Amphipathic Pixel Defining Layer for Inkjet Printed OLEDs
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Solution Overview
Problem
Existing display devices with organic electroluminescence panels face challenges in achieving high print quality of organic layers due to diffusion issues when using inkjet printing methods, as the organic materials spread beyond the intended printing area.
Innovation Solution
Incorporating a pixel defining layer with an amphipathic material that exhibits liquid-repellent properties after a plasma treatment step, where the layer has a hydrophilic group contacting the first pixel defining layer and a hydrophobic group defining the upper surface, allowing for precise placement and retention of organic layers within the defined pixel region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an organic layer is formed by an inkjet printing method, then the organic layer can be deposited, but the organic material diffuses around the printing area resulting in poor print quality
Solution Approach 1:
A pixel defining layer is introduced as an intermediary component between the substrate and the organic layer. This layer includes a liquid-repellent portion that acts as a barrier to prevent the organic material from diffusing beyond the intended printing area, thereby improving print quality while allowing the inkjet printing method to be used for organic layer formation
2Manufacturing precision
If a pixel defining layer is used to define pixel regions, then the organic layer can be confined, but the organic material still diffuses due to lack of liquid-repellent properties
Solution Approach 1:
The pixel defining layer is modified by changing its surface properties through the inclusion of a liquid-repellent portion. This parameter change creates a hydrophobic or oleophobic surface that repels the organic material, preventing diffusion and enabling effective confinement of the organic layer within the pixel region
3Reliability
If plasma treatment is applied to the pixel defining layer, then surface properties are modified, but liquid-repellent properties are not achieved without amphipathic material
Solution Approach 1:
The pixel defining layer is constructed as a composite structure that includes both a base material (such as polyimide) and a liquid-repellent material (amphipathic material). This composite structure combines the adhesion and structural properties of the base material with the liquid-repellent properties of the amphipathic material, achieving both reliable surface modification and effective material confinement
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 enhances the print quality and resolution of organic layers in organic electroluminescence display devices by preventing material diffusion and ensuring uniform deposition within the pixel region, leading to improved display performance.
Implementation Method 1
The second pixel defining layer includes an amphipathic material, and an upper surface of the second pixel defining layer is hydrophobic
Implementation Method 2
after a plasma treatment step
Data Source
AI summary
A display device includes: a substrate including a circuit layer; a first electrode on the substrate; a first pixel defining layer on the substrate and having an opening exposing an upper surface of the first electrode; a second pixel defining layer on the first pixel defining layer and comprising an amphipathic material; an organic layer on the first electrode; and a second electrode on the organic layer.