Pixel Defining Layer Coating With Ultrafine Pigments for OLED Pattern Quality
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Solution Overview
Problem
Existing organic light emitting displays face issues with display reliability, lifespan, and vivid colors due to large inorganic pigment particle sizes causing pattern residues, low optical density, and high roughness, which affect luminance and visibility.
Innovation Solution
A method for preparing a pixel defining layer using a photosensitive composition with inorganic pigments of 100 nm or less, controlled to achieve an optical density of 0.8/μm to 2.0/μm and roughness of 3.0 nm or less, through application, pre-baking, exposure, developing, and post-baking processes, with specific oven temperatures and durations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If inorganic pigments with large particle size are used in the coloring pattern, then the outgas amount increases, but the pattern visibility deteriorates due to residues, low optical density, and high roughness
Solution Approach 1:
The patent changes the particle size parameter of inorganic pigments from conventional large sizes to 100 nm or less. This parameter change resolves the contradiction by maintaining high optical density and low roughness (improving pattern visibility) while still achieving sufficient outgas amount through the use of ultrafine pigment particles in the photosensitive composition
2Quantity of substance
If inorganic pigments with large particle size are used, then the outgas amount increases, but the optical density decreases and roughness increases
Solution Approach 1:
The patent applies parameter change by reducing inorganic pigment particle size to 100 nm or less, which improves optical density while maintaining outgas amount. The ultrafine particles provide better light absorption characteristics without sacrificing the gas-generating capability needed for pixel definition
3Quantity of substance
If inorganic pigments with large particle size are used, then the outgas amount increases, but the roughness becomes high
Solution Approach 1:
The patent changes the particle size parameter to 100 nm or less, which significantly reduces surface roughness while maintaining sufficient outgas amount. The ultrafine particles create a smoother coating surface that improves pattern quality and visibility
4Object-affected harmful factors
If polarizing film is used to block reflected light, then the light blocking effect is achieved, but the device cannot be made flexible due to lack of bending properties
Solution Approach 1:
The patent extracts the light blocking function from the rigid polarizing film and implements it through a flexible coloring pattern layer formed by photolithography. The coloring pattern with ultrafine inorganic pigments provides the necessary light blocking effect while allowing the display device to be flexible and bendable
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 enhances display reliability and lifetime while maintaining high optical density and reducing pattern residues, resulting in improved vivid colors and reduced roughness.
Implementation Method 1
exposure to light; developing; and post-baking of a photosensitive composition
Implementation Method 2
pre-baking; and post-baking of a photosensitive composition
Data Source
AI summary
Provided are a method for preparing a pixel defining layer comprising applying and coating, pre-baking, exposing to light, developing, and post-baking of a photosensitive composition containing a colorant having a pigment with an average particle size of 100 nm or less, wherein the coated film generated after the post-baking has an optical density of 0.8/μm to 2.0/μm, a roughness of 3.0 nm or less, and no residue; and an organic light emitting display device comprising the pixel defining layer obtained by the method which has improved display reliability and lifetime as well as vivid colors.