Organic EL Sealing Film Grooves for Crack Resistance
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Solution Overview
Problem
The sealing film in organic electroluminescence (EL) display devices, which includes an inorganic film, is prone to cracking under stress, leading to impaired sealing ability and reliability, especially when bent or when foreign matter is present.
Innovation Solution
The display device features a sealing film with grooves between subpixels and a foreign-matter contact portion to address the issue of cracking, allowing for bending without damage and effective sealing even with foreign matter present, using a manufacturing method that includes forming an aluminum oxide film by atomic layer deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sealing film including an inorganic film is used to seal the organic EL element, then the sealing ability is improved, but the film is prone to cracking under stress when bent
Solution Approach 1:
The sealing film is divided into multiple regions by forming grooves that extend from the edge toward the center. This segmentation allows the film to flex independently in different zones, preventing stress concentration and crack propagation during bending while maintaining sealing integrity in the sealed region.
Solution Approach 2:
The sealing film has different structural properties in different regions: the sealed region maintains a continuous, intact structure for optimal sealing, while the unsealed region includes grooves that provide flexibility and stress relief. This local differentiation allows the film to simultaneously achieve both sealing ability and bend resistance.
2Reliability
If the sealing film is made rigid to maintain sealing integrity, then the sealing ability is improved, but the film cannot accommodate foreign matter on the display element
Solution Approach 1:
The sealing film transitions from a completely rigid structure to a dynamically adaptable structure by incorporating grooves. These grooves allow the film to deform and conform to the presence of foreign matter on the display element surface, enabling the sealing film to adapt to varying conditions while maintaining sealing integrity in the sealed region.
3Strength
If grooves are formed in the sealing film to prevent cracking, then the bend resistance is improved, but the film structure becomes more complex
Solution Approach 1:
Rather than adding complex reinforcement structures to the sealing film, the invention extracts material by forming grooves (removing portions of the film) to create stress relief zones. This subtractive approach achieves bend resistance with minimal added complexity, as the grooves are simple linear features that can be integrated into the existing film structure.
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 prevents cracking in the sealing film during bending and ensures reliable sealing, even with foreign matter, by distributing stress and enhancing the sealing film's flexibility and adhesion.
Implementation Method 1
the inorganic barrier film is formed by forming an aluminum oxide film by an atomic layer deposition method
Implementation Method 2
forming the foreign-matter contact portion by ashing the foreign-matter contact layer
Data Source
AI summary
An organic EL display device including: a base substrate; an organic EL element formed on the base substrate, and including a plurality of organic EL layers arranged in a matrix shape; and a sealing film formed on the organic EL element, wherein a plurality of subpixels are defined in association with the plurality of organic EL layers, and a plurality of grooves are formed in the sealing film through the interstices among the plurality of subpixels, and a foreign-matter contact portion configured to be in contact with a foreign matter existing on the organic EL element is formed in the sealing film.