Pixel Define Layer Composition for Low-Outgassing OLED Displays
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Solution Overview
Problem
Conventional methods for forming a pixel defining layer in organic light emitting displays suffer from high outgassing, leading to issues such as pixel shrinkage, dark spots, and reduced lifetime and luminance, particularly due to the use of organic pigments as colorants.
Innovation Solution
A method involving the use of a photosensitive composition for preparing a pixel defining layer, including specific binder resins and colorants, with controlled post-baking conditions to minimize outgassing, specifically at temperatures between 210° C. to 300° C. for 30 to 120 minutes, resulting in reduced outgassing below 15 ppm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If coloring patterns with organic pigments are used to achieve vivid colors, then color quality is improved, but outgassing increases causing pixel shrinkage and reduced lifetime
Solution Approach 1:
The patent changes the chemical composition parameters of the photosensitive composition by replacing conventional organic pigment-based colorants with inorganic pigment-based colorants. This parameter change fundamentally alters the outgassing characteristics while maintaining color performance, thereby resolving the contradiction between color vividness and display lifetime.
2Ease of manufacture
If conventional post-baking is performed to complete the photosensitive composition, then processing is completed, but outgassing exceeds acceptable levels causing pixel defects
Solution Approach 1:
The patent converts the potentially harmful outgassing effect into a beneficial process by carefully controlling the post-baking conditions. The controlled thermal treatment activates the inorganic pigments and completes the photosensitive composition while generating minimal harmful outgas, transforming what would be a harmful process into a beneficial one that ensures both processing completion and low outgassing.
3Reliability
If inorganic pigments are used as colorants, then outgassing is reduced, but color vividness may be compromised
Solution Approach 1:
The patent employs composite materials by formulating a photosensitive composition that integrates inorganic pigments with specifically selected binder resins and curing agents. This composite approach allows the inorganic pigments to provide low outgassing while the organic components of the composite formulation enhance and maintain color vividness, thereby resolving the contradiction between outgassing control and color quality.
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 significantly reduces outgassing, enhancing the reliability and lifetime of the display by minimizing pixel shrinkage and maintaining vivid colors, thereby improving the overall performance of the organic light emitting display device.
Implementation Method 1
exposure to light; developing; and post-baking of a photosensitive composition
Implementation Method 2
the post-baking step is performed at an oven temperature of 210° C. to 300° C. for 30 to 120 minutes; the amount of outgas generated after the post-baking step is 15 ppm or less
Data Source
AI summary
An object of the present disclosure is to implement a coloring pattern with a low amount of outgas on an electrode substrate to thereby increase reliability and lifetime of display as well as vivid colors of the same. That is, considering that when the amount of outgas in the panel after post-baking is 15 ppm or more, it may cause a reduction in luminance and lifetime due to pixel shrinkage, in order to minimize the amount of outgas after completion of the post-baking process, the generation of outgas in the panel state is minimized by generating sufficient fume in the post-baking step by way of including a colorant according to the present disclosure.