Curved Pixel Define Layer for OLED Uniformity
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Solution Overview
Problem
Conventional organic electro-luminescent devices face challenges in achieving uniformity of the thin film in the pixel area due to the straight surfaces of the pixel define layer, leading to non-uniform emission surfaces and increased process variation during thin film formation.
Innovation Solution
The organic electro-luminescent display device incorporates a pixel define layer with a predetermined curvature, where the angle between the tangent to the pixel define layer and the substrate increases with distance, forming a quadratic curve in cross-section, which reduces the inclined angle and minimizes back flow during thin film formation, thereby enhancing film uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a pixel define layer with straight surfaces is used, then the device structure is simple and easy to manufacture, but the thin film uniformity in the pixel area deteriorates
Solution Approach 1:
The pixel define layer is designed with a curved surface profile instead of straight surfaces. The cross-section of the pixel define layer forms a quadratic curve where the angle between the tangent and substrate increases with distance from the substrate, creating a predetermined curvature that eliminates back flow during thin film formation and ensures uniform film thickness across the pixel area.
2Manufacturing precision
If the pixel define layer has a curved surface with predetermined curvature, then the thin film uniformity is improved, but the device structure becomes more complex
Solution Approach 1:
The curvature of the pixel define layer is precisely controlled by adjusting formation parameters such as photoresist coating conditions, baking temperature, and etching parameters. This allows the predetermined curvature to be achieved through parameter optimization rather than complex structural design, maintaining manufacturing simplicity while ensuring thin film uniformity.
Data Source
AI summary
An organic electro-luminescent display device includes a substrate, a pixel electrode on the substrate, and a pixel define layer covering edges of the pixel electrode and having an opening to expose the pixel electrode, a surface of the pixel define layer facing the opening being bent at a predetermined curvature.