Self-Assembled LED Display Layout for Precise Pixel Placement
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Solution Overview
Problem
Current display devices face challenges in improving the yield of the self-assembly process of light emitting diodes (LEDs), preventing LEDs from adhering to incorrect positions, enhancing light extraction efficiency, and minimizing the impact of ohmic contact electrodes on luminous efficiency.
Innovation Solution
The solution involves a display device design with a substrate having spaced low potential power lines, where LEDs are self-assembled using a magnet and electric field, featuring a side electrode on an insulating film, a reflective first electrode, and an ohmic contact electrode, along with an irregularity structure to improve assembly yield and light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a side electrode is formed to improve assembly alignment, then the self-assembly yield is improved, but the light extraction efficiency deteriorates due to low reflectance
Solution Approach 1:
The electrode structure is segmented into two distinct parts: a side electrode for alignment during self-assembly and a lower electrode for light reflection. This segmentation allows each part to optimize its function without compromising the other - the side electrode provides alignment guidance while the lower electrode ensures high light extraction efficiency
Solution Approach 2:
Different regions of the electrode structure are assigned different material properties: the side electrode portion has low reflectance to facilitate alignment detection, while the lower electrode portion has high reflectance to maximize light extraction. This local quality differentiation resolves the contradiction by allowing each region to have optimized properties for its specific function
2Reliability
If an ohmic contact electrode is formed to reduce resistance, then the electrical resistance is improved, but the light extraction efficiency deteriorates
Solution Approach 1:
The ohmic contact electrode is designed with local quality differentiation where only specific contact regions have high conductivity materials, while other regions maintain high reflectance properties. This allows the electrode to provide low resistance where needed for electrical contact while preserving light extraction efficiency in regions where electrical contact is not required
Solution Approach 2:
The electrode structure is divided into functional segments: ohmic contact regions for electrical connection and reflective regions for light extraction. This segmentation enables the ohmic contact electrode to fulfill its electrical function without uniformly compromising the light extraction performance across the entire electrode area
3Manufacturing precision
If LEDs are self-assembled using electric field between spaced power lines, then the assembly precision is improved, but the risk of LED adhesion to incorrect positions increases
Solution Approach 1:
The LED structure incorporates localized ferromagnetic side electrodes that create specific magnetic field interaction zones. These localized magnetic properties work in conjunction with the electric field from spaced power lines to provide precise positioning cues, ensuring LEDs adhere only to correct positions while maintaining high assembly precision
Solution Approach 2:
Ferromagnetic materials are introduced as an intermediary mechanism between the electric field and LED positioning. The ferromagnetic side electrodes mediate the interaction by providing additional magnetic field-based positioning cues that work alongside the electric field, thereby improving positioning reliability without compromising assembly precision
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
This approach enhances the yield of the self-assembly process, reduces LED misplacement, improves light extraction efficiency, and minimizes the negative effects of ohmic contact electrodes on luminous efficiency, resulting in improved display performance.
Implementation Method 1
moving the plurality of light emitting diodes to the substrate using a magnet
Implementation Method 2
applying a voltage to the pair of low potential power lines and forming an electric field between the pair of low potential power lines, the plurality of light emitting diodes self-assembled on the substrate between the pair of low potential power lines responsive to the electric field
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A display device includes a substrate in which a plurality of sub pixels are defined; a pair of low potential power lines are in a sub pixel of the plurality of sub pixels; and a plurality of light emitting diodes that overlap an area between the pair of low potential power lines. Each of the plurality of light emitting diodes includes a first semiconductor layer; an emission layer; a second semiconductor layer; a first insulating film that encloses side surfaces of the first semiconductor layer, the emission layer, and the second semiconductor layer; a side electrode on the first insulating film; and a first electrode that is in contact with a bottom surface of the first semiconductor layer and a lower part of the side electrode.