Pixel Defining Layer Formation for Low-Outgas OLED Panels
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Solution Overview
Problem
Existing organic light-emitting displays face issues with high outgas levels during the manufacturing process, leading to pixel shrinkage, dark spots, and reduced lifespan due to electrode oxidation, which are not effectively addressed by current antireflection methods.
Innovation Solution
A method integrating two layers into a single process to form a pixel defining layer on an electrode substrate, involving pre-bake, exposure, development, and post-heat treatment, with specific conditions to minimize outgas generation, using a photosensitive composition containing colorants and resins to ensure vivid colors and increased display reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If coloring patterns are formed using carbon black and inorganic pigments with multiple deposition processes, then vivid colors are achieved, but outgas amount increases causing pixel shrinkage and electrode oxidation
Solution Approach 1:
The patent combines the formation of coloring patterns and pixel defining layers into a single photolithography process. The photosensitive composition contains both colorants and patterning resins, allowing simultaneous formation of colored pixel regions and black matrix structures in one exposure and development sequence, thereby reducing the number of deposition steps and minimizing outgas accumulation
Solution Approach 2:
The patent uses a composite photosensitive composition that integrates colorants (carbon black or inorganic pigments) with patterning resins in a single material system. This composite formulation enables the coloring pattern and pixel defining layer to be formed together through one photolithography process, reducing the cumulative outgas from multiple separate deposition processes
2Ease of manufacture
If multiple separate processes are used to form coloring patterns and pixel defining layers, then processing flexibility is maintained, but process time increases and panel damage accumulates
Solution Approach 1:
The patent merges two separate formation processes into one integrated photolithography process. The same exposure and development sequence that forms the coloring patterns also simultaneously creates the pixel defining layer structure, halving the process steps and reducing cumulative processing time while maintaining manufacturing flexibility through adjustable photomask designs
3Illumination intensity
If post-heat treatment is performed to remove outgas, then luminance is improved, but insufficient fume generation leads to residual outgas causing pixel shrinkage
Solution Approach 1:
The patent optimizes post-heat treatment parameters by conducting the process in a controlled atmosphere (nitrogen or oxygen environment) at elevated temperatures (100-200°C) for extended durations (1-4 hours). This parameter optimization ensures complete evaporation of solvents and decomposition of organic components, generating sufficient fume to prevent residual outgas while maintaining pixel structural integrity and preventing shrinkage
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 outgas levels to 40 ppm or less, preventing pixel shrinkage and electrode oxidation, thereby enhancing display lifespan and luminance.
Implementation Method 1
a pixel defining layer is formed on a substrate by irradiating a photosensitive composition with ultraviolet light
Implementation Method 2
a pixel defining layer is formed on a substrate by irradiating a photosensitive composition with ultraviolet light and performing post-heat treatment
Data Source
AI summary
Provided is a method for preparing a pixel defining layer which is not only to ensure vivid colors, but also to increase display reliability and lifespan by forming one or more layers through a single process of coating; pre-bake; exposure; and development, thereby implementing a coloring pattern with a low amount of outgas on an electrode substrate, wherein the method minimizes the generation of outgas in the panel state by generating sufficient fume in the post-heat treatment step in order to minimize the amount of outgas after the post-heat treatment process is completed, which may cause a decrease in luminance and a decrease in lifespan due to pixel shrinkage if the amount of outgas in a panel after post-heat treatment is 40 ppm or more, by including a colorant according to the present disclosure.