OLED Encapsulation Layer Segmentation and Concave-Convex Adhesion
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Solution Overview
Problem
Existing organic light-emitting display apparatuses face issues with delamination of the thin film encapsulation layer, leading to increased penetration of external moisture and oxygen, which reduces the device's lifetime.
Innovation Solution
The use of a stacked encapsulation layer structure with alternating organic and inorganic layers, including silicon nitride, and the formation of concave-convex portions to increase adhesion and reduce stress, thereby preventing delamination and moisture/oxygen penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a thin film encapsulation layer is used to achieve a slim display apparatus, then the device thickness is reduced, but the encapsulation layer is prone to delamination and moisture penetration
Solution Approach 1:
The encapsulation layer is divided into multiple thin sub-layers (first encapsulation layer, second encapsulation layer, third encapsulation layer) with different material compositions and functions. Each sub-layer has a thickness of 50-200 nm, creating a segmented structure that maintains overall thinness while improving adhesion through graded material transitions and stress distribution.
Solution Approach 2:
The encapsulation system uses composite material structure combining organic materials (PMMA, polyimide) and inorganic materials (silicon oxide, silicon nitride, aluminum oxide) in alternating layers. This composite approach leverages the advantages of both material types: organic layers provide flexibility and stress relief, while inorganic layers provide barrier properties and adhesion, preventing delamination in the thin film structure.
2Length of stationary object
If the encapsulation layer is made thinner to reduce device thickness, then the device becomes slimmer, but penetration of external moisture and oxygen increases
Solution Approach 1:
The encapsulation barrier is segmented into multiple thin layers (50-200 nm each) rather than using a single thick layer. This segmentation creates multiple interfaces that block moisture and oxygen penetration paths, with the total thickness remaining thin (150-600 nm) while providing enhanced barrier performance through the multi-layer architecture.
Solution Approach 2:
The encapsulation layer uses composite material structure alternating between organic materials (PMMA, polyimide) and inorganic materials (silicon oxide, silicon nitride, aluminum oxide). The inorganic layers provide excellent moisture and oxygen barrier properties, while the organic layers provide flexibility and stress management, achieving effective protection in a thin configuration.
3Device complexity
If a single-layer encapsulation structure is used to simplify manufacturing, then the manufacturing process is simplified, but delamination occurs due to stress concentration
Solution Approach 1:
The encapsulation layer is segmented into three distinct sub-layers (first, second, and third encapsulation layers) with different material compositions and thicknesses. This segmentation distributes mechanical stress across multiple interfaces rather than concentrating it in a single layer, preventing delamination while maintaining a relatively simple manufacturing process using sequential deposition.
Solution Approach 2:
The encapsulation structure uses composite materials combining organic polymers (PMMA, polyimide) and inorganic compounds (silicon oxide, silicon nitride, aluminum oxide) in alternating layers. This composite architecture provides graded mechanical properties that reduce stress concentration at interfaces, enhancing stability and preventing delamination through material property optimization.
Data Source
AI summary
An organic light-emitting display apparatus including a substrate; a display unit which defines an active area of the substrate and includes a thin film transistor; concave-convex portions protruded from the substrate in an area outside the active area; and an encapsulation layer which encapsulates the display unit. The thin film transistor includes an active layer, a gate insulating layer on the active layer, a gate electrode, a source electrode, a drain electrode, and an interlayer insulating layer between the gate electrode and the source electrode, and between the gate electrode and the drain electrode. The concave-convex portions include portions of the gate insulating layer and the interlayer insulating layer, and the encapsulation layer covers the concave-convex portions.