Pixel Defining Layer Low Permittivity Touch Defect
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Solution Overview
Problem
Existing pixel defining layers in organic light emitting display devices face challenges with high permittivity values, leading to touch defects due to the use of materials with high permittivity, which allow current flow and interfere with panel functionality.
Innovation Solution
A method involving the application and processing of a photosensitive composition with a specific post-baking step at 230° C. to 290° C. for 30 to 120 minutes, achieving an optical density of 0.8/μm to 1.3/μm and permittivity of 5.0 or less, using a colorant with inorganic and organic pigments, and a binder resin to form a stable pixel defining layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If materials with high permittivity (metal thin film or carbon black) are used as pixel defining layer, then light blocking property is improved, but touch defect occurs due to current flow through panel touch part
Solution Approach 1:
The patent changes the permittivity parameter of the pixel defining layer material from high (≥5.0) to low (≤5.0) by using organic pigments instead of metal thin films or carbon black. This parameter change maintains adequate light blocking property while eliminating the current flow issue that causes touch defects
Solution Approach 2:
The patent uses a composite material system consisting of organic pigments dispersed in a photosensitive resin matrix. This composite achieves the desired balance between light blocking property and low permittivity, resolving the contradiction between these two requirements
2Object-affected harmful factors
If pigment content is increased to improve light blocking property, then optical density is improved, but permittivity increases causing touch defect
Solution Approach 1:
The patent changes the material composition parameter from inorganic pigments (carbon black) to organic pigments, which have inherently lower permittivity. This allows achieving high optical density (0.8/μm to 1.3/μm) while maintaining permittivity at 5.0 or less, even with increased pigment content
Solution Approach 2:
The patent applies different material properties to different functional requirements: organic pigments provide both the light blocking function (optical density) and the electrical isolation function (low permittivity), whereas conventional materials could only provide one function each
3Stability of the object's composition
If post-baking temperature and time are optimized, then optical density and permittivity are stabilized, but manufacturing complexity increases
Solution Approach 1:
The patent optimizes the post-baking parameters (temperature: 230°C to 290°C, time: 30 to 120 minutes) to achieve stable permittivity (≤5.0) and optical density (0.8/μm to 1.3/μm). While this adds process complexity, the use of organic pigments inherently provides better stability compared to conventional materials
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 method reduces touch defect rates by maintaining low permittivity and high optical density, effectively preventing interference between electrodes and ensuring reliable panel performance.
Implementation Method 1
The method for preparing a pixel defining layer includes the steps of application and coating; pre-baking; exposure to light; developing; and post-baking of a photosensitive composition
Implementation Method 2
the post-baking step is performed at the oven temperature of 230° C. to 290° C. for 30 to 120 minutes
Data Source
AI summary
The present disclosure provides a method of manufacturing a pixel definition layer that reduces the touch defect rate of a panel by preventing interference between electrodes that becomes the cause of a pixel defect in the pixel definition layer. Specifically, the coating film formed by containing the colorant according to the present disclosure and treating the same at a high temperature during post-baking treatment has high optical density (OD) per thickness, and has a low permittivity constant of 5.0 or less even when the measurement Hz changes, and the change is also small.