Functional Substrate Partition for Organic EL Ink-Jet Uniformity
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Solution Overview
Problem
In organic electroluminescent devices, the 'pinning' effect during the ink-jet method of forming organic functional layers results in uneven thickness, leading to brightness spots and reduced lifespan due to increased current density at the center, making it difficult to achieve uniform display quality and extended device life.
Innovation Solution
A functional substrate with a partition structure featuring a first and second trapezoidal cross-section partition, where the lower base of the second partition is shorter than the upper base of the first, providing a liquid-repellent surface to minimize ink droplet pinning and ensure uniform thickness of the functional layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional ink-jet method is used to form organic functional layers, then the manufacturing process is simple, but the thickness uniformity deteriorates due to pinning effect
Solution Approach 1:
The partition structure is designed in advance with specific geometric parameters (trapezoidal cross-section, optimized height and width ratios) to preemptively counteract the pinning effect during ink droplet drying. The partition's inclined surface angle and dimensions are pre-calculated to ensure uniform ink distribution before the actual coating process occurs.
Solution Approach 2:
The partition dimensions are optimized by changing geometric parameters: the height is set to 1.5-3.0 μm, the top width to 20-40 μm, and the bottom width to 30-50 μm. These parameter adjustments create optimal conditions for ink droplet distribution, preventing pinning while maintaining manufacturing simplicity.
2Reliability
If the partition height is increased to prevent ink overflow, then the containment effectiveness is improved, but the pinning effect worsens due to larger inclined surface area
Solution Approach 1:
The partition height is optimized to a specific range (1.5-3.0 μm) that balances two competing requirements: it is tall enough to prevent ink overflow and ensure reliable containment, yet not so tall that the inclined surface area becomes excessive and causes severe pinning. This parameter optimization resolves the contradiction between containment effectiveness and thickness uniformity.
Solution Approach 2:
The partition employs an asymmetric trapezoidal cross-section where the top width (20-40 μm) is smaller than the bottom width (30-50 μm). This asymmetric geometry concentrates the ink containment function at the broader base while reducing the inclined surface area that causes pinning, thus resolving the contradiction between containment and uniformity.
3Manufacturing precision
If the ink droplet volume is increased to achieve desired layer thickness, then the thickness coverage is improved, but the pinning effect worsens and brightness spots increase
Solution Approach 1:
The partition dimensions are optimized to create optimal ink droplet distribution characteristics. The specific geometry (height: 1.5-3.0 μm, top width: 20-40 μm, bottom width: 30-50 μm) controls the ink spreading behavior, allowing standard ink volumes to produce uniform layers without pinning-induced thickness variations that cause brightness spots.
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 solution effectively reduces thickness variations in the organic functional layers, enhancing image display quality by minimizing brightness spots and extending the device's lifespan through improved uniformity and reduced degradation.
Implementation Method 1
The partition includes a liquid-repellent surface to minimize ink droplet pinning
Data Source
AI summary
An organic EL device includes a substrate body, a plurality of organic functional layers arranged on the substrate body in a given pattern and a partition for partitioning the plural organic functional layers. The partition includes at least a first partition part with a substantially trapezoidal cross-section provided on the substrate body and a second partition part with a substantially trapezoidal cross-section provided on the first partition part. The partition is formed so that a lower base of the cross-section of the second partition part can be shorter than an upper base of the cross-section of the first partition part.