OLED Thin Film Encapsulation via Oxidized Organic Barrier
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Solution Overview
Problem
Current thin film encapsulation structures for OLED display devices face limitations in mass-productivity, moisture-resistance reliability, and bending resistance due to the thickness of organic barrier layers and the need for vacuum processing of inorganic barrier layers.
Innovation Solution
A thin film encapsulation structure with a relatively thin organic barrier layer, where the organic barrier layer is oxidized and present on flat portions of the OLED, and the inorganic barrier layers are formed using SiN layers with controlled thickness and stress, allowing for continuous formation and improved adhesion between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick organic barrier layer (5-20 μm) is used to protect against moisture and flatten the substrate surface, then moisture resistance is improved, but bendability of the OLED display device is limited
Solution Approach 1:
The organic barrier layer is segmented 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, enabling overall flexibility while maintaining cumulative moisture barrier protection through the stacked structure.
2Reliability
If a thick organic barrier layer is formed by printing technology (inkjet method) to ensure moisture protection, then moisture resistance is improved, but mass-productivity decreases due to vacuum chamber operations
Solution Approach 1:
The formation processes of the first organic barrier layer, inorganic barrier layer, and second organic barrier layer are merged into a single continuous vacuum chamber operation. This eliminates repeated vacuum chamber entry/exit, improving mass-productivity while maintaining the multi-layer moisture barrier structure.
Solution Approach 2:
The barrier layer formation is performed as a continuous process within the vacuum chamber without interruption. The substrate remains in the vacuum chamber while sequentially forming different barrier layers, ensuring continuous useful action and eliminating productivity losses from repeated vacuum operations.
3Reliability
If multiple barrier layers are stacked alternately to achieve low WVTR (<10^-4 g/m2/day), then moisture resistance is improved, but device complexity increases
Solution Approach 1:
Different regions of the encapsulation structure have different layer compositions optimized for their specific functions. The organic barrier layers provide flexibility and surface flattening in specific regions, while the inorganic barrier layers provide superior moisture barrier properties in other regions, creating a locally optimized structure that reduces overall 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
Enhances mass-productivity, moisture-resistance reliability, and bending resistance of OLED display devices by ensuring high adhesion and uniform stress distribution across the encapsulation structure.
Implementation Method 1
An organic material heated and gasified to be mist-like is supplied onto an element substrate
Implementation Method 2
the organic material is condensed and put into liquid drops on the substrate
Implementation Method 3
Then, the organic material is cured to form the first resin member at the border
Implementation Method 4
the first resin member acts as an underlying layer for the second inorganic material layer. Therefore, the second inorganic material layer is properly formed and properly covers a side surface of the first inorganic material layer with an expected thickness
Data Source
AI summary
An organic EL display device (100) according to an embodiment of the present invention includes an organic EL element (3) formed on a flexible substrate (1) and a thin film encapsulation structure (10) formed on the organic EL element (3). The thin film encapsulation structure (10) includes a first inorganic barrier layer (12), an organic barrier layer (14) in contact with the first inorganic barrier layer (12), and a second inorganic barrier layer (16) in contact with the organic barrier layer (14). The organic barrier layer (14) is present on at least a part of a flat portion, and a surface of the organic barrier layer (14) is oxidized. A method for producing the organic EL display device (100) in an embodiment includes the step of asking the organic barrier layer.