OLED Pixel Electrode Roughness for Uniform Thin Film
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Solution Overview
Problem
Conventional organic light emitting display devices face issues with non-uniformity of the intermediate layer due to surface tension and backflow phenomena during the formation of the pixel define layer, leading to luminance non-uniformity and process deviations.
Innovation Solution
The organic light emitting display device features a pixel electrode with a rougher surface than the pixel define layer, and the side and top of the pixel define layer have different roughness levels, which reduces backflow and enhances the uniformity of the intermediate layer by controlling the thickness and tilt angle of the pixel define layer, and using a method like spin coating to form an intermediate layer by keeping organic matter on the pixel electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a pixel define layer is formed to cover the pixel electrode, then the pixel electrode is protected and defined, but surface tension and backflow phenomena cause non-uniformity in the intermediate layer formation
Solution Approach 1:
The pixel electrode surface is designed with non-uniform roughness characteristics - the top surface has a first roughness while the side surface has a second roughness that is greater than the first. This local differentiation in surface quality controls the deposition behavior of the intermediate layer, preventing backflow along the sides while ensuring uniform coverage on the top surface.
Solution Approach 2:
The pixel electrode surface is pre-treated to create specific roughness characteristics before forming the pixel define layer and intermediate layer. This preliminary surface preparation establishes controlled nucleation sites and surface energy distribution that prevent backflow phenomena during subsequent material deposition.
2Strength
If the pixel electrode surface is made rough, then adhesion and surface area are improved, but control over intermediate layer uniformity becomes difficult
Solution Approach 1:
Different regions of the pixel electrode surface are given different roughness levels: the top surface maintains lower roughness for uniform intermediate layer deposition, while the side surfaces have higher roughness to enhance adhesion and prevent backflow. This localized quality control resolves the contradiction between adhesion and uniformity.
Solution Approach 2:
The surface roughness parameter is differentiated between top and side surfaces of the pixel electrode. By controlling the roughness values in different regions, the patent optimizes both adhesion strength and intermediate layer uniformity simultaneously.
3Manufacturing precision
If the pixel define layer thickness and tilt angle are controlled, then manufacturing precision is improved, but process complexity increases
Solution Approach 1:
The pixel electrode surface is pre-configured with specific roughness characteristics before forming the pixel define layer. This preliminary action simplifies subsequent processing by establishing predetermined surface conditions that guide uniform thin film formation without requiring complex real-time control during deposition.
Solution Approach 2:
The patent controls critical parameters including pixel define layer thickness, tilt angle, and pixel electrode surface roughness. By optimizing these parameters in the design stage, the patent achieves uniform thin film formation while maintaining manageable process complexity.
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 increases the uniformity of the thin film in the sub-pixel region, reducing luminance non-uniformity and improving the manufacturing process by minimizing edge thickness variations of the intermediate layer.
Implementation Method 1
Conventional organic light emitting display devices face issues with non-uniformity of the intermediate layer due to surface tension and backflow phenomena during the formation of the pixel define layer
Data Source
AI summary
An organic light emitting display device having a uniform thin film in a sub-pixel region, and a method of manufacturing the organic light emitting display device. The organic light emitting display device includes a substrate, a pixel electrode disposed on the substrate, and a pixel define layer disposed on the substrate and exposing the pixel electrode. The surface of the pixel electrode is saw toothed or rough in shape.