OLED Array Substrate Acute-Angled Pixel Define Layer Ink Uniformity
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Solution Overview
Problem
Inkjet printing technology for OLED displays faces issues with ink uniformity and the 'coffee ring effect' due to ink climbing on the pixel define layer, affecting display quality, and there are challenges with the reliability and yield of the array substrate due to open circuit defects in the second electrode.
Innovation Solution
The array substrate design features a pixel define layer with acute-angled openings forming a capillary structure to prevent ink climbing, and an electrode repairing material layer with microcapsules containing nano silver electrode material that breaks to repair the second electrode, ensuring even ink distribution and improved conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If inkjet printing is used to form the light-emitting layer, then the manufacturing flexibility and color accuracy are improved, but the ink uniformity deteriorates due to the coffee ring effect
Solution Approach 1:
The pixel define layer is formed in advance with a specific structure (acute-angled openings) that prevents ink climbing before the inkjet printing process occurs. This preliminary structural preparation eliminates the coffee ring effect by controlling ink flow at the pixel boundaries, ensuring uniform ink distribution within each pixel region.
Solution Approach 2:
The pixel define layer is positioned only at specific locations (pixel boundaries) rather than covering the entire substrate. The acute-angled openings are locally configured at the edges of pixel regions where ink climbing occurs, while the center regions maintain open structures that allow uniform ink deposition. This localized intervention preserves manufacturing flexibility while improving ink uniformity.
2Manufacturing precision
If the pixel define layer has vertical walls to prevent ink climbing, then the ink uniformity is improved, but the manufacturing complexity increases
Solution Approach 1:
Instead of using vertical walls that would require complex multi-step patterning processes, the invention employs asymmetric acute-angled openings with specific angle ranges. This asymmetric geometry naturally prevents ink climbing through capillary action control while being formable through simpler single-step or reduced-step patterning processes, thus reducing manufacturing complexity while maintaining ink uniformity.
3Reliability
If the second electrode is formed as a continuous layer, then the electrical conductivity is improved, but the yield deteriorates due to open circuit defects
Solution Approach 1:
The electrode repairing material layer is incorporated into the pixel define layer structure in advance, positioned to cover potential defect locations on the second electrode. This preliminary protective layer acts as a cushion against open circuit defects, allowing the second electrode to be formed as a continuous layer for good conductivity while the repairing material compensates for any defects that occur during manufacturing, thus maintaining high yield.
Solution Approach 2:
The electrode repairing material layer serves as a sacrificial element that can be discarded (removed or degraded) to reveal and repair defective portions of the second electrode. This recovering mechanism allows the continuous layer structure to maintain electrical conductivity while providing a built-in repair function that improves yield by correcting open circuit defects after electrode formation.
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 design enhances the uniformity of the film formed by inkjet printing and improves the reliability and yield of the array substrate by preventing ink climbing and repairing potential defects in the second electrode, leading to better display performance.
Implementation Method 1
the pixel define layer has a plurality of openings each having two opposite surfaces, the two opposite surfaces including a first surface proximal to the base substrate and a second surface distal from the base substrate... forming a capillary structure to prevent ink climbing
Implementation Method 2
the shell of the microcapsule is broken by irradiating a side of the pixel define layer distal from the base substrate with ultraviolet light such that the electrode material in the microcapsule flows out
Data Source
AI summary
Disclosed is an array substrate including a base substrate, and a first electrode, a pixel define layer, a light-emitting layer and a second electrode which are sequentially disposed on the base substrate. The pixel define layer has a plurality of openings each having two opposite surfaces. The two opposite surfaces include a first surface proximal to the base substrate and a second surface distal from the base substrate. The second surface is coplanar with a surface of the pixel define layer distal from the base substrate. An orthographic projection of the second surface on the base substrate is within an orthographic projection of the first surface on the base substrate. The pixel define layer includes a pixel define body and an electrode repairing material layer. The electrode repairing material layer is disposed on a side of the pixel define body, and repairs the second electrode.