OLED Wetting Layer for Uniform PI Coating
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Solution Overview
Problem
In flexible OLED display panel manufacturing, the polyimide (PI) solution has difficulty spreading evenly on glass substrates, leading to uneven film thickness and reduced product yield and resistance due to hydrophilicity differences between PI and glass substrates.
Innovation Solution
A hydrophobic wetting layer, composed of amphiphilic surfactants like quaternary ammonium salt, sodium laurylsulfonate, and polyvinyl alcohol, is applied to the glass substrate to match its hydrophilicity with the PI material, allowing for uniform spreading and solidification of the PI layer, followed by sequential formation of transistor and emitting layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If PI solution is coated on glass substrate using conventional coating methods, then the manufacturing process is simple, but the film thickness becomes uneven due to hydrophilicity differences between PI and glass substrate
Solution Approach 1:
The patent introduces an intermediate layer between the glass substrate and PI solution to mediate the hydrophilicity mismatch. This intermediate layer has hydrophilic groups that match the glass substrate surface and hydrophobic groups that match the PI material, enabling uniform spreading of PI solution without changing the simple coating process
Solution Approach 2:
The patent modifies the surface energy parameters of the glass substrate by coating it with an intermediate layer having specific hydrophilicity characteristics. This parameter change allows the PI solution to spread uniformly on the substrate surface, resolving the thickness uniformity issue while maintaining process simplicity
2Adaptability or versatility
If PI solution is coated on glass substrate, then the flexible OLED structure is achieved, but island effusion occurs at edge regions causing reduced product yield and resistance
Solution Approach 1:
The intermediate layer acts as a mediator that prevents island effusion at edge regions by providing uniform hydrophilic-hydrophobic transition. This ensures complete and uniform coverage of PI solution across the entire substrate including edge regions, thereby improving product yield and electrical resistance
Solution Approach 2:
The patent applies the intermediate layer beforehand to prevent the harmful effect of island effusion. This preparatory measure cushions against the potential failure mode of uneven coating, ensuring reliable PI film formation across the entire substrate surface before the actual PI coating 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
This method ensures uniform film thickness of the flexible material layer, enhancing product yield and resistance of the OLED display panel by facilitating even coating and solidification of the PI layer.
Implementation Method 1
coating or spraying wetting layer material liquid configured to form the wetting layer on a surface of the glass substrate, wherein the wetting layer material liquid is hydrophobic
Implementation Method 2
heating and removing solvent of the wetting layer material liquid to form the wetting layer
Implementation Method 3
leveling and spreading the flexible material liquid on a surface of the wetting layer
Data Source
AI summary
An organic light emitting diode (OLED) display panel and a method of manufacturing same are provided. The method includes forming a wetting layer on a substrate, such that a hydrophilicity of a surface of the substrate is same as a hydrophilicity of a flexible material layer to be formed, forming the flexible material layer on the wetting layer, wherein the formed flexible material layer has a same film thickness at different positions, and sequentially forming a thin film transistor layer and an organic light emitting layer on the flexible material layer.