Pixel Define Layer Post-Baking Roughness Control
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Solution Overview
Problem
The existing methods for preparing pixel defining layers in organic light emitting display devices face challenges such as low adhesion of the hole transport layer (HTL) due to low surface roughness of the coloring pattern, leading to delamination and defective pixels.
Innovation Solution
A method involving the use of a photosensitive composition with a specific post-baking treatment to achieve a surface roughness of 1.48 nm to 3.0 nm, which enhances the adhesion of the HTL and minimizes delamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the surface roughness of the coloring pattern is kept low, then the smoothness of the pattern is improved, but the adhesion of the hole transport layer (HTL) deteriorates, leading to delamination and defective pixels
Solution Approach 1:
The patent applies parameter changes by modifying the post-baking treatment conditions (temperature and time) to control the surface roughness of the coloring pattern. By optimizing these parameters, the surface roughness is increased to an appropriate level that enhances HTL adhesion while maintaining pattern quality, thus resolving the contradiction between smoothness and adhesion.
2Reliability
If the post-baking treatment is performed at high temperature for extended period, then the surface roughness is increased to improve adhesion, but the energy consumption and processing time increase
Solution Approach 1:
The patent optimizes the post-baking parameters (temperature and time) to achieve the desired surface roughness with minimal energy consumption. By finding the optimal parameter combination, the patent increases surface roughness for better adhesion while avoiding excessive energy use and processing time.
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 proposed method increases the reliability and lifetime of the organic light emitting display device by improving the adhesion of the HTL and reducing the occurrence of defective pixels.
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 treatment step is preferably performed for 30 to 120 minutes at an oven temperature of 230° C. to 290° C.
Data Source
AI summary
An object of the present disclosure is to implement a coloring pattern with a constant illuminance value on an electrode substrate to thereby increase display reliability and lifetime while reducing delamination of the hole transport layer (HTL) in the post-process. That is, when the roughness of the pattern after post-baking treatment is low, it may cause delamination of the hole transport layer (HTL) and a decrease in lifetime due to defective pixels, and thus a certain roughness can be obtained by minimizing the surface flow by leaving the substrate at a high temperature during post-baking treatment according to the present disclosure.