Dual Encapsulation Layer for Organic Material Containment
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Solution Overview
Problem
In organic light emitting display devices, the fluidic organic material used for the thin encapsulation layer can overflow the substrate during fabrication, leading to uneven coverage and potential damage to the display device.
Innovation Solution
A display device design featuring a substrate with a display region and a non-display region, where dam members are placed around the display region to contain the organic material, and a dual encapsulation layer system with a first encapsulation layer of silicon oxynitride and a second encapsulation layer of silicon oxynitride or silicon oxide, where the second layer has a higher surface roughness to enhance containment and prevent overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fluidic organic material is applied to form the encapsulation layer, then the encapsulation layer can be formed to cover the pixels, but the organic material may flow toward unintended regions or overflow the substrate
Solution Approach 1:
A second encapsulation layer is introduced as an intermediary between the first encapsulation layer and the organic material. This second layer acts as a barrier that prevents the fluidic organic material from overflowing the substrate while still allowing the organic material to be deposited in the desired region. The second encapsulation layer is positioned in a region between the display region and the dam member, creating a controlled interface for the organic material deposition process.
Solution Approach 2:
The second encapsulation layer is formed in advance before the organic material is applied. This preliminary action creates a pre-defined boundary structure that guides and contains the organic material during the subsequent deposition process, preventing overflow before it can occur.
2Ease of manufacture
If a single encapsulation layer is used, then the fabrication process is simpler, but the organic material cannot be effectively contained
Solution Approach 1:
The encapsulation structure is segmented into two distinct layers: a first encapsulation layer that covers the pixels and dam members, and a second encapsulation layer that is positioned in the region between the display region and the dam member. This segmentation allows each layer to perform its specific function - the first layer provides general coverage while the second layer provides the containment barrier necessary to prevent organic material overflow.
Solution Approach 2:
The second encapsulation layer is selectively positioned only in the critical region between the display region and the dam member, where the containment function is most needed. This local quality approach ensures that the additional layer is placed precisely where it is required to prevent overflow, rather than uniformly across the entire substrate.
Data Source
AI summary
A display device includes a substrate that includes a display region and a non-display region that surrounds the display region, a plurality of pixels disposed on the display region of the substrate, a plurality of dam members disposed on the non-display region of the substrate that surround the display region, a first encapsulation layer disposed on the substrate that covers the pixels and the dam members, and a second encapsulation layer disposed on the first encapsulation layer and in a region between the display region and a dam member of the plurality of the dam members that is adjacent to the display region. A surface roughness of a top surface of the second encapsulation layer is greater than a surface roughness of a top surface of the first encapsulation layer.