OLED Cathode Undercut Structure for Low IR Drop Aperture
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Solution Overview
Problem
Conventional top-emitting OLEDs face challenges in achieving high transparency and conductivity for cathodes, leading to issues with IR drop and reduced pixel aperture ratio due to the use of Mg/Ag materials and auxiliary cathodes.
Innovation Solution
The display panel design incorporates a first electrode layer with a sub-electrode structure embedded in undercut structures, connected to an auxiliary electrode layer and a metal line layer, which enlarges the overlapping connection area without reducing the aperture ratio, ensuring high transparency and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an auxiliary cathode is used to reduce electrical resistance, then conductivity is improved, but the aperture ratio is reduced
Solution Approach 1:
The patent transitions from a planar connection to a three-dimensional undercut structure. The auxiliary cathode connects to the surface cathode through an undercut structure that extends laterally beneath the pixel-defining layer, increasing the connection area without occupying additional planar space. This dimensional change allows the connection area to be enlarged while maintaining the aperture ratio.
Solution Approach 2:
The undercut structure is nested within the existing layer structure. The auxiliary cathode is positioned in the undercut region formed by etching the pixel-defining layer, creating a nested configuration where the connection structure is embedded within the pixel structure rather than occupying separate space.
2Reliability
If the overlapping connection area is enlarged to reduce electrical resistance, then conductivity is improved, but the aperture ratio is reduced
Solution Approach 1:
The patent creates a three-dimensional undercut structure that extends laterally beneath the pixel-defining layer. This allows the overlapping connection area to be increased in the vertical and lateral dimensions without increasing the planar footprint, thereby maintaining the aperture ratio while reducing electrical resistance.
Solution Approach 2:
The connection structure is segmented into multiple regions: the auxiliary cathode, the undercut structure, and the surface cathode. This segmentation allows the connection area to be distributed across multiple interfaces, increasing the total overlapping area without requiring a single large planar region.
Data Source
AI summary
A display panel, a manufacturing method thereof, and a display device are provided. In the display panel, a first undercut structure and a second undercut structure are formed along a vertical direction of an overlappingly connecting hole of the first electrode layer and the auxiliary electrode layer. Therefore, an overlappingly connecting area between the first electrode layer and the auxiliary electrode layer can be enlarged. As such, the first electrode layer can be ensured to have high transparency and good conductivity, thereby solving an issue of IP drop of the first electrode. In addition, by using this undercut structure as well as using a metal line layer to overlappingly connect the first electrode layer with the auxiliary electrode layer, the overlappingly connecting area between the first electrode layer and the auxiliary electrode layer can be enlarged without reducing an aperture ratio of the display panel.