OLED Thin Film Encapsulation Tapered Edge Moisture Barrier
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Solution Overview
Problem
The existing thin film encapsulation structures for OLED display devices have issues with moisture-resistance reliability and mass-productivity due to the formation of organic barrier layers using printing methods, which do not provide sufficient coverage and are limited to active regions, leading to exposure of organic barrier layers along lead wires and terminals, compromising the bendability and reliability of the devices.
Innovation Solution
A thin film encapsulation structure is developed with a relatively thin organic barrier layer, where the organic flattening layer has an arithmetic average roughness of 50 nm or less, and is formed in a region enclosed by an inorganic barrier layer joint portion, with a tapering angle of less than 90 degrees, ensuring complete coverage and improved moisture resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a relatively thick organic barrier layer (5-20 μm) is used to ensure sufficient moisture barrier property, then the moisture-resistance reliability is improved, but the bendability of the OLED display device is limited
Solution Approach 1:
The patent applies thin film encapsulation technology using alternating inorganic and organic barrier layers to protect the OLED while maintaining flexibility. The thin film structure provides sufficient moisture barrier property without the thickness required by conventional organic barrier layers, enabling the display device to maintain bendability while achieving reliable moisture protection.
2Reliability
If a relatively thick organic barrier layer is formed by printing technology to provide moisture barrier, then the moisture protection is improved, but the mass-productivity decreases due to repeated vacuum chamber operations
Solution Approach 1:
The patent combines the formation of inorganic and organic barrier layers into a single continuous vacuum chamber process. Both layers are deposited sequentially without breaking vacuum, eliminating repeated chamber operations and significantly improving mass-productivity while maintaining the required moisture barrier property through the alternating layer structure.
Solution Approach 2:
The patent implements continuous film formation by depositing inorganic and organic barrier layers in sequence within the same vacuum chamber without interruption. This continuous process eliminates downtime for chamber evacuation and repressurization, maximizing production efficiency while ensuring consistent barrier quality throughout the encapsulation structure.
3Ease of manufacture
If printing technology is used to form the organic barrier layer, then the process is simpler, but the coverage is insufficient and the organic barrier layer is exposed along lead wires and terminals
Solution Approach 1:
The patent uses thin film deposition technology to form the organic barrier layer, which provides superior coverage compared to printing methods. The thin film process enables complete and uniform coverage including difficult-to-reach areas such as lead wires and terminals, ensuring no exposed organic barrier layer while maintaining process efficiency.
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 solution enhances the mass-productivity and moisture-resistance reliability of OLED devices by ensuring complete encapsulation and preventing moisture ingress through the organic barrier layer, while maintaining flexibility and performance.
Implementation Method 1
The organic material in the liquid drops moves on the substrate by a capillary action or a surface tension
Implementation Method 2
The organic material in the liquid drops moves on the substrate by a capillary action or a surface tension
Implementation Method 3
An organic material heated and vaporized to be mist-like is supplied onto the element substrate maintained at a temperature lower than, or equal to, room temperature. The organic material is condensed and put into liquid drops on the substrate.
Implementation Method 4
Then, the organic material is cured to form the first resin member at the border.
Data Source
AI summary
This organic EL device has a substrate, a drive circuit layer, a first inorganic protective layer, an organic planarizing layer, an organic EL element layer, and a TFE structure. The TFE structure has a first inorganic barrier layer, an organic barrier layer, and a second inorganic barrier layer. When viewed from a normal line of the substrate, the organic planarizing layer is formed within a region where the first inorganic protective layer is formed, while an organic EL element is disposed within a region where the organic planarizing layer is formed. The TFE structure has an exterior edge which intersects with a lead-out line and which is situated between an exterior edge of the organic planarizing layer and an exterior edge of the first inorganic protective layer. In a portion where the first inorganic protective layer and the first inorganic barrier layer are in direct contact with each other on the lead-out line, the first inorganic barrier layer has, in a cross-section parallel to the line width direction of the lead-out line, a lateral face that is configured to have a taper angle θ of less than 90°. The organic planarizing layer has a surface that is not more than 50 nm in arithmetic average roughness Ra.