Moisture-Transmission Delay Layer for OLED Edge Sealing
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Solution Overview
Problem
Existing organic light emitting display devices face issues with lifespan reduction and image quality degradation due to moisture exposure, particularly through the edges of power lines and reference lines, which can lead to dark spots and other defects.
Innovation Solution
A moisture-transmission delay layer is introduced on the exposed edges of power lines and reference lines, which overlaps with the substrate and forms a delay space between the delay layer and the protective insulation layer, effectively delaying moisture transmission and improving step coverage during the protective layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional protective insulation layer is formed directly over power lines and reference lines, then the manufacturing process is simple, but moisture transmits along the edges of the lines causing lifespan reduction and image quality degradation
Solution Approach 1:
The protective insulation layer is segmented into multiple parts: a first protective insulation layer formed only at the edges of power lines and reference lines, and a second protective insulation layer formed over the display region. This segmentation allows the first layer to block moisture transmission paths along line edges while the second layer provides general protection, resolving the contradiction by adding targeted complexity only where moisture transmission occurs.
Solution Approach 2:
The first protective insulation layer is applied locally only at the edges of power lines and reference lines where moisture transmission is most problematic, rather than uniformly across the entire substrate. This local application blocks moisture paths at critical locations while maintaining overall structural simplicity, addressing the contradiction between reliability improvement and device complexity.
2Reliability
If the protective layer is formed to completely cover power lines and reference lines, then moisture transmission is blocked, but the manufacturing precision required increases due to edge alignment complexity
Solution Approach 1:
The first protective insulation layer is formed to extend slightly beyond the edges of power lines and reference lines (excessive action), ensuring complete coverage of moisture transmission paths. This partial extension provides a safety margin that compensates for manufacturing variations without requiring precise edge alignment, resolving the contradiction between moisture protection and manufacturing precision.
3Ease of manufacture
If no additional protective layers are added, then the device structure remains simple, but moisture transmission along line edges causes dark spots and degradation
Solution Approach 1:
The first protective insulation layer is formed preliminarily over the power lines and reference lines before forming the second protective insulation layer over the display region. This preliminary action blocks moisture transmission paths at the source (line edges) before the general protective layer is applied, preventing dark spots and degradation while maintaining manufacturing simplicity through a sequential process.
Data Source
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AI summary
In an embodiment, an organic light emitting display device includes a first substrate, a display region, a pad portion, lines, and a moisture-transmission delay layer. The display region includes sub-pixels disposed on the first substrate. The pad portion is disposed on the first substrate and electrically connected to an external device. The lines are disposed between the pad portion and the display region and electrically connected to the external device, and transfer a signal or power to the external device. The moisture-transmission delay layer covers edges of the lines.