Cathode Electrode Segmentation for OLED Moisture Resistance
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Solution Overview
Problem
Organic light emitting displays are prone to deterioration due to external factors like moisture and oxygen, leading to oxidation of the cathode electrode, which can prevent light emission, especially when a narrow bezel design increases moisture penetration.
Innovation Solution
A display apparatus design featuring a substrate with a display area and a non-display area, where the second electrode has opening areas in both regions to prevent moisture spread and oxidation, while maintaining the electrode's area to ensure effective light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the cathode electrode area is increased to ensure effective light emission, then the light emission performance is improved, but the susceptibility to moisture penetration and oxidation increases
Solution Approach 1:
The cathode electrode is divided into multiple separate electrode regions rather than forming a single continuous large-area electrode. This segmentation reduces the overall susceptibility to oxidation while maintaining sufficient light emission area, as moisture penetration at one location does not necessarily affect the entire electrode structure.
Solution Approach 2:
Different regions of the cathode electrode are designed with different properties - the central display area maintains sufficient electrode area for light emission, while the peripheral non-display area has reduced or modified electrode coverage to minimize oxidation risk. This local differentiation allows optimization of both light emission performance and oxidation resistance in different functional zones.
2Area of stationary object
If the bezel width is reduced to achieve narrow bezel design, then the display area is increased, but moisture penetration into the cathode electrode occurs more frequently
Solution Approach 1:
The cathode electrode structure is segmented to create discontinuities that act as barriers to moisture propagation. When moisture penetrates through the narrow bezel area, the segmented electrode structure prevents continuous oxidation pathways, protecting the light-emitting regions even with reduced bezel protection.
Solution Approach 2:
The electrode opening areas in the non-display region serve as intermediary zones that interrupt moisture penetration pathways. These opening areas break the continuous exposure of the cathode electrode to moisture, creating a protective effect that allows narrow bezel design without proportionally increased oxidation risk.
3Ease of manufacture
If the cathode electrode is formed as one continuous electrode with large area, then the manufacturing process is simplified, but oxidation can proceed throughout the entire electrode when moisture penetrates
Solution Approach 1:
The cathode electrode is designed with intentional openings or discontinuities in the non-display area, creating multiple separate electrode regions. This segmentation maintains relative manufacturing simplicity while fundamentally improving oxidation resistance by breaking continuous moisture pathways through the electrode structure.
Data Source
AI summary
A display apparatus in which a cathode electrode disposed in a display area is prevented from being oxidized. The display apparatus includes a substrate including a display area and a non-display area surrounding the display area, a first electrode formed on the substrate, an organic light emitting layer formed on the first electrode, and a second electrode formed on the organic light emitting layer and including at least one first opening area.