Ring-Shaped LED Electrode Design for Light Extraction
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Solution Overview
Problem
Conventional light emitting diodes (LEDs) face limitations in light extract efficiency due to light absorption by electrodes and substrates, leading to uneven luminance, heat generation, and variability in driving voltage and lifetime among devices.
Innovation Solution
A light emitting device design featuring a semiconductor multilayer structure with a ring-shaped upper electrode, an interface electrode, a current blocking layer, and a reflecting layer to improve light extraction efficiency, uniform luminance and heat generation, and reduce dispersion in driving voltage and lifetime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional LED structure with a circular upper electrode is used, then the device is simple to manufacture, but light absorption by the electrode and substrate limits light extraction efficiency
Solution Approach 1:
The patent segments the current injection region into a concentric ring-shaped region with an inner diameter and an outer diameter greater than the upper electrode's outer diameter. This segmentation allows current to flow through the ring-shaped region to the lower electrode without passing through the active layer directly under the upper electrode, thereby reducing light absorption by the electrode and substrate while maintaining manufacturing simplicity
Solution Approach 2:
The patent introduces a vertical dimension to the current path by creating a concentric ring-shaped current injection region at the interface between the substrate and semiconductor multilayer structure. This three-dimensional current distribution enables light to be extracted from the side walls of the structure rather than being absorbed by the upper electrode, improving light extraction efficiency without complicating the manufacturing process
2Loss of energy
If interface electrodes are arranged in a matrix shape outside the current confining layer, then light absorption by the substrate is reduced, but differences in distances from the upper electrode cause uneven current distribution and heat generation
Solution Approach 1:
The patent positions the interface electrode such that its center coincides with the center of the upper electrode, creating a symmetric configuration where the distance from the upper electrode to the interface electrode is uniform in all radial directions. This equipotential arrangement ensures equal electrical resistance in all current paths, resulting in uniform current distribution and consistent heat generation across the light emitting region
Solution Approach 2:
The patent uses a concentric ring-shaped current injection region with specific inner and outer diameters that are asymmetrically positioned relative to the upper electrode. This asymmetric ring structure, combined with the centrally positioned interface electrode, creates a balanced current distribution pattern that prevents local current convergence while effectively reducing substrate light absorption
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 design enhances light extract efficiency, stabilizes luminance and heat generation, and minimizes variability in driving voltage and lifetime, resulting in improved performance and longevity of the LEDs.
Implementation Method 1
a reflecting layer electrically connected to the interface electrode, for reflecting a light transmitted through the current blocking layer that is a part of the light emitted from the light emitting layer to a side of said one surface of the semiconductor multilayer structure
Implementation Method 2
a semiconductor multilayer structure including a light emitting layer
Data Source
AI summary
An upper electrode is formed on one surface of a semiconductor multilayer structure including a light emitting layer. An interface electrode is formed at a region of another surface of the semiconductor multilayer structure except a region right under the upper electrode. A center of the interface electrode coincides with a center of the upper electrode. At least a part of the interface electrode has a similar shape to a shape of an outer periphery of the upper electrode. A current blocking layer is formed at another region of another surface of the semiconductor multilayer structure except the region where the interface electrode is formed. A reflecting layer for reflecting a part of the light emitted from the light emitting layer is electrically connected to the interface electrode. A conductive supporting substrate is electrically connected to the semiconductor multilayer structure.