OLED Packaging Structure Using Segmented Inorganic Layers
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Solution Overview
Problem
The existing packaging structures for OLED devices face challenges in isolating them from water and oxygen due to defects like small holes in the organic layer, caused by the large contact angle between SiNx and organic materials, leading to reduced service life and increased production costs.
Innovation Solution
A packaging structure with alternately stacked inorganic and organic layers, where the inorganic layer in contact with the OLED device includes at least two sub-films with a contact angle less than a preset angle, typically 5 degrees, using materials like SiON and SiOx to improve the affinity with the organic layer, preventing defects and enhancing isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SiNx material is used to form the inorganic layer, then the inorganic layer provides good barrier properties, but the large contact angle between SiNx and organic material causes the organic layer to fail to spread sufficiently, resulting in defects like small holes
Solution Approach 1:
The inorganic layer is segmented into multiple sub-layers with different materials (SiNx sub-layer for barrier properties, SiOx/SiON sub-layer for wettablity). This segmentation allows each sub-layer to perform its specific function, resolving the contradiction between barrier property and organic layer uniformity.
Solution Approach 2:
Different sub-layers of the inorganic layer have different local qualities: the SiNx sub-layer provides hydrophobic barrier properties, while the SiOx/SiON sub-layer provides hydrophilic surface for organic material spreading. This local quality differentiation resolves the contradiction between barrier property and wettablity.
2Manufacturing precision
If plasma or UVO treatment is applied to the inorganic layer surface, then the contact angle is reduced and organic layer spreading improves, but the production time and cost increase
Solution Approach 1:
The inorganic layer is designed with SiOx/SiON sub-layers that inherently provide good wettablity from the beginning, eliminating the need for subsequent plasma or UVO treatments. This preliminary action resolves the contradiction by built-in surface preparation.
Solution Approach 2:
The patent extracts the surface treatment step (plasma/UVO) from the production process by incorporating the wettablity function directly into the inorganic layer material composition. This removes the additional processing steps that would reduce productivity.
3Ease of manufacture
If the organic layer is formed by ink-jet printing, then the process is simple and cost-effective, but the large contact angle prevents sufficient spreading and creates defects
Solution Approach 1:
The inorganic layer has different local qualities in different sub-layers: SiNx for barrier function and SiOx/SiON for wettablity. This allows the simple ink-jet printing process to work effectively by providing a surface that promotes organic material spreading without requiring complex printing modifications.
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 allows the organic layer to spread sufficiently on the inorganic layer, effectively isolating the OLED device from water and oxygen, extending its service life without the need for expensive material replacements or surface treatments, thus improving applicability and production efficiency.
Implementation Method 1
a contact angle between a material for forming a sub-film of the at least two sub-films that contacts an organic layer and an organic material for forming the organic layer is smaller than a preset angle
Implementation Method 2
the packaging structure can isolate the OLED device from water, oxygen and other ingredients in the air
Data Source
AI summary
A packaging structure for an OLED device is provided. The packaging structure includes a plurality of films coated on an outer side of the OLED device and comprising alternately stacked inorganic layers and organic layers, wherein both a film in contact with the OLED device and a film farthest from the OLED device are inorganic layers, wherein the inorganic layer in contact with the OLED device comprises at least two sub-films sequentially stacked, and wherein a contact angle between i) a material for forming a sub-film of the at least two sub-films that contacts an organic layer and ii) an organic material for forming the organic layer is smaller than a preset angle.