OLED Thin Film Encapsulation Protruding Structure Crack Prevention
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Solution Overview
Problem
The existing thin film encapsulation structures in OLED display devices often suffer from insufficient moisture-resistance reliability due to cracks in the inorganic material layers during the cutting process of the element substrate, which can propagate and reach the active region, compromising the device's performance.
Innovation Solution
An organic EL device with a thin film encapsulation structure that includes a first inorganic barrier layer, an organic barrier layer, and a second inorganic barrier layer, where a protruding structure with specific dimensions and tapering angles is formed to support the inorganic barrier layers and prevent cracks from reaching the active region, and a method for producing this structure by forming the layers on a substrate with a protruding structure that extends along the sides of the active region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin film encapsulation structure with inorganic barrier layers is used to protect OLED elements, then moisture resistance reliability is improved, but cracks occur in the inorganic material layers during cutting process which compromise the protection
Solution Approach 1:
The protruding structure is formed on the substrate before forming the inorganic barrier layers. This preliminary structural preparation creates a geometric feature that will later prevent crack propagation, addressing the strength issue before the moisture protection layers are even applied.
Solution Approach 2:
The protruding structure acts as an intermediary element between the substrate and the inorganic barrier layers. It provides mechanical support and crack prevention functionality while allowing the moisture-resistant inorganic layers to maintain their protective function without direct stress concentration points.
2Reliability
If the inorganic barrier layer is made thicker to prevent moisture penetration, then moisture resistance is improved, but the layer becomes more prone to cracking during cutting
Solution Approach 1:
The protruding structure creates a localized geometric feature with specific dimensions (height h1, top width w1, bottom width w2) that concentrates the crack-prevention function in a specific region. This local structural modification allows the inorganic barrier layer to maintain adequate thickness for moisture protection while the protruding structure locally manages the stress and crack propagation issues.
Solution Approach 2:
The encapsulation structure combines the inorganic barrier layer (for moisture protection) with the protruding structure (for mechanical crack prevention) into a composite system. This composite approach allows each component to fulfill its specific function - the inorganic layer provides moisture barrier property while the protruding structure provides crack resistance during cutting.
3Shape
If a thick organic barrier layer is used to flatten the substrate surface, then surface flatness is improved, but the overall device thickness increases reducing flexibility
Solution Approach 1:
The protruding structure is formed in advance on the substrate, creating a pre-configured geometric feature that enables the inorganic barrier layer to be deposited with controlled thickness. This preliminary preparation allows achieving surface flatness without requiring a thick organic barrier layer, thus maintaining device flexibility.
Solution Approach 2:
The invention changes the geometric parameters of the protruding structure (height h1, top width w1, bottom width w2) to optimize the balance between surface flatness and device thickness. By adjusting these parameters, the system achieves adequate surface flatness for proper inorganic layer formation while keeping the overall device thickness minimal to preserve flexibility.
Data Source
AI summary
An organic EL device includes an active region including a plurality of organic EL elements and a peripheral region in a region other than the active region. The organic EL device includes an element substrate including a substrate supporting the organic EL elements; and a thin film encapsulation structure covering the organic EL elements and including a first inorganic barrier layer, an organic barrier layer in contact with a top surface of the first inorganic barrier layer, and a second inorganic barrier layer in contact with the top surface of the first inorganic barrier layer and a top surface of the organic barrier layer. The peripheral region includes a first protruding structure including a portion extending along at least one side of the active region, the first protruding structure supported by the substrate, and an extending portion, of the first inorganic barrier layer, extending onto the first protruding structure.