Multi-Layer Barrier Coatings for Flexible OLED Encapsulation
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Solution Overview
Problem
Current methods for depositing high-performance coatings that provide hermetic barriers against oxygen and water vapor are costly and inefficient, particularly for flexible substrates and high-value applications like OLED displays and photovoltaic panels, as they often result in pinhole leaks, microcracking, and poor adhesion, limiting their flexibility and longevity.
Innovation Solution
A multi-layer film structure comprising alternating thin layers of silicon nitride and silicon oxynitride, deposited using a plasma-enhanced chemical vapor deposition method with varying ion bombardment and deposition rates, which enhances adhesion, flexibility, and barrier properties while reducing pinhole leaks and microcracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sputtering is used to deposit hermetic barrier layers at low temperatures, then adhesion and barrier properties are improved, but substrate heating occurs and film flexibility deteriorates
Solution Approach 1:
The patent changes the deposition parameters by using plasma-enhanced CVD instead of sputtering, allowing deposition at lower temperatures (below 100°C) while maintaining barrier properties. The process parameters including temperature, pressure, and plasma power are optimized to achieve both hermetic sealing and substrate temperature control.
Solution Approach 2:
The patent uses composite multi-layer structures combining organic and inorganic materials. The organic layers provide flexibility and adhesion, while the inorganic layers provide hermetic barrier properties. This composite approach resolves the contradiction between barrier performance and flexibility/temperature tolerance.
2Ease of manufacture
If conventional PECVD is used for deposition, then manufacturing cost is reduced, but deposition rate of high quality dielectrics at low temperatures is insufficient
Solution Approach 1:
The patent optimizes PECVD process parameters including radio frequency power, pressure, gas flow rates, and temperature to achieve both high deposition rates and high film quality. By carefully controlling these parameters, the process achieves commercial competitive deposition rates while maintaining excellent barrier properties at low temperatures.
3Reliability
If thick inorganic barrier layers are deposited to reduce pinhole leaks, then hermetic sealing is improved, but film flexibility and adhesion deteriorate
Solution Approach 1:
The patent employs alternating organic and inorganic layers where organic layers provide flexibility and stress relief, while inorganic layers provide hermetic barrier properties. This multi-layer composite structure achieves effective pinhole leakage prevention without compromising film flexibility or adhesion to the substrate.
Solution Approach 2:
The patent segments the barrier function into multiple thin alternating layers rather than using a single thick layer. The organic layers are segmented between inorganic barrier layers, creating a distributed structure that prevents crack propagation and maintains flexibility while achieving effective barrier performance.
4Strength
If plasma treatment is used to improve adhesion, then coating adhesion is enhanced, but manufacturing cost increases
Solution Approach 1:
The patent incorporates surface preparation and plasma treatment steps as preliminary actions before the main deposition process. By optimizing these preliminary steps, the process achieves excellent adhesion that eliminates the need for additional adhesion-promoting layers or treatments, thereby controlling manufacturing cost while ensuring adequate adhesion.
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 solution achieves hermetic encapsulation with low oxygen and water transmission rates, flexibility, and cost-effectiveness, enabling the production of high-yield, flexible coatings for large substrates and web-based applications, such as OLED displays and photovoltaic panels, with improved durability and performance.
Implementation Method 1
A multi-layer film structure comprising alternating thin layers of silicon nitride and silicon oxynitride, deposited using a plasma-enhanced chemical vapor deposition method
Implementation Method 2
deposited using a plasma-enhanced chemical vapor deposition method with varying ion bombardment and deposition rates, which enhances adhesion, flexibility, and barrier properties
Data Source
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AI summary
A method is disclosed for forming multi-layered structures on polymeric or other materials that provide optical functions or protect underlying layers from exposure to oxygen and water vapor. Novel devices are also disclosed that may include both multi-layered protective structures and AMOLED display, OLED lighting or photovoltaic devices. The protective multi-layer structure itself may be made by depositing successively on a substrate at least three very thin layers of material with different density or composition. In some methods for deposition of such film, the layers are deposited by varying the energy of ion bombardment per unit thickness of the film. Any layer of the structure may include one or more of the materials: silicon nitride, silicon oxide, silicon oxynitride, or metallic nitride or oxide. Specific commercial applications that benefit from this include manufacturing of photovoltaic devices or organic light emitting diode devices (OLED) including lighting and displays.