Substrate Separation Structures for Uniform Ink Jet Printing
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Solution Overview
Problem
Ink jet printing of light emitting layers often results in non-uniform thickness due to the 'coffee ring effect', where the periphery of the printed layer is thicker than the center, leading to non-uniform luminescence and display quality issues.
Innovation Solution
A substrate with a printing area divided by separation structures into micro-areas with a maximum diameter of 5 μm to 10 μm, which limits the spreading of ink droplets and reduces the coffee ring effect, resulting in a uniform light emitting layer thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If ink jet printing is used to form a light emitting layer, then color directivity and pixel-specific light emission are improved, but thickness uniformity deteriorates due to the coffee ring effect
Solution Approach 1:
The printing area is divided into multiple micro-areas by introducing separation structures (ridges or grooves) that partition the ink droplet into smaller segments during drying. This segmentation prevents the formation of large-scale concentration gradients that cause the coffee ring effect, thereby achieving uniform thickness while maintaining the ink jet printing process's color directivity advantages
2Productivity
If the printing area is large, then productivity is improved, but the coffee ring effect worsens leading to non-uniform luminescence
Solution Approach 1:
The large printing area is segmented into multiple smaller micro-areas by separation structures, allowing each micro-area to dry uniformly without significant coffee ring effects. The collective arrangement of these micro-areas maintains overall productivity while ensuring luminescence homogeneity across the entire printing area
Solution Approach 2:
Different regions of the printing area are divided into micro-areas with controlled dimensions (5-10 μm circular regions), creating local quality variations that prevent the coffee ring effect in each micro-area while maintaining overall area coverage for productivity
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 use of separation structures on the substrate prevents significant coffee ring effect, achieving a light emitting layer with uniform thickness and improved luminescence homogeneity.
Implementation Method 1
a substrate having a printing area, wherein the printing area comprises a flat surface and a plurality of separation structures projecting from the flat surface, wherein the plurality of separation structures divide the printing area into a plurality of micro-areas
Data Source
AI summary
The present disclosure provides a substrate comprising a printing area, wherein the printing area comprises a flat surface and a plurality of separation structures projecting from the flat surface, wherein the plurality of separation structures divide the printing area into a plurality of micro-areas, and in each of the micro-areas, a circular region containing no separation structure has a maximum diameter between 5 μm and 10 μm. The present disclosure further provides a light emitting device comprising the substrate and a method for manufacturing the substrate.