Electroluminescent Display Bank Structure for Uniform Coating
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Solution Overview
Problem
The existing electroluminescent (EL) display devices face issues with uniformity and damage to the emitting layer, particularly when the emitting layer is formed using a solution process, leading to decreased aperture ratio and non-coating problems, which affect brightness and display quality.
Innovation Solution
The implementation of a dual bank structure with a hydrophilic first bank and a hydrophobic second bank, or a single bank with a round-corner shape, to prevent pile-up and non-coating issues, along with an insulating pattern covering the corners of the pixels to maintain aperture ratio and prevent electrode contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the emitting layer is formed by the solution process, then the manufacturing complexity is reduced, but the uniformity of the emitting layer deteriorates and non-coating problems occur
Solution Approach 1:
The patent applies local quality by creating different surface energy regions on the bank structure. The first bank portion has a first surface energy and the second bank portion has a second surface energy, which are different from each other. This allows the emitting layer solution to be guided to specific regions, ensuring uniform coating in the pixel region while preventing pile-up in the non-pixel region, thus resolving the contradiction between ease of manufacture and manufacturing precision.
2Ease of manufacture
If the emitting layer is formed by the solution process, then the production cost is reduced, but the aperture ratio decreases due to pile-up and non-coating issues
Solution Approach 1:
The patent uses local quality by differentiating the surface energy of different bank portions. The first bank portion (overlapping the electrode) has a first surface energy that prevents emitting layer formation, while the second bank portion (not overlapping the electrode) has a second surface energy that allows proper emitting layer coating. This ensures the aperture ratio is maintained by preventing pile-up in the pixel region while allowing cost-effective solution process manufacturing.
3Device complexity
If a conventional bank structure is used, then the device complexity is reduced, but the emitting layer uniformity deteriorates due to pile-up and non-coating problems
Solution Approach 1:
The patent implements local quality by dividing the bank into two portions with different surface energies. The first bank portion overlaps the electrode and has a first surface energy to prevent emitting layer formation, while the second bank portion does not overlap the electrode and has a second surface energy to enable proper emitting layer coating. This maintains relatively simple device structure while significantly improving emitting layer uniformity.
4Reliability
If the bank overlaps the electrode, then the electrode is protected, but the emitting layer cannot be formed uniformly due to pile-up
Solution Approach 1:
The patent applies local quality by creating distinct surface energy zones on the bank. The first bank portion overlaps the electrode with a first surface energy that prevents emitting layer formation, protecting the electrode while avoiding pile-up. The second bank portion does not overlap the electrode and has a second surface energy that allows uniform emitting layer formation in the pixel region, thus resolving the contradiction between electrode protection and emitting layer uniformity.
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
The proposed solution effectively prevents pile-up and non-coating issues, maintaining the aperture ratio and display quality by ensuring uniform emitting layer formation and preventing electrode contact, thereby enhancing the overall performance of the EL display device.
Implementation Method 1
a dual bank structure with a hydrophilic first bank and a hydrophobic second bank
Implementation Method 2
a dual bank structure with a hydrophilic first bank and a hydrophobic second bank
Implementation Method 3
an insulating pattern covering the corners of the pixels to maintain aperture ratio and prevent electrode contact
Data Source
AI summary
An electroluminescent display device includes a substrate; a pixel having a first lateral side and a second lateral side that intersects the first lateral side, the pixel including an emitting diode disposed over the substrate, the emitting diode including a first electrode, an emitting layer on the first electrode, and a second electrode on the emitting layer; an insulating pattern overlapping the first lateral side of the pixel and covering a first end of the first electrode at the first lateral side of the pixel; and a bank surrounding the pixel, wherein the bank overlaps the insulating pattern at the first lateral side of the pixel, and the bank at the second lateral side of the pixel covers a second end of the first electrode.