OLED Encapsulation with Photo-Aligned Retarder
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Solution Overview
Problem
Current encapsulation structures for OLED displays are complex, thick, and heavy due to glass encapsulation, and they lack efficient anti-reflection properties, which are essential for improving the brightness and readability of OLED displays, especially in outdoor applications.
Innovation Solution
A thin encapsulation structure comprising a photo-aligned substance, a liquid crystal polymer (LCP) layer, and an inorganic layer, which provides both barrier properties against oxygen and moisture and anti-reflection properties, with the photo-aligned substance acting as a planarization layer and optical retarder, allowing for a thinner and more flexible design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass encapsulation is used, then barrier properties against oxygen and moisture are improved, but weight and thickness increase
Solution Approach 1:
The patent replaces traditional glass encapsulation with thin film encapsulation consisting of multiple alternating layers of inorganic barrier layers and organic buffer layers. The inorganic layers (such as aluminum oxide, silicon oxide, or silicon nitride) provide the necessary barrier properties against oxygen and moisture, while the organic layers (such as polyimide or acrylic resin) provide mechanical flexibility and stress relief. This thin film structure achieves effective encapsulation with significantly reduced weight and thickness compared to glass encapsulation.
2Reliability
If glass encapsulation is used, then barrier properties against oxygen and moisture are improved, but device thickness increases
Solution Approach 1:
The patent employs thin film encapsulation with inorganic barrier layers having thicknesses typically between 1-100 nm and organic buffer layers with thicknesses between 1-10 μm, creating a multi-layer structure that provides effective barrier properties while maintaining minimal overall thickness. This approach replaces thick glass encapsulation with a compact thin film stack that achieves the same protective function with dramatically reduced thickness.
Solution Approach 2:
The encapsulation structure is divided into multiple alternating inorganic and organic layers rather than using a single thick glass layer. The inorganic layers provide barrier functionality while the organic layers provide mechanical support and stress management. This segmented multi-layer architecture achieves effective encapsulation with reduced thickness compared to monolithic glass encapsulation.
3Object-affected harmful factors
If a circular polarizer is added to reduce reflection, then anti-reflection properties are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent combines the anti-reflection function with the encapsulation structure by integrating an optical retarder layer into the thin film encapsulation stack. The retarder layer is positioned between the topmost inorganic barrier layer and the external environment, working synergistically with the underlying layers to reduce reflection of ambient light. This merged structure eliminates the need for a separate circular polarizer assembly, reducing overall device complexity while maintaining effective anti-reflection properties.
Solution Approach 2:
The optical retarder layer serves multiple functions: it provides anti-reflection properties to improve outdoor visibility, contributes to the overall encapsulation barrier, and can be integrated into the existing thin film structure. By making this layer multi-functional, the patent avoids adding separate components for each function, thereby reducing device complexity and manufacturing difficulty.
4Reliability
If multiple alternating inorganic and organic layers are used, then barrier properties are improved while flexibility is maintained, but manufacturing complexity increases
Solution Approach 1:
The patent replaces traditional mechanical deposition methods with atomic layer deposition (ALD) or chemical vapor deposition (CVD) techniques for forming the inorganic barrier layers. These vapor-phase deposition methods enable precise control of layer thickness at the nanometer scale, ensure uniform coverage over large substrate areas, and facilitate the formation of high-quality thin film structures. The organic layers can be deposited using solution-based methods or sputtering, allowing for scalable manufacturing of the multi-layer encapsulation structure.
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 proposed encapsulation structure enhances the brightness and readability of OLED displays by reducing reflection and improving barrier properties, making them suitable for outdoor use while reducing weight and complexity in production.
Implementation Method 1
a layer comprising a photo-aligned substance and an LCP layer, wherein the liquid crystal orientation in the LCP layer has been created due to contact with the layer comprising a photo-aligned substance
Implementation Method 2
an LCP layer, wherein the liquid crystal orientation in the LCP layer has been created due to contact with the layer comprising a photo-aligned substance
Data Source
Figure 1a~1f
Figure 2a~2c
Figure 3a~3d
AI summary
- 32 - SUMMARY [00120] The invention relates to encapsulation structures for OLED displays, wherein the structure provides sufficient barrier properties against oxygen and moisture as well as anti-reflection properties. The structure includes a layer comprising a photo-aligned substance which in a synergistic manner controls both barrier and anti-reflection properties.