Micro LED Common Electrode Segmentation for Conductivity and Light Transmittance
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Solution Overview
Problem
The existing display panels using indium tin oxide (ITO) for common electrodes face challenges with high temperature resistance, flexibility, and light transmittance, leading to reduced light-emitting efficiency and manufacturing difficulties due to the thick, non-transparent, and poorly conductive nature of ITO electrodes.
Innovation Solution
A display apparatus with a common electrode that contacts the side surface of micro light-emitting devices, made of metallic materials like silver, gold, or conductive polymers, which exposes the upper surface of the second type electrodes, ensuring good electrical conductivity and light transmittance without covering the forward light-emitting surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO is used to form the common electrode with sufficient thickness for good electrical conductivity, then electrical conductivity is improved, but light transmittance deteriorates and light-emitting efficiency is lowered
Solution Approach 1:
The common electrode is divided into multiple sub-electrodes that are spatially separated and positioned between adjacent micro LEDs. This segmentation allows each sub-electrode to be thin enough for light transmittance while collectively providing sufficient conductivity through distributed contact points with the micro LED electrodes.
Solution Approach 2:
The common electrode transitions from a continuous planar layer to a three-dimensional structure with multiple contact points and varying heights. Some portions contact the first electrode while others contact the second electrode, creating vertical dimensionality that enables both conductivity and light transmission.
2Illumination intensity
If ITO is used as common electrode material, then light transmittance is improved, but flexibility and toughness deteriorate, increasing manufacturing difficulty
Solution Approach 1:
The material parameters of the common electrode are changed from transparent conducting oxide (ITO) to metals or conductive polymers. This parameter change sacrifices some light transmittance but dramatically improves flexibility, toughness, and ease of manufacturing while maintaining sufficient electrical conductivity through the segmented structure.
Solution Approach 2:
The common electrode uses composite material structures combining metals or conductive polymers with transparent insulating materials. This composite approach achieves a balance between flexibility/toughness and light transmittance, while the segmented configuration ensures adequate electrical conductivity.
3Reliability
If ITO common electrode completely covers the forward light-emitting surface, then electrical conductivity is improved, but light-emitting efficiency deteriorates
Solution Approach 1:
The common electrode is segmented into discrete portions positioned between micro LEDs rather than forming a continuous covering layer. This segmentation creates open spaces that allow light to pass through unobstructed while the segmented electrodes maintain electrical conductivity through contact with the micro LED electrodes at specific points.
Solution Approach 2:
The common electrode is extracted from its traditional continuous covering configuration and repositioned as separated elements between micro LEDs. This extraction removes the obstructive layer that blocked light while preserving the essential electrical connection function through strategic placement and contact with electrode surfaces.
Data Source
AI summary
A display apparatus includes a driving substrate, a plurality of micro light-emitting devices, and a common electrode. The micro light-emitting devices are separately arranged on the driving substrate, and each of the micro light-emitting devices includes an epitaxial structure, a first type electrode, and a second type electrode. The first type electrode and the second type electrode are disposed on opposite surfaces of the epitaxial structure. The common electrode is disposed on the driving substrate and located between the second type electrodes of the micro light-emitting devices, and the common electrode exposes an upper surface of each of the second type electrodes.