OLED Display Panel Auxiliary Electrodes for Brightness Uniformity
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Solution Overview
Problem
Large-sized OLED display panels face issues with in-plane voltage drop due to the large cathode layer area, leading to brightness uniformity problems, and existing evaporation processes struggle with irregular sub-pixel structures, resulting in poor overlap between the cathode layer and auxiliary electrode, causing abnormal displays.
Innovation Solution
A display panel design with auxiliary electrodes arranged close to the peripheral edges of sub-pixels, extending parallel to the long and short edges of the panel, allowing for effective overlap and electrical connection with the cathode layers, even with irregular sub-pixel structures, using existing evaporation equipment without additional development.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the cathode layer area is increased to meet large-sized display panel requirements, then the display panel size is improved, but in-plane voltage drop increases causing brightness uniformity deterioration
Solution Approach 1:
The cathode layer is divided into multiple segments by introducing auxiliary electrodes that disconnect the continuous cathode layer. This segmentation reduces the in-plane voltage drop across the large area by creating multiple smaller conductive paths, thereby improving brightness uniformity while maintaining large display panel size.
Solution Approach 2:
Auxiliary electrodes are introduced as intermediary conductive elements between the anode and cathode layers. These auxiliary electrodes provide additional charge injection paths and reduce the overall resistance of the cathode layer, mitigating the voltage drop issue in large-sized panels without requiring changes to the fundamental cathode layer structure.
2Ease of manufacture
If the evaporation process is used to form films on the entire surface with rectangular sub-pixels, then the manufacturing process is simplified, but irregular sub-pixel structures cannot achieve effective overlap between cathode layer and auxiliary electrode
Solution Approach 1:
The auxiliary electrodes are designed with a dual-layer structure including conductive portions and covering portions at different dimensions. The covering portions extend beyond the conductive portions to provide geometric flexibility, allowing the structure to accommodate both rectangular and irregular sub-pixel shapes while maintaining effective overlap through the evaporation process.
Solution Approach 2:
The auxiliary electrode structure parameters are optimized by adjusting the extension length and orientation of the covering portions relative to the sub-pixel edges. This parameter adjustment enables the same evaporation process to achieve effective overlap for different sub-pixel geometries without requiring process reconfiguration.
3Reliability
If auxiliary electrodes are arranged to overlap with cathode layer for large-sized panels, then overall resistance of cathode layer is reduced, but irregular sub-pixel structures result in poor overlap effect
Solution Approach 1:
The auxiliary electrodes are pre-configured with covering portions that extend beyond the conductive portions before the evaporation process. This preliminary geometric configuration ensures that regardless of the sub-pixel shape (rectangular or irregular), the evaporation process will naturally achieve sufficient overlap between the cathode layer and auxiliary electrode, guaranteeing reliable electrical connection.
Solution Approach 2:
The auxiliary electrode structure employs asymmetric design where the covering portions extend in specific directions relative to the conductive portions. This asymmetric configuration is optimized to match the geometry of irregular sub-pixels, ensuring that the extended covering portions always provide adequate overlap area for effective electrical connection regardless of the sub-pixel orientation or shape.
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 solution improves brightness uniformity and display effectiveness while reducing manufacturing costs by enabling effective overlap between the cathode layers and auxiliary electrodes, suitable for both rectangular and irregular sub-pixel structures, without the need for new evaporation equipment.
Implementation Method 1
deposition of tricolor sub-pixels is performed through an evaporation process
Data Source
AI summary
The present application relates to a display panel and a preparation method therefor. The display panel includes a plurality of auxiliary electrodes located on one side of a pixel limiting layer facing away from an array substrate, at least part of the auxiliary electrodes is located in pixel openings, second electrode layers are disconnected at edges of the auxiliary electrodes, the auxiliary electrodes include conductive portions and covering portions located on one sides of the conductive portions facing away from the array substrate, and orthographic projections of the covering portions on the array substrate cover orthographic projections of the conductive portions on the array substrate; and peripheral edges of the sub-pixels of the pixel units are not parallel to a direction where a long edge or a short edge of the display panel is located, the auxiliary electrodes are arranged close to the peripheral edge of the at least one sub-pixel, and the auxiliary electrodes extend parallel to the direction where the long edge and the short edge are located, so that ends of the second electrode layers are capable of overlapping with the conductive portions to achieve electrical connection.