform light with large incidence angles into light with smaller angles, improving light extraction efficiency by approximately 4.7 times compared to conventional flat substrates.
Solution Approach 2:
The patent transitions from a two-dimensional flat substrate surface to a three-dimensional structured surface by forming nano-structures with heights or depths of 50-500 nm. This dimensional change creates additional light extraction pathways and modifies light propagation angles, resolving the contradiction between manufacturing simplicity and light extraction efficiency.
2Loss of energy
If three-dimensional nano-structures are formed on substrate surface, then light extraction efficiency is improved by 4.7 times, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes specific parameters of the nano-structures to balance performance and manufacturability: height or depth of 50-500 nm, diameter or width of 50-500 nm, and spacing of 50-500 nm between adjacent structures. By controlling these parameters within specific ranges, the patent achieves significant light extraction improvement while maintaining reasonable manufacturing complexity.
Solution Approach 2:
The patent applies nano-structures only to the substrate surface where light extraction occurs, rather than modifying the entire LED structure. This localized application improves light extraction efficiency at the critical interface while minimizing overall device complexity and maintaining simplicity in other portions of the device.
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 use of three-dimensional nano-structures on the substrate surface of the LED enhances light extraction efficiency, significantly improving the external quantum efficiency of the LED by transforming light with large incidence angles into light with smaller angles, resulting in improved light emission.
Implementation Method 1
forming a light emitting diode with a substrate that includes three-dimensional nano-structures on its surface, which enhances light extraction efficiency by transforming light with large incidence angles into light with smaller angles
Data Source
AI summary
A method for making a LED comprises following steps. A substrate having a first surface and a second surface is provided. A patterned mask layer is applied on a first surface. A number of three-dimensional nano-structures are formed on the first surface and the patterned mask layer is removed. A first semiconductor layer, an active layer and a second semiconductor layer are formed on the second surface. A first electrode and a second electrode are formed to electrically connect with the first semiconductor layer and the second semiconductor pre-layer respectively.