OLED Auxiliary Electrode Contact via Spacer Exposure
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Solution Overview
Problem
Existing organic light emitting display devices face challenges in ensuring proper contact between the opposite electrode and the auxiliary electrode, leading to issues such as unintentional luminance deviation and display quality problems due to the non-pixel area's small size and the need for precise alignment of the spacer and pixel defining layer.
Innovation Solution
The device incorporates a pixel electrode and an auxiliary electrode on the same layer, with a spacer and pixel defining layer that expose portions of both electrodes, allowing for contact between the opposite electrode and the auxiliary electrode through strategically designed openings, ensuring secure contact and reduced luminance deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the non-pixel area is made small to increase pixel density, then the resolution is improved, but the contact between opposite electrode and auxiliary electrode becomes unreliable
Solution Approach 1:
The patent divides the electrode structure into multiple segments: pixel electrode, auxiliary electrode, and multiple spacers positioned at different locations. This segmentation allows the contact path to be distributed across multiple points rather than relying on a single contact area, thereby maintaining reliable electrical connection even when the overall non-pixel area is minimized for high resolution.
Solution Approach 2:
The spacer acts as an intermediary element that bridges the pixel electrode and auxiliary electrode. By positioning the spacer strategically in the non-pixel area, it mediates the electrical connection between electrodes, ensuring reliable contact while allowing the non-pixel area to remain small for high-resolution displays.
2Reliability
If the spacer and pixel defining layer are precisely aligned to ensure proper contact, then the contact reliability is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent merges the spacer formation process with the pixel defining layer formation process into a single patterning step. By using the same photomask and processing conditions for both structures, the alignment complexity is significantly reduced while maintaining precise spatial relationship between the spacer and pixel defining layer, ensuring reliable electrode contact.
Solution Approach 2:
The spacer serves multiple functions: it defines the contact area between electrodes, acts as an insulating barrier in non-contact regions, and provides structural support. This multi-functionality reduces the need for additional dedicated alignment features, simplifying the overall manufacturing process while maintaining contact reliability.
3Reliability
If the contact area between opposite electrode and auxiliary electrode is increased, then the contact reliability is improved, but the pixel area is reduced
Solution Approach 1:
The patent applies local quality by concentrating the contact function in specific localized regions where spacers are positioned, rather than requiring a large continuous contact area. The spacer creates a defined contact zone with optimal electrical connection properties, while the rest of the pixel area remains maximized for light emission, thus maintaining both reliability and pixel area.
Data Source
AI summary
An organic light emitting display device includes a pixel electrode, an auxiliary electrode, a pixel defining layer, a spacer, a light emitting layer, and an opposite electrode. The pixel electrode and auxiliary electrode on a same layer and are separated and electrically isolated from each other. The pixel defining layer is on the pixel and auxiliary electrodes and exposes at least portions of the pixel and auxiliary electrodes. The spacer corresponds to portions of the auxiliary electrode and pixel defining layer and exposes at least a portion of the auxiliary electrode. The light emitting layer is on the pixel electrode. The opposite electrode is on the light emitting layer and the spacer and is in contact with the auxiliary electrode.