OLED Column Bank Liquid Repellency for Ink Separation
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Solution Overview
Problem
Display panels using organic light-emitting diodes face issues such as display defects due to color mixture, decreased opening ratio, and variations in organic light-emitting layer thickness, primarily caused by the accidental spreading of ink onto column banks during the inkjet process.
Innovation Solution
The method involves forming display panels with varying heights and liquid repellency of column banks to control the spreading of inks, ensuring that inks of the same color do not mix and that the thickness of organic light-emitting layers remains consistent, by adjusting the ink-separating capability and liquid repellency of the column banks without increasing their width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If column banks are formed with a great width to prevent color mixture, then color mixture is prevented, but the opening ratio decreases
Solution Approach 1:
The patent applies different liquid repellency properties to different regions of the column banks. Specifically, the upper surfaces of the column banks are made more liquid-repellent than the side surfaces, creating localized functional differences. This allows the column banks to effectively repel ink in the critical spreading direction while maintaining structural integrity and minimizing overall width, thus preventing color mixture without sacrificing opening ratio.
Solution Approach 2:
The patent changes the liquid repellency parameter of the column bank surfaces by forming a specific layer structure. The column banks include a base layer and an upper layer with different liquid repellency characteristics. The upper layer is designed to have higher liquid repellency, which dynamically controls ink spreading behavior during the inkjet process, allowing narrow column banks to effectively prevent color mixture.
2Productivity
If the thicknesses of the light-emitting layers are made smaller, then the differences in thicknesses of the light-emitting layers increase
Solution Approach 1:
The patent prepares the column bank surfaces in advance with specific liquid repellency properties before the inkjet process. The upper surfaces of the column banks are pre-treated to be more liquid-repellent, which creates controlled boundaries that guide ink spreading during deposition. This preliminary preparation ensures that even small volumes of ink form uniform layers, reducing thickness variations while maintaining small layer thicknesses for high productivity.
Solution Approach 2:
The patent creates a self-regulating system where the liquid-repellent column bank surfaces provide real-time feedback during ink deposition. When ink approaches the column bank boundaries, the high liquid repellency of the upper surfaces automatically limits further spreading, preventing over-deposition. This feedback mechanism ensures uniform thickness control without requiring complex external monitoring, enabling consistent quality even with small layer thicknesses.
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 approach effectively prevents color mixture and ensures uniform thickness of organic light-emitting layers, maintaining a high opening ratio and improving the overall performance of the display panels by allowing for sufficient ink application and retention.
Implementation Method 1
forming, on the substrate, a first column bank between the first lower electrode and the second lower electrode, and a second column bank between the second lower electrode and the third lower electrode... adjusting the ink-separating capability and liquid repellency of the column banks
Implementation Method 2
The solutions are ejected so as to land at the X-axis direction centers of the regions between the column banks... the upper surface of a solution held in a region between column banks bulges upwards out from the region between column banks
Implementation Method 3
The present disclosure relates to a display panel including an organic light-emitting element such as an organic light-emitting diode (OLED)... a first organic light-emitting layer, a second organic light-emitting layer, and a third organic light-emitting layer... the second organic light-emitting material has the same light-emission color as the light-emission color of the first organic light-emitting material
Implementation Method 4
applying a first ink containing a first organic light-emitting material above the first lower electrode, a second ink containing a second organic light-emitting material above the second lower electrode, and a third ink containing a third organic light-emitting material above the third lower electrode
Data Source
AI summary
A display panel including a substrate; first, second, and third lower electrodes; first and second column banks; first, second, and third organic light-emitting layers; and an upper electrode. When a first ink for forming the first organic light-emitting layer, a second ink for forming the second organic light-emitting layer, and a third ink for forming the third organic light-emitting layer are applied, ink-separating capability of the first column bank for separating the first ink and the second ink is lower than ink-separating capability of the second column bank for separating the second ink and the third ink, and ink-separating capability depends on: (i) a height of the first and second column banks, or (ii) liquid repellency of the first column bank against the first ink and the second ink and liquid repellency of the second column bank against the second ink and the third ink.