Light-Emitting Device Electrode Segmentation for Light Extraction
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Solution Overview
Problem
Conventional light-emitting diodes face a trade-off between good current conductivity and light absorption due to the use of metal electrodes, leading to light intensity loss from shielding effects, while transparent conductive materials offer better light transmittance but inferior current conduction.
Innovation Solution
A light-emitting device design featuring a dielectric layer between electrodes, where the first electrode is coupled to a conductive layer and the second electrode is coupled to a transparent conductive layer, allowing for parallel current conduction without overlapping metal on the light-emitting stack, thereby minimizing light shielding and enhancing light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal is used as ohmic contact material, then good current conducting is achieved, but light absorbing increases causing light intensity loss
Solution Approach 1:
The device is divided into separate functional regions: a first electrode region with metal for current conduction, a light-emitting stack region for light generation, and a second electrode region with transparent conductive material for light extraction. This spatial segmentation allows each region to optimize its material properties without compromising the other functions.
Solution Approach 2:
A dielectric layer is introduced as an intermediary between the first electrode and the light-emitting stack, and another dielectric layer is placed between the light-emitting stack and the second electrode. These intermediary layers prevent direct contact between metal and the light path, eliminating the shielding effect while maintaining electrical connectivity through the conductive layers.
2Illumination intensity
If transparent conductive material is used as ohmic contact material, then light transmittance is improved, but current conducting becomes inferior
Solution Approach 1:
The device structure segments the current conduction function from the light extraction function. The first electrode with metal handles current conduction at one end, while the second electrode with transparent conductive material handles light extraction at the other end, allowing each material to perform its optimal function.
Solution Approach 2:
The solution transitions from a single-layer ohmic contact design to a multi-layer stacked architecture where current conduction and light extraction occur in different spatial dimensions and locations, enabling both requirements to be satisfied simultaneously without direct material compromise.
3Reliability
If metal lines are used as extending electrodes, then good current conducting is achieved, but shielding increases resulting in light intensity loss
Solution Approach 1:
The harmful shielding effect is extracted and removed from the light-emitting region by placing metal electrodes only at the ends of the device, parallel to the stacking direction. The extending electrodes are taken out from the light path area, eliminating the shielding problem while preserving current conduction through the end electrodes.
Solution Approach 2:
Instead of placing extending electrodes perpendicular to the stacking direction (which causes shielding), the design inverts the approach by extending electrodes parallel to the stacking direction at the ends, reversing the conventional layout to eliminate the harmful shielding effect.
Data Source
AI summary
Disclosed is a light-emitting device comprising a light-emitting stack having a length, a width, a first semiconductor layer, an active layer on the first semiconductor layer, and a second semiconductor layer on the active layer, wherein the first semiconductor layer, the active layer, and the second semiconductor layer are stacked in a stacking direction. A first electrode is coupled to the first semiconductor layer and extended in a direction parallel to the stacking direction and a second electrode is coupled to the second semiconductor layer and extended in a direction parallel to the stacking direction. A dielectric layer is disposed between the first electrode and the second electrode.