Organic Light-Emitter Bank Curvature for Ink Wetting
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Solution Overview
Problem
The existing methods for forming organic display elements using the inkjet method often result in 'insufficient wetting' issues, where the ink does not properly wet the entire area partitioned by the banks, leading to potential short circuits between the anode and cathode and degradation in display quality, particularly due to the increased risk with high liquid-repellency materials.
Innovation Solution
A light-emitter design featuring a bank with a specific cross-sectional shape where the second-order derivative of the bank's height is continuous, with an inflection point located at or greater than 0.9h0, ensuring proper wetting and contact of the functional layer with the bank's circumferential surface, thereby preventing insufficient wetting and enhancing process stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If banks are made with high liquid-repellency material to improve ink holding function, then the ability to hold ink drops is improved, but the risk of insufficient wetting increases
Solution Approach 1:
The patent applies different surface properties to different regions of the bank structure. The upper surface has high liquid-repellency for ink holding, while the circumferential surface has modified properties (through curvature design) to promote ink wetting and prevent insufficient coverage. This local differentiation resolves the contradiction between ink holding and wetting completeness.
Solution Approach 2:
The patent specifically designs the circumferential surface with a continuous second-order derivative curvature profile, creating a smooth过渡 from the upper surface to the lower surface. This curvature design ensures that ink can properly wet the circumferential surface without being repelled, while the upper surface maintains its liquid-repellent properties for effective ink holding.
2Reliability
If liquid-repellency of banks is increased to prevent ink overflow, then ink containment is improved, but insufficient wetting occurs causing short circuits
Solution Approach 1:
Different regions of the bank are given different surface characteristics. The upper surface maintains high liquid-repellency for ink containment, while the circumferential surface geometry is designed to ensure proper ink distribution and wetting, preventing short circuits between adjacent pixels.
Solution Approach 2:
The continuous curvature profile of the circumferential surface (with continuous second-order derivative) creates an optimal path for ink to wet and cover the necessary area, ensuring electrical isolation between adjacent pixels while preventing insufficient wetting that would cause short circuits.
3Manufacturing precision
If photolithography process is used to form banks with liquid-repellent resin, then bank formation precision is improved, but process complexity and risk of insufficient wetting increase
Solution Approach 1:
The patent designs the bank circumferential surface with a specific curvature characteristic (continuous second-order derivative) that can be achieved through photolithography process parameters. This geometric design simplifies the process by eliminating the need for additional surface treatment steps while ensuring proper ink wetting and preventing insufficient coverage.
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 effectively prevents insufficient wetting, ensuring stable film formation and reducing the risk of short circuits, thereby improving the quality and reliability of organic display elements.
Implementation Method 1
the risk of the insufficient wetting increases with increased liquid-repellency. The insufficient wetting can be a cause of short circuit between the anode and the cathode
Data Source
AI summary
A light-emitter with a bank having an upper surface located at a height of h0 with reference to the top surface of the base layer and a circumferential surface facing the aperture in the bank. When h denotes a height of a given point on the circumferential surface with reference to the top surface and x denotes a distance, measured in a direction along the top surface, of the given point from a boundary between the upper and circumferential surface, a second-order derivative of h with respect to x is continuous at a point corresponding to the boundary, h being smaller than h0. An inflection point of the second-order derivative is located at a height of 0.9h0 or greater with reference to the top surface, and a top surface of the functional layer is in contact with the circumferential surface at a contact point near the inflection point.