Triangular LED Substrate Light Extraction
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Solution Overview
Problem
Conventional LEDs suffer from reduced brightness and light extraction due to their quadrangular shape, which causes internal light reflection, and non-optimized electrode structures that shelter light and lead to current crowding.
Innovation Solution
A light-emitting device with a triangular substrate and a light-emitting stack featuring a first electrode at the geometric center and second electrodes with pads and extending parts along the sides, improving current spreading and luminous efficiency by reducing internal reflection and optimizing electrode placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a quadrangular substrate shape is used, then manufacturing is simple, but internal light reflection occurs reducing brightness
Solution Approach 1:
The patent changes the substrate shape from a conventional quadrangular symmetric shape to a triangular asymmetric shape. This asymmetric geometry eliminates the 90-degree interior angles that cause internal light reflection, allowing light to escape more efficiently from the LED device while maintaining manufacturing feasibility through standard semiconductor fabrication processes.
2Ease of manufacture
If conventional electrode structure is used, then manufacturing is simple, but light is sheltered and current crowds near electrodes
Solution Approach 1:
The patent extends the second electrode from a conventional planar pad configuration into three-dimensional extending parts that wrap around the sidewalls of the light-emitting stack. This dimensional extension allows the electrode to make contact with the semiconductor layer at multiple heights and positions, improving current spreading while minimizing light sheltering effects.
Solution Approach 2:
The second electrode is divided into multiple discrete pads positioned at different locations on the triangular substrate, with each pad having extending parts that reach toward the light-emitting stack. This segmentation allows current to enter at multiple points and distribute more uniformly across the active layer, reducing current crowding effects.
3Reliability
If electrodes are placed to maximize contact, then electrical connection is improved, but light emission is blocked
Solution Approach 1:
The electrode extending parts are strategically positioned to contact specific regions of the semiconductor layer while leaving other regions open for light emission. The first electrode contacts the n-type semiconductor layer at the bottom, while the second electrode pads and extending parts contact the p-type semiconductor layer at different locations, creating localized electrical connections that minimize overall light blocking.
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 triangular shape enhances light extraction and brightness, reducing forward voltage and improving luminous efficiency by up to 2.79% without encapsulating glue and 1.45% with encapsulating glue compared to conventional rectangular LEDs.
Implementation Method 1
When imposing a certain level of forward voltage to the LED via the electrodes, holes from the p-type semiconductor layer and electrons from the n-type semiconductor layer are combined in the active layer to release light.
Implementation Method 2
The substrate has sidewalls forming four 90° interior angles. An internal reflection of light inside the quadrangular LED may easily occur due to this kind of LED shape so that the light may hardly escape from the LED.
Data Source
AI summary
A light-emitting element, includes a substrate; a light-emitting stack formed on the substrate, including a triangular upper surface parallel to the substrate, having three sides and three vertexes; a first electrode formed on the light-emitting stack and located near a first vertex of the three vertexes of the triangular upper surface; and a second electrode formed on the light-emitting stack; including two second electrode pads respectively located near other two vertexes of the three vertexes; and a second electrode extending part extending from the second electrode pads, disposed along the three sides of the triangular upper surface.