OLED Display Substrate Undercut Structure to Prevent Subpixel Leakage
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Solution Overview
Problem
In OLED display substrates, a common layer with a large thickness can lead to leakage current between adjacent subpixels due to connected portions, resulting in light leakage and compromised display quality.
Innovation Solution
A method is developed to form a pixel definition layer with an undercut on the substrate, where the common layer is broken at the undercut, preventing hole transport between subpixels by ensuring separate portions of the common layer at different pixel regions, and a cathode is formed on the substrate with a continuous surface-like structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a common layer with large thickness is used, then the common layer can provide sufficient coverage and structural support, but leakage current occurs between adjacent subpixels due to connected portions
Solution Approach 1:
The common layer is segmented into separate portions at different pixel regions by forming an undercut structure. The pixel definition layer is divided into a first portion and a second portion, with the common layer positioned between them to prevent electrical connection. This segmentation breaks the continuous path for hole transport, eliminating leakage current while maintaining sufficient common layer thickness for structural support.
2Stability of the object's composition
If the common layer is continuous, then structural integrity is maintained, but hole transport occurs between subpixels causing light leakage
Solution Approach 1:
The common layer is segmented into spatially separated portions by the undercut structure. The first portion of the common layer is positioned at a first pixel region and the second portion at a second pixel region, with no continuous connection between them. This segmentation prevents hole transport across pixel boundaries, eliminating light leakage while each portion maintains local structural integrity.
3Reliability
If an undercut structure is formed in the pixel definition layer, then the common layer can be separated at pixel boundaries, but additional manufacturing steps are required
Solution Approach 1:
The undercut structure is formed in advance during the pixel definition layer formation process, before the common layer is deposited. This preliminary action creates the necessary spatial separation structure that enables subsequent common layer portions to be naturally separated during deposition, achieving leakage current prevention through process integration rather than additional complex steps.
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 effectively prevents leakage current between subpixels, enhancing display quality by ensuring separate common layer portions and improving the formation of a continuous cathode surface.
Implementation Method 1
heating the pixel definition layer transitional pattern to melt a part of the pixel definition layer transitional pattern
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.