Micro-LED Bottom Surface Structure for Self-Assembly and Light Extraction
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Solution Overview
Problem
Existing display devices using light emitting diodes face challenges in yield improvement during self-assembly, non-transferring defects due to incorrect clustering, reduced light extraction efficiency, and issues with electrode burrs and encapsulation films.
Innovation Solution
The display device incorporates a substrate with defined sub-pixels, each containing a light emitting diode with a first uneven structure on its bottom surface, a ferromagnetic electrode on the side surface, and a reflective partition to enhance light extraction efficiency and reduce defects during transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If light emitting diodes are clustered together or bonded in an incorrect position during self-assembly, then manufacturing complexity increases, but non-transferring defects occur and yield decreases
Solution Approach 1:
The patent applies preliminary action by pre-forming uneven structures on the bottom surfaces of light emitting diodes before the self-assembly process. This pre-prepared surface geometry enables automatic positioning when LEDs are clustered, ensuring correct alignment without complex real-time control mechanisms during assembly.
Solution Approach 2:
The uneven structures on LED bottom surfaces enable self-service positioning during self-assembly. The geometric features automatically guide correct placement through physical interference patterns, allowing the system to self-correct positioning without external intervention or complex control systems.
2Loss of energy
If a conventional flat bottom surface is used on light emitting diodes, then manufacturing is simpler, but light extraction efficiency is reduced
Solution Approach 1:
The patent implements curvature by forming uneven structures on the bottom surfaces of light emitting diodes. These non-planar geometric features modify light extraction pathways and reduce total internal reflection, thereby improving light extraction efficiency compared to conventional flat surfaces.
3Loss of energy
If ferromagnetic electrodes with low reflectance are formed on side surfaces, then light extraction efficiency improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by forming ferromagnetic electrodes with low reflectance specifically on the side surfaces of light emitting diodes, while maintaining different electrode configurations on top and bottom surfaces. This localized optimization improves light extraction from side surfaces without compromising overall device performance or requiring complete redesign of all electrode structures.
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 design improves light extraction efficiency, reduces defects, and enhances luminance while simplifying the transfer process, leading to a high-yield, high-luminance display device with reduced power consumption.
Implementation Method 1
a first uneven structure formed on a bottom surface... improve the light extraction efficiency of the light emitting diode
Implementation Method 2
partially forming a ferromagnetic electrode having a low reflectance on a side surface of the light emitting diode
Implementation Method 3
a reflective partition is formed to enclose around a light emitting diode to reflect light extracted toward a side surface of the light emitting diode to an upper portion
Data Source
AI summary
A display device and a manufacturing method thereof are discussed. The display device can include a substrate in which a plurality of sub pixels is defined, and a light emitting diode which is disposed in each of the plurality of sub pixels and has a first uneven structure, the light emitting diode includes a first semiconductor layer which has a first uneven structure formed on a bottom surface, an emission layer on the first semiconductor layer, a second semiconductor layer on the emission layer, a first electrode disposed on at least a part of a side surface of the first semiconductor layer, and a second electrode disposed on the second semiconductor layer. Accordingly, the first uneven structure is formed below the light emitting diode to improve the light extraction efficiency of the light emitting diode.