OLED Thin Film Encapsulation for Moisture and Flexibility
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Solution Overview
Problem
Current thin film encapsulation structures for OLED display devices face challenges in achieving high moisture-resistance reliability and mass-productivity while maintaining flexibility, and they can compromise the touch panel function due to issues with organic barrier layer formation and particle presence.
Innovation Solution
A thin film encapsulation structure with a composite stack body comprising a first inorganic barrier layer, a discretely distributed organic barrier layer with solid portions, and a second inorganic barrier layer, along with an organic flattening layer and a touch sensor layer, is used to enhance moisture resistance and productivity, and the organic barrier layer is formed using a photocurable resin with controlled thickness and ashing to prevent moisture ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a relatively thick organic barrier layer (5-20 μm) is used to provide sufficient water vapor barrier property and flatten the substrate surface, then moisture-resistance reliability is improved, but bendability of the OLED display device is limited
Solution Approach 1:
The organic barrier layer is divided into multiple thin layers (first organic barrier layer and second organic barrier layer) separated by an inorganic barrier layer. This segmentation allows each layer to be thinner individually while collectively providing sufficient barrier property, enabling device flexibility without compromising moisture resistance.
Solution Approach 2:
The patent uses a composite encapsulation structure combining organic barrier layers and inorganic barrier layers in an alternating stack. This composite approach leverages the complementary properties of both materials: organic layers provide flexibility and defect-free coverage, while inorganic layers provide superior moisture barrier properties and structural support.
2Reliability
If a relatively thick organic barrier layer is formed by printing technology (inkjet method, microjet method) to ensure sufficient barrier property, then moisture-resistance reliability is improved, but mass-productivity decreases due to repeated vacuum chamber operations
Solution Approach 1:
The patent combines the formation of organic barrier layers and inorganic barrier layers into a single continuous manufacturing process. The organic barrier layer is formed by printing technology in air atmosphere, followed immediately by inorganic barrier layer formation in vacuum atmosphere without removing the substrate from the processing line, eliminating repeated vacuum chamber operations and improving mass-productivity.
Solution Approach 2:
The manufacturing process is designed as a continuous operation where the organic barrier layer formation and inorganic barrier layer formation are performed sequentially in one workflow. This continuity eliminates idle time and repeated setup operations, significantly improving production efficiency while maintaining high reliability.
3Ease of manufacture
If an organic barrier layer is formed by printing method in air or nitrogen atmosphere while inorganic barrier layer is formed in vacuum, then ease of manufacture for organic layer is improved, but device complexity increases due to multiple atmosphere transitions
Solution Approach 1:
The patent employs a multi-functional manufacturing system that can operate in different atmospheres (air and vacuum) and perform multiple functions (printing organic layers and depositing inorganic layers) within a single integrated process. This universal equipment handles both organic and inorganic barrier layer formation, reducing the need for separate manufacturing lines and simplifying overall production complexity.
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 improves the mass-productivity and moisture-resistance reliability of OLED devices while preventing deterioration of the touch panel function by ensuring the organic barrier layer does not act as a route for moisture ingress and maintaining the flexibility of the OLED display device.
Implementation Method 1
the organic barrier layer is formed using a photocurable resin
Implementation Method 2
An organic material heated and vaporized to be mist-like is supplied onto an element substrate
Implementation Method 3
The organic material is condensed and put into liquid drops on the substrate
Implementation Method 4
The organic material in the liquid drops moves on the substrate by a capillary action or a surface tension
Implementation Method 5
The organic material in the liquid drops moves on the substrate by a capillary action or a surface tension
Data Source
AI summary
According to an embodiment of the invention, the organic EL device (100) comprises: an element substrate (20) having a substrate (1) and a plurality of organic EL elements (3) supported by the substrate; a thin film encapsulation structure (10) formed above the plurality of organic EL elements and having at least one compound layered body (10S) constituted by a first inorganic barrier layer (12), an organic barrier layer (14) in contact with the upper surface of the first inorganic barrier layer and having a plurality of solid sections spread out discretely, and a second inorganic barrier layer (16) in contact with the upper surface of the first inorganic barrier layer and the upper surfaces of the plurality of solid sections of the organic barrier layer; an organic planarization layer (42) provided above the thin film encapsulation structure and formed from a photosensitive resin; and a touch sensor layer (50) disposed above the organic planarization layer.