Flexible OLED Encapsulation Using ALD Inorganic Layers
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Solution Overview
Problem
Existing OLED display devices face damage from moisture and mechanical stress during high temperature, high humidity, and flexible operations, leading to reduced displaying quality and lifetime due to incomplete coverage of inorganic layers and increased stress on encapsulation films.
Innovation Solution
The OLED display device employs a multi-layered encapsulation structure with a first inorganic layer formed by atomic layer deposition (ALD) for excellent step-coverage, followed by a second inorganic layer and organic layers to prevent moisture penetration and absorb mechanical stress, while maintaining a thin profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glass encapsulation substrate is used to protect the light emitting diode from moisture, then the light emitting diode is protected from moisture damage, but the device becomes rigid and vulnerable to damage during folding, bending, or rolling operations
Solution Approach 1:
The patent replaces the rigid glass encapsulation substrate with flexible encapsulation films comprising multiple alternating inorganic and organic layers. The inorganic layers (such as silicon oxide, silicon nitride, or aluminum oxide) provide moisture barrier protection, while the organic layers (such as acrylic or epoxy-based materials) provide flexibility and stress absorption. This multi-layer flexible encapsulation structure enables the OLED device to be folded, bent, or rolled without damage while maintaining protection from moisture penetration.
2Ease of manufacture
If an inorganic layer is formed using conventional PECVD to reduce manufacturing complexity, then the manufacturing process is simpler, but the inorganic layer has poor step-coverage and leaves gaps at edges and corners
Solution Approach 1:
The patent segments the encapsulation structure into multiple alternating inorganic and organic layers. The inorganic layers are formed using ALD to provide excellent step-coverage and gap-free protection at edges and corners, while the organic layers are formed using PECVD to provide flexibility and stress absorption. This segmentation allows each layer type to compensate for the weaknesses of the other, achieving both complete coverage and flexibility.
Solution Approach 2:
The patent employs a composite multi-layer encapsulation structure combining inorganic materials (such as silicon oxide, silicon nitride, aluminum oxide) and organic materials (such as acrylic or epoxy-based polymers). The inorganic layers provide superior moisture barrier properties with excellent step-coverage, while the organic layers provide flexibility and mechanical stress absorption. This composite structure achieves both complete edge coverage and flexibility for formable displays.
3Reliability
If the encapsulation film thickness is increased to improve moisture protection, then the moisture barrier is enhanced, but the device thickness increases and flexibility is reduced
Solution Approach 1:
The patent uses a composite multi-layer encapsulation structure where thin inorganic layers (each typically 5-50 nm thick) and thin organic layers (each typically 50-200 nm thick) are alternately stacked. This composite structure provides effective moisture barrier protection through the multiple inorganic layers while maintaining overall thinness and flexibility. The alternating structure allows each thin layer to contribute to moisture protection without requiring excessive total thickness.
Solution Approach 2:
The patent transitions from a single thick encapsulation layer to a multi-layer stacked structure, effectively using the vertical dimension to enhance protection. By stacking multiple thin inorganic and organic layers alternately, the structure provides comprehensive moisture barrier coverage through multiple interfaces while maintaining overall thinness. This dimensional approach allows enhanced protection without proportionally increasing total thickness.
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 prevents moisture damage and enhances the flexibility and longevity of OLED display devices without increasing the encapsulation film thickness, thereby improving displaying quality and lifetime.
Implementation Method 1
At least part of a first inorganic layer is formed on the plurality of pixel regions using atomic layer deposition (ALD)
Implementation Method 2
A first inorganic layer is formed on the plurality of pixel regions using atomic layer deposition (ALD) or plasma-enhanced chemical vapor deposition (PECVD). A first organic layer is formed and a second inorganic layer is formed using PECVD.
Data Source
AI summary
Embodiments relate to a method of forming an organic light emitting diode (OLED) display device. A first inorganic layer, a first organic layer, and a second inorganic layer are formed on pixel regions of an OLED display device. At least part of a first inorganic layer is formed using atomic layer deposition (ALD), such that the first inorganic layer completely covers particles generated on the OLED. Embodiments also relate to an OLED display device with pixel regions, each pixel region including an OLED, a bank layer across a boundary between adjacent pixel regions, and a first inorganic layer on at least a portion of the OLED and the bank layer. The first inorganic layer includes a first inorganic sub-layer and a second inorganic sub-layer.