OLED Pixel Defining Layer Ink Control via Multi-Layer Structure
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Solution Overview
Problem
Current pixel defining layers in OLED display technology face issues with uneven luminescence due to single-layer structures and high fabrication costs and complexity associated with double-layer structures, which affect the service life of devices and require multiple mask plates.
Innovation Solution
A pixel defining layer comprising a lyophilic material, a first lyophobic material with higher mass average molecular weight, and a second lyophobic material with lower mass average molecular weight, arranged in a multi-layer structure to prevent ink droplet overflow and ensure uniform spreading, using a defining solution with specific mass and fluorine content ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer pixel defining layer is used, then the fabrication process is simple, but the ink droplets form an uneven film (thick on edges, thin in middle) causing uneven luminescence
Solution Approach 1:
The pixel defining layer is divided into multiple layers with different molecular weights. The first lyophobic material (higher molecular weight) forms the bottom layer that prevents ink climbing, while the second lyophobic material (lower molecular weight) forms the top layer that maintains release properties. This segmentation resolves the contradiction by creating functional zones within the defining layer structure.
Solution Approach 2:
Different regions of the pixel defining layer are assigned different material properties. The bottom portion uses higher molecular weight material for strong ink resistance, while the top portion uses lower molecular weight material for ink release. This local differentiation of material properties enables both ink confinement and uniform film formation simultaneously.
2Manufacturing precision
If a double-layer pixel defining layer is used, then the ink droplet control is improved, but the fabrication cost and complexity increase due to requiring two sets of mask plates
Solution Approach 1:
The patent combines multiple functional materials (lyophilic material and two types of lyophobic materials with different molecular weights) into a single integrated defining solution. This merging allows all layers to be deposited simultaneously in one fabrication step, eliminating the need for multiple mask plates and sequential processing steps while maintaining precise ink droplet control.
Solution Approach 2:
The defining solution is designed to perform multiple functions simultaneously: the lyophilic material provides ink spreading control, the first lyophobic material (higher MW) prevents ink climbing, and the second lyophobic material (lower MW) ensures ink release. This multi-functional design achieves precise ink control without requiring separate structures for each function.
3Reliability
If the lyophobic layer is made thicker to prevent ink climbing, then the ink overflow is prevented, but the ink droplets cannot spread completely causing pinhole leakage
Solution Approach 1:
The patent changes the molecular weight parameter of the lyophobic materials to create different functional zones. The higher molecular weight first lyophobic material provides strong ink resistance for overflow prevention, while the lower molecular weight second lyophobic material maintains sufficient ink release capability for complete spreading. This parameter differentiation resolves the contradiction between thick barrier requirements and spreading requirements.
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 multi-layer structure prevents ink droplet climbing and ensures a flat film layer, improving luminescence uniformity and extending device service life while simplifying the fabrication process and reducing costs by eliminating the need for multiple mask plates.
Implementation Method 1
a pixel defining layer comprising a first hydrophilic layer, a first lyophobic layer, and a second lyophobic layer
Implementation Method 2
the first lyophobic layer is located on one side of the first hydrophilic layer away from the substrate; and the second lyophobic layer is located on one side of the first lyophobic layer away from the substrate
Implementation Method 3
a first hydrophilic layer, a first lyophobic layer, and a second lyophobic layer
Data Source
AI summary
The present disclosure provides a defining solution for preparing a pixel defining layer configured to define individual pixels on a substrate, comprising: a lyophilic material, a lyophobic material and an initiator, wherein the lyophobic material comprises: a first lyophobic material and a second lyophobic material, and wherein a mass average molecular weight of the first lyophobic material is greater than a mass average molecular weight of the second lyophobic material, and a mass average molecular weight of the lyophilic material is greater than the mass average molecular weight of the first lyophobic material. The present disclosure further provides a display panel, a display apparatus and a method of preparing a pixel defining layer.