Flexible Light-Emitting Device Dual-Bonding Seal Against Moisture
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Solution Overview
Problem
Organic electroluminescent (EL) elements in light-emitting devices are susceptible to degradation due to the entry of impurities such as moisture and oxygen, which reduces their lifetime and reliability.
Innovation Solution
A dual-bonding layer structure is employed, where a flexible substrate is sealed by two bonding layers, with one having a higher gas barrier property than the other, to prevent impurity ingress, while maintaining high light transmission and minimizing volume reduction during curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single bonding layer is used to seal the organic EL element, then the device structure is simple, but impurities such as moisture and oxygen can enter and degrade the element
Solution Approach 1:
The bonding layer is divided into multiple layers with different functions: a first bonding layer for sealing and a second bonding layer with higher gas barrier properties for enhanced protection. This segmentation allows each layer to perform its specific function optimally while together providing comprehensive protection against impurity entry.
Solution Approach 2:
The patent uses composite bonding layer structures combining materials with different gas barrier properties. The first bonding layer may use materials like acrylic or epoxy resin, while the second bonding layer uses materials with superior gas barrier properties, creating a composite structure that balances sealing effectiveness with impurity protection.
2Reliability
If a bonding layer with high gas barrier property is used, then impurity entry is prevented, but light transmission is reduced
Solution Approach 1:
Different regions of the bonding layer structure have different properties optimized for their specific functions. The first bonding layer prioritizes light transmission while providing basic sealing, whereas the second bonding layer prioritizes gas barrier properties in regions where light transmission is less critical, achieving local optimization of both properties.
Solution Approach 2:
The solution moves from a single-layer approach to a multi-layer approach, adding a vertical dimension to the bonding layer structure. This allows light to pass through the first bonding layer while the second bonding layer provides gas barrier protection, effectively separating the optical and protective functions across different layers.
3Reliability
If a thick bonding layer is used to ensure sealing, then impurity protection is improved, but volume reduction during curing increases
Solution Approach 1:
The total bonding layer thickness is segmented into multiple thinner layers rather than using one thick layer. This segmentation reduces the overall volume reduction during curing while maintaining effective sealing, as each thinner layer experiences less shrinkage during the curing process.
Solution Approach 2:
The patent employs composite bonding layer materials where the first bonding layer uses materials with lower shrinkage during curing, and the second bonding layer provides additional sealing. This composite approach ensures effective sealing while minimizing total volume reduction during the curing process.
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 dual-bonding layer structure enhances the reliability and longevity of the light-emitting device by effectively blocking moisture and oxygen, thereby suppressing luminance degradation and increasing light extraction efficiency.
Implementation Method 1
The second bonding layer has a higher gas barrier property than the first bonding layer
Implementation Method 2
a light-emitting element which includes a layer containing a light-emitting organic compound
Data Source
AI summary
A highly reliable flexible light-emitting device is provided. The light-emitting device includes a first flexible substrate, a second flexible substrate, a light-emitting element between the first flexible substrate and the second flexible substrate, a first bonding layer; and a second bonding layer in a frame shape surrounding the first bonding layer. The first bonding layer and the second bonding layer are between the second flexible substrate and the light-emitting element. The light-emitting element includes layer containing a light-emitting organic compound between the pair of electrodes. The second bonding layer has a higher gas barrier property than the first bonding layer.