Auxiliary Wiring Alignment in OLED Common Electrodes
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Solution Overview
Problem
High-definition display devices face challenges in achieving low resistance for common electrodes while maintaining a high aperture ratio, as auxiliary wiring alignment precision is difficult, leading to potential light blocking and luminosity differences.
Innovation Solution
The implementation of self-aligning auxiliary wiring above the common electrode using a mask insulator, which allows for high precision alignment and prevents the auxiliary wiring from obstructing the light-emitting region, combined with a filler material for sealing and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If auxiliary wiring is arranged above a common electrode to reduce resistance, then electrical conductivity is improved, but alignment precision deteriorates leading to potential light blocking and aperture ratio decrease
Solution Approach 1:
A mask insulator layer is introduced as an intermediary between the common electrode and the auxiliary wiring. This mask insulator serves as a positioning reference that enables precise alignment of the auxiliary wiring above the bank structure, preventing the wiring from blocking light in the pixel region while maintaining low resistance through proper electrical connection to the common electrode
2Area of stationary object
If auxiliary wiring is arranged above a bank to maintain aperture ratio, then light emission is preserved, but alignment precision becomes difficult to achieve in high-definition displays
Solution Approach 1:
The mask insulator is formed in advance before depositing the auxiliary wiring material. This preliminary formation of the mask insulator creates a predefined positioning structure that guides the subsequent auxiliary wiring formation process, ensuring high alignment precision even in high-definition displays where the bank structure alone would be insufficient for precise positioning
3Illumination intensity
If transparent conductive film is used for common electrode to allow light transmission, then light extraction is improved, but resistance increases causing voltage drop and luminosity differences
Solution Approach 1:
The auxiliary wiring is electrically connected to the common electrode, merging the low-resistance metal auxiliary wiring with the transparent conductive common electrode. This combination allows the common electrode to maintain its light transmission properties while the auxiliary wiring provides additional conductive pathways that reduce overall resistance and prevent voltage drops across large pixel areas
Data Source
AI summary
A display device includes a plurality of pixels arranged on a substrate, a plurality of pixel electrodes, wherein each pixel electrode of the plurality of pixel electrodes corresponds to a pixel of the plurality of pixels, a bank between adjacent pixel electrodes of the plurality of pixel electrodes, wherein the bank exposes a part of the pixel electrodes, an electroluminescent layer on each of the plurality of pixel electrodes, a common electrode above the bank and the electroluminescent layer, a plurality of insulators on the exposed regions of the pixel electrodes, wherein the common electrode is between the insulators and the pixel electrodes, and an auxiliary wiring on the common electrode between adjacent insulators of the plurality of insulators, wherein a top surface of each insulator of the plurality of insulators is farther from the substrate than a top surface of the common electrode.