LED Current Concentrating Structure for Light Extraction
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Solution Overview
Problem
GaN-based LEDs with current-blocking structures face reduced light extraction efficiency due to current injection and emission being concentrated in the central region, leading to lower side light output and absorption by metal electrodes.
Innovation Solution
A 'sandwich' structure is implemented with a transparent insulating layer and multiple transparent conductive oxide layers, where the insulating layer has an inward recess relative to the first conductive oxide layer, redirecting current injection to the peripheral region, thereby enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a current-blocking structure is used in GaN-based LEDs, then the light extraction efficiency is reduced, but the current injection and emission are concentrated in the central region
Solution Approach 1:
The patent segments the current injection path by introducing a transparent insulating layer with an inward recess that divides the current distribution into central and peripheral regions. This segmentation allows different regions to have different current densities, with the peripheral region experiencing higher current injection to enhance light extraction efficiency while the central region maintains controlled current flow.
Solution Approach 2:
The patent applies local quality by creating a non-uniform current distribution across the LED structure. The transparent insulating layer with inward recess modifies the local electrical properties at different radial positions, causing the peripheral region to have higher current injection and the central region to have lower current injection, thereby optimizing light extraction at specific locations.
2Device complexity
If current is concentrated in the central region, then the device structure is simpler, but the side light output is reduced and absorption by metal electrodes increases
Solution Approach 1:
The patent transitions from a uniform two-dimensional current distribution to a three-dimensional structured distribution by introducing a transparent insulating layer with an inward recess. This dimensional change creates a radial current gradient that directs more current to the peripheral region, reducing metal electrode absorption while maintaining structural feasibility.
Solution Approach 2:
The transparent insulating layer acts as an intermediary element that mediates between the electrodes and the active layer. By introducing this intermediate structure with an inward recess, the patent controls current flow paths and reduces direct current injection into regions where metal electrodes would absorb light, thereby reducing harmful absorption effects.
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 current concentrating structure effectively prevents shading by the p-electrode and increases photon emission from the peripheral region, resulting in improved light extraction efficiency by redirecting current injection and enhancing side light output.
Implementation Method 1
the transparent insulating layer and the at least one transparent conductive oxide layer are configured to distribute a current through the LED more concentrated toward a peripheral region of the LED
Data Source
AI summary
A light emitting diode (LED) includes a transparent insulating layer; and at least one transparent conductive oxide layer substantially enclosing the transparent insulating layer, wherein the transparent insulating layer and the at least one transparent conductive oxide layer are configured to distribute a current through the LED more concentrated toward a peripheral region of the LED.