OLED Retaining Wall Segmentation for Stress Dispersion
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Solution Overview
Problem
OLED display devices face issues with film layer detachment due to stress concentration at the retaining wall in bending regions, caused by the special configuration of the retaining wall, leading to water and oxygen intrusion and device damage.
Innovation Solution
The implementation of a dual retaining wall system with buffer structures, where the first retaining wall units are spaced apart with a buffer material like acrylic or epoxy resin, and a second inorganic layer to disperse stress and prevent overflow, combined with inkjet printing for precise buffer structure formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a retaining wall is formed around the periphery of the display region to restrict the flow of the organic layer, then the organic layer can be contained within a fixed region, but stress becomes too concentrated at the retaining wall in the bending region, causing film layer detachment
Solution Approach 1:
The retaining wall is divided into multiple discrete retaining wall units spaced apart from each other, rather than forming a continuous structure. This segmentation reduces stress concentration at any single point while maintaining the overall boundary control function. The gaps between units allow stress to be distributed across multiple locations.
Solution Approach 2:
Different regions of the retaining wall structure are given different properties: the retaining wall units provide boundary definition, while the buffer structures filled in the gaps provide stress absorption and flexibility. This local differentiation allows the structure to simultaneously maintain precision and resist stress concentration.
2Ease of manufacture
If the organic layer is allowed to flow freely, then the coating process is simpler, but water and oxygen can easily intrude from the side when the organic layer flows outside the coating region, damaging the device
Solution Approach 1:
The buffer structure acts as an intermediary element between the organic layer and the external environment. It provides a transition zone that allows the organic layer to be contained while maintaining the simplicity of the coating process. The buffer material fills the gaps between retaining wall units and provides additional protection against moisture and oxygen intrusion.
3Reliability
If rigid encapsulation is used to protect metal electrodes and organic light-emitting material from water and oxygen, then device protection is improved, but the devices cannot be bent
Solution Approach 1:
The encapsulation structure uses thin-film encapsulation with multiple flexible layers (inorganic and organic films) instead of rigid encapsulation. These thin films provide protection against water and oxygen while allowing the device to be bent. The alternating inorganic and organic layers work together to provide both barrier properties and flexibility.
Solution Approach 2:
The encapsulation layer is formed as a composite structure with alternating inorganic and organic films. The inorganic layers provide water and oxygen blocking, while the organic layers provide flexibility and stress buffering. This composite structure achieves both protection and bendability simultaneously.
Data Source
AI summary
The invention relates to an organic light-emitting diode (OLED) display device and a manufacturing method thereof. In the invention, a first retaining wall corresponding to a bending region is configured to include first retaining wall units spaced apart from each other, and a first buffer structure is formed in a gap provided between the first retaining wall units and is alternately connected to a left side and a right side of the first retaining wall units. This can prevent excessive stress concentration on the retaining wall in the bending region due to its special configuration, which causes a phenomenon of film layer detachment. Therefore, a failure of the OLED display device is prevented.