OLED Encapsulation Copolymer Void Reduction
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Solution Overview
Problem
The formation of voids in the organic encapsulation layer of OLED display panels due to ink droplet aggregation on hydrophilic inorganic encapsulation layers leads to water and oxygen intrusion, reducing the device's lifetime and increasing the risk of oxidation.
Innovation Solution
The use of a methyl methacrylate-N-isopropyl acrylamide copolymer solution, formed by mixing methyl methacrylate, N-isopropyl acrylamide, and a photopolymerization initiator, which is spread and cured to create a uniform organic encapsulation layer with hydrophilic and hydrophobic ends, allowing easy spreading and reducing voids, thereby enhancing the barrier properties against water and oxygen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PMMA organic encapsulation layer is used on hydrophilic inorganic encapsulation layer, then high transparency and certain water absorption are achieved, but ink droplets aggregate and form voids reducing barrier properties
Solution Approach 1:
The patent changes the chemical composition parameter of the organic encapsulation layer material by introducing N-isopropyl acrylamide groups with adjustable hydrophilicity. By controlling the mass concentration of N-isopropyl acrylamide (0.05%-20%), the ink's wetting properties are optimized to achieve uniform spreading on the hydrophilic inorganic encapsulation layer without aggregation, eliminating voids while maintaining high transparency and water absorption characteristics.
Solution Approach 2:
The patent creates a composite organic encapsulation layer material by copolymerizing methyl methacrylate (providing transparency and water absorption) with N-isopropyl acrylamide (providing hydrophilicity for uniform spreading). This composite material combines the advantages of both components: the hydrophilic N-isopropyl acrylamide groups enable uniform ink distribution on the inorganic layer, while the methyl methacrylate backbone maintains the required optical and barrier properties.
2Ease of manufacture
If ink droplets are dropped on hydrophilic inorganic encapsulation layer, then organic encapsulation layer can be formed, but droplets aggregate instead of spreading uniformly causing through-voids
Solution Approach 1:
The patent modifies the surface tension and wetting parameters of the ink by incorporating N-isopropyl acrylamide groups. This parameter change enables the ink to spontaneously spread uniformly across the hydrophilic inorganic encapsulation layer surface after droplet deposition, eliminating the aggregation problem and forming a continuous, void-free organic encapsulation layer that maintains both manufacturing ease and structural integrity.
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
This approach effectively reduces voids in the organic encapsulation layer, improves the barrier properties, and increases the lifetime of OLED devices by preventing oxidation.
Implementation Method 1
the methyl methacrylate-N-isopropyl acrylamide copolymer solution is formed by subjecting the mixed solution of methyl methacrylate, N-isopropyl acrylamide, and a photopolymerization initiator to light irradiation
Implementation Method 2
the methyl methacrylate-N-isopropyl acrylamide copolymer is distributed in such a manner that the hydrophilic end is adjacent to the inorganic encapsulation layer and the hydrophobic end is away from the inorganic encapsulation layer
Data Source
AI summary
The present application provides an organic light emitting diode (OLED) display panel and a package method thereof, the OLED display panel includes a thin film transistor layer, an OLED light emitting layer, and a thin film encapsulation layer, which are sequentially disposed on a substrate; the thin film encapsulation layer includes laminated disposing inorganic encapsulation layers and an organic encapsulation layer; wherein the material forming the organic encapsulation layer is methyl methacrylate-N-isopropyl acrylamide copolymer solution, which is spread on the surface of the inorganic encapsulation layer and after curing, used to form an organic encapsulation layer.