Flexible OLED Encapsulation with Metal Layer for Crack Resistance
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Solution Overview
Problem
Flexible OLED display devices face damage and reduced lifespan due to moisture penetration and stress concentration in encapsulation films during folding, bending, or rolling, leading to cracks and decreased displaying quality.
Innovation Solution
A multi-layered encapsulation film structure with a metal layer of low stiffness materials like silver, gold, or palladium alloys is applied on the flexible substrate, particularly in bending regions, to prevent moisture penetration and reduce stress, thereby preventing cracks in the encapsulation film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glass encapsulation substrate is used to protect the light emitting diode from moisture, then the light emitting diode is protected from moisture penetration, but the device becomes rigid and cannot be folded or bent
Solution Approach 1:
The patent replaces the rigid glass encapsulation substrate with a flexible encapsulation film comprising multiple thin layers (first encapsulation layer, second encapsulation layer, and third encapsulation layer). This flexible film structure provides moisture protection while allowing the display device to be folded or bent, directly resolving the contradiction between protection and flexibility.
2Adaptability or versatility
If a flexible encapsulation film is used to enable folding and bending, then the device becomes flexible and foldable, but the encapsulation film develops cracks during repeated folding leading to light emitting diode damage
Solution Approach 1:
The patent employs a composite encapsulation structure with multiple layers having different properties. The first encapsulation layer provides baseline protection, the second encapsulation layer (with higher elasticity modulus) provides enhanced crack resistance in bending regions, and the third encapsulation layer provides additional protection. This composite structure enables both flexibility and crack resistance.
Solution Approach 2:
The patent applies the second encapsulation layer specifically in the bending region where cracks are most likely to occur during folding. This localized reinforcement with higher elasticity modulus material provides targeted crack resistance where needed most, while maintaining overall device flexibility.
3Shape
If the encapsulation film is made thinner to improve flexibility, then the device can be folded with a smaller curvature radius, but the encapsulation film becomes more susceptible to cracks and moisture penetration
Solution Approach 1:
The multi-layer composite encapsulation structure allows the film to be thin enough for small curvature radius folding while maintaining crack resistance through the distributed layer structure. The second encapsulation layer with higher elasticity modulus provides reinforcement without significantly increasing thickness.
Solution Approach 2:
Instead of increasing the thickness of a single encapsulation layer, the patent adds a third dimension to the structure by stacking multiple thin layers. This multi-layer approach provides enhanced mechanical strength and crack resistance while maintaining overall thinness and flexibility for small curvature radius folding.
Data Source
AI summary
Embodiments relate to a flexible organic light emitting diode (OLED) display device and a method for manufacturing the flexible OLED display device. The display device includes a multi-layered encapsulation film coving pixel regions of the display device, and a metal layer on or within at least a portion of the encapsulation film, the portion in a bending region of the flexible substrate. The multi-layered encapsulation film includes at least a first inorganic layer, an organic layer, and a second inorganic layer. The metal layer is formed in the bending region such that the stress generated in the encapsulation film by folding, bending, or rolling operations in the bending region is reduced by the metal layer. The metal layer prevents generation of cracks in the encapsulation film and thus, prevents moisture penetration into the display area of the display device.