Photosensitive Pixel-Defining Layer 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 adjustments affecting luminance and driving voltage, and lack suitable alternatives to polarizing films for flexible devices.
Innovation Solution
A method for forming a pixel defining layer using a photosensitive composition, with specific pixel sizes and shapes, and a composition including inorganic and organic pigments, to enhance luminance and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the pixel size is increased to improve luminance and device lifetime, then the luminance increases and driving voltage decreases, but it becomes difficult to implement high resolution
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pixel dimensions within specific ranges (Red: 15.8-19.8 μm major axis, Green: 9.8-12.4 μm major axis, Blue: 21.3-25 μm major axis) and optimizing the aperture ratio (exceeding 25% for Red pixels). This systematic parameter optimization allows the device to achieve high luminance while maintaining high resolution, resolving the contradiction between pixel size and resolution
2Manufacturing precision
If the pixel size is decreased to improve resolution, then the resolution increases, but the luminance is lowered and driving voltage increases causing decreased lifespan
Solution Approach 1:
The patent resolves this contradiction by establishing optimal parameter ranges for pixel dimensions that simultaneously achieve high resolution and adequate luminance. The specified pixel size ranges and aperture ratio requirements ensure that resolution is maximized while luminance remains sufficient to prevent excessive driving voltages that would reduce device lifespan
3Object-affected harmful factors
If a polarizing film is used to block reflected light, then the antireflection effect is achieved, but the film is not suitable for flexible devices due to lack of bending properties
Solution Approach 1:
The patent extracts and eliminates the polarizing film from the display structure, replacing it with a pixel defining layer formed by a photosensitive composition containing colorants. This approach removes the flexibility limitation while maintaining the light-blocking function, as the pixel defining layer can be integrated into flexible substrate structures
Solution Approach 2:
The patent changes the material parameters from rigid polarizing films to photosensitive compositions that can be processed into flexible-compatible structures. The use of organic pigments and carbon black in the photosensitive composition allows for flexible device integration while achieving the desired optical properties
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 enables high-resolution displays with vivid colors and extended lifespan by optimizing pixel sizes and compositions, improving antireflection effects without the need for polarizing films.
Implementation Method 1
a 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
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.