Flexible Cover Layer for OLED Moisture Sealing
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Solution Overview
Problem
Existing OLEDs face challenges in achieving reliable and moisture-resistant sealings between the cover and substrate, which is crucial for their long functional life, especially as they are prone to moisture penetration and require improvements for larger cell manufacturing.
Innovation Solution
The use of a flexible cover with specific flexural rigidity and a non-fixed zone around the spacer layer, combined with glass frit sealing material and controlled heat application, enhances the sealing process by ensuring mechanical contact and flexibility, thereby preventing moisture ingress and ensuring reliable electrical contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid cover is used to provide structural stability, then mechanical strength is improved, but sealing quality deteriorates due to inability to conform to height variations in sealing material
Solution Approach 1:
The patent applies a flexible cover layer with controlled flexural rigidity (0.001-0.1 Nm) that can deflect and conform to height variations in the sealing material line, ensuring continuous contact along the entire seal line while maintaining overall structural integrity through its connection to the rigid substrate and electrode layers
2Reliability
If a flexible cover is used to improve sealing contact, then sealing quality is improved, but structural stability deteriorates
Solution Approach 1:
The patent segments the cover structure into two functional parts: a flexible cover layer for sealing contact and a rigid substrate with electrode layers for structural support, allowing each segment to perform its optimized function independently
Solution Approach 2:
The patent creates a composite structure combining the flexible polymer cover layer with the rigid substrate and electrode assembly, where the flexible layer provides conformal sealing while the rigid base provides structural stability, achieving both requirements simultaneously
3Productivity
If sealing material is applied in a line process, then manufacturing efficiency is improved, but sealing uniformity deteriorates due to height variations
Solution Approach 1:
The flexible cover layer compensates for height variations in the printed sealing material line by deflecting and conforming to the actual seal line profile, ensuring continuous contact and uniform sealing quality despite manufacturing tolerances in the sealing material application process
4Stability of the object's composition
If the cover is permanently fixed to the spacer layer, then structural rigidity is improved, but flexibility for sealing contact is reduced
Solution Approach 1:
The patent segments the cover assembly into a permanently fixed rigid substrate structure and a separately attached flexible cover layer, where the flexible layer can be bonded at optimized locations to provide both structural rigidity and sealing flexibility without compromising either function
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
This approach significantly improves the moisture resistance and reliability of electrical contacts, leading to OLEDs with extended lifespan and improved performance, especially under thermal cycling conditions.
Implementation Method 1
The application of a cover layer of a flexible material appears to improve the sealing process. The inventor believes that improved sealings are obtained due to deflection of the flexible cover layer resulting in the application of mechanical forces on the seal line by the cover layer. Eventually in combination with the working of capillary forces between the cover layer and the sealing material during the sealing process a good adherence between the sealing material and the cover is obtained
Implementation Method 2
The method for attaching the cover of an electroluminescence device to its substrate... applying a closed line of sealing material... fixing the cover to the spacer layer... whereby the cover is curved around its circumference in a direction away from the device
Data Source
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AI summary
The invention relates to an OLED and its manufacture. The OLED comprises substrate (1),a first electrode layer (2),a package (3) of layers comprising organic electroluminescence material, a second electrode layer (4),a spacer layer (5) and a cover (6) being sealed to the substrate (1) via a sealing material (8). According to the invention, the cover (6) is formed as a layer of a flexible material which is permanently fixed to at least a part of the spacer layer (5). OLEDs with this feature have less moisture penetration and can be produced with less costs. Moreover, electrical contacts (11) between the cover (6) and one of the electrode layers (2, 4) are more reliable in OLEDs having this feature.