Dual-Layer Gas Barrier Substrate for Flexible Displays
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Solution Overview
Problem
Flexible substrates used in display devices suffer from high temperature intolerance, poor water and oxygen resistance, and large thermal expansion coefficients, leading to accelerated aging and reduced lifespan due to incomplete blocking of water vapor and oxygen, which existing gas barrier films fail to address effectively.
Innovation Solution
A gas barrier substrate design featuring a flexible base material with a first inorganic gas barrier layer and a second inorganic gas barrier layer, where the second layer has a lower water vapor and oxygen transmission rate and higher densification than the first, allowing for improved flexibility and structural reliability while preventing gas penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of the inorganic film layer is increased to enhance gas barrier performance, then water vapor and oxygen resistance is improved, but the film layer becomes prone to cracking during bending due to stress concentration
Solution Approach 1:
The gas barrier film layer is divided into multiple inorganic sub-layers with different thicknesses and densifications rather than using a single thick layer. This segmentation allows each sub-layer to better accommodate bending stresses while collectively providing superior gas barrier performance, preventing crack formation that would occur in a single thick layer
Solution Approach 2:
Different regions of the gas barrier film layer have different densification levels and thicknesses. The inorganic sub-layers are designed with varying local properties - some regions have higher densification for better gas barrier, while others have optimized thickness for flexibility. This local quality variation allows the film to simultaneously achieve high gas barrier performance and resistance to bending-induced cracking
2Reliability
If a single layer densification barrier material is used to block water and oxygen, then gas barrier requirements are met, but the material must be carefully selected to avoid pinholes, maintain light transmittance, and prevent visible light absorption
Solution Approach 1:
The gas barrier film layer uses a composite structure of multiple inorganic sub-layers with different materials or properties rather than relying on a single material. This composite approach distributes the gas barrier function across multiple layers, reducing the risk of pinholes and defects in any single layer, while also simplifying material selection since no single material needs to perfectly satisfy all requirements
3Ease of operation
If the flexible substrate is made thinner to improve flexibility, then compliance with safety and ease of processing are improved, but water vapor and oxygen penetration increases, accelerating element aging
Solution Approach 1:
A multi-layer composite gas barrier film layer is applied to the flexible substrate, combining multiple inorganic sub-layers with different densification levels. This composite structure provides superior gas barrier performance that compensates for the reduced thickness of the flexible substrate, allowing the substrate to remain thin and flexible while maintaining adequate protection against water vapor and oxygen penetration
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-layer gas barrier substrate effectively blocks water vapor and oxygen, enhancing the product's reliability and flexibility while avoiding stress concentration-induced embrittlement, thus extending the lifespan of the display device.
Implementation Method 1
a water vapor and oxygen transmission rate (WVTR) of the second inorganic gas barrier layer is lower than a water vapor and oxygen transmission rate of the first inorganic gas barrier layer
Data Source
AI summary
A gas barrier substrate including a flexible base material, at least one first inorganic gas barrier layer and at least one second inorganic gas barrier layer is provided. The flexible base material has an upper surface. The first inorganic gas barrier layer is disposed on the flexible base material and covers the upper surface. The second inorganic gas barrier layer is disposed on the first inorganic gas barrier layer and covers the first inorganic gas barrier layer. A water vapor and oxygen transmission rate of the second inorganic gas barrier layer is lower than that of the first inorganic gas barrier layer.