OLED Display Substrate Undercut Structure for Subpixel Leakage Isolation
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Solution Overview
Problem
In OLED display substrates, the common layer can cause leakage current between adjacent subpixels due to connections between different pixel regions, leading to light leakage and decreased display quality.
Innovation Solution
A method for manufacturing a display substrate involves forming a pixel definition layer transitional pattern with an undercut on a base substrate, breaking the common layer at the undercut, removing the undercut to form a pixel definition layer pattern, and forming a cathode on the substrate. This ensures that the common layer is broken between pixel regions, preventing hole transport between subpixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a common layer with large thickness is used, then the display substrate can be manufactured with simpler structure, but leakage current occurs between adjacent subpixels causing light leakage
Solution Approach 1:
The common layer is segmented into separate portions at different pixel regions by utilizing the undercut structure of the pixel definition layer. This segmentation prevents hole transport between adjacent subpixels while maintaining manufacturing simplicity, as the segmented structure is formed automatically during the standard manufacturing process without requiring additional steps.
Solution Approach 2:
The undercut structure serves as an intermediary element between the pixel definition layer and the common layer. It acts as a barrier that prevents the common layer from forming continuous connections between adjacent subpixels, thereby eliminating leakage current paths while maintaining the overall structural integrity and manufacturing simplicity of the display substrate.
2Reliability
If the common layer is broken at the undercut to prevent leakage current, then display quality improves, but the cathode formation becomes more difficult
Solution Approach 1:
The undercut structure is formed in advance during the pixel definition layer fabrication process, creating a pre-prepared barrier structure before cathode deposition. This preliminary action ensures that when the common layer is deposited, it automatically breaks at the undercut, and subsequently, the cathode can be formed continuously over the segmented common layer without requiring additional processing steps.
3Reliability
If a thin pixel definition layer is used to reduce light leakage, then display quality improves, but the undercut formation becomes more difficult
Solution Approach 1:
The thickness parameter of the pixel definition layer is optimized to a specific range that enables effective undercut formation. By controlling the thickness parameter, the pixel definition layer can provide sufficient undercut depth to break the common layer and prevent leakage current, while maintaining manufacturability of the undercut structure through standard etching processes.
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
The solution effectively prevents leakage current between adjacent subpixels by ensuring that the common layer is broken between pixel regions, thereby improving the display quality of OLED display devices by reducing light leakage and crosstalk.
Implementation Method 1
heating the pixel definition layer transitional pattern to melt a part of the pixel definition layer transitional pattern, in such a manner to remove the undercut and form a gentle slope
Data Source
AI summary
A display substrate, a manufacturing method thereof, and a display device. The method includes: forming a pixel definition layer transitional pattern on a base substrate, the pixel definition layer transitional pattern being provided at a lateral surface with an undercut; forming a common layer, which is broken at the undercut, on the base substrate; removing the undercut to obtain a pattern of a pixel definition layer; and forming a cathode on the base substrate.