Pixel-Defining Layer Composition for High-Resolution OLED Displays
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Solution Overview
Problem
Existing organic light emitting display devices face challenges in achieving high resolution and longevity due to pixel size variations affecting luminance and driving voltage, while lacking effective alternatives to polarizing films for flexible devices.
Innovation Solution
A method is developed to form a pixel defining layer using a photosensitive composition, specifying pixel sizes and shapes for red, green, and blue pixels, along with a post-baking process to enhance resolution and reliability, using a photosensitive composition with acryl-based and cardo-based binder resins, and inorganic/organic pigments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pixel size is increased to improve luminance and reduce driving voltage, then the device lifetime and characteristics are improved, but the resolution decreases
Solution Approach 1:
The patent applies different pixel sizes to different color regions (Red: 16.2-18.5 μm, Green: 8.0-13.0 μm, Blue: 21.3-25 μm) based on their specific luminance requirements and human eye sensitivity characteristics. This local optimization allows each color to achieve optimal luminance and driving voltage characteristics while maintaining overall high resolution through the use of a photosensitive composition that enables precise pattern formation.
Solution Approach 2:
The patent utilizes a photosensitive composition containing specific binder resins (acryl-based and cardo-based) and undergoes a post-baking process at controlled temperatures to precisely control pixel dimensions. By changing the physical and chemical parameters of the composition and processing conditions, the patent achieves accurate pixel size control that simultaneously improves device reliability and maintains high resolution.
2Manufacturing precision
If the pixel size is decreased to improve resolution, then the manufacturing precision is improved, but the luminance decreases and driving voltage increases
Solution Approach 1:
The patent optimizes pixel size locally for each color region based on luminance requirements and human eye sensitivity. Green pixels are made smaller (8.0-13.0 μm) as the human eye is most sensitive to green, while Red and Blue pixels are larger to compensate for lower sensitivity, achieving both high resolution and optimal luminance efficiency.
Solution Approach 2:
The patent employs a photosensitive composition with specific resin ratios and undergoes controlled post-baking to precisely control pixel dimensions. This enables achieving the minimum required pixel size for high resolution while ensuring adequate luminance output, thereby reducing driving voltage requirements.
3Object-affected harmful factors
If a polarizing film is used to block reflected light, then the antireflection effect is achieved, but the device cannot be made flexible
Solution Approach 1:
The patent removes the polarizing film from the display structure and replaces it with a pixel defining layer formed by a photosensitive composition that provides both the light-blocking function and enables flexible device construction. This extraction of the rigid polarizing film eliminates the constraint on device flexibility.
Solution Approach 2:
The patent changes the material parameter from rigid polarizing film to a photosensitive composition that can be processed into a flexible pixel defining layer. The post-baking process at controlled temperatures (210-300°C) creates a crosslinked structure that maintains mechanical flexibility while providing the necessary optical properties for light blocking.
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 improves display reliability and lifetime by optimizing pixel sizes and shapes, achieving high resolution and vivid colors with increased luminance and reduced driving voltage.
Implementation Method 1
A method for manufacturing pixel-defining layer using a photosensitive composition... exposure to light... The method improves display reliability and lifetime by optimizing pixel sizes and shapes
Data Source
Figure 1
AI summary
An object of the present disclosure is to implement a coloring pattern with a high optical density on an electrode substrate to improve display reliability and lifetime as well as vivid colors as a display with high resolution. That is, the pixel having a size within the range according to the present disclosure can implement high resolution of a Black PDL and can manufacture a display with high luminance and long lifetime according to driving voltage and current.