Flexible OLED Pixel Circuit Layout Against Micro-Crack Disconnection
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Solution Overview
Problem
Display devices, particularly flexible OLED displays, face challenges in maintaining display quality while minimizing the impact of external factors such as bending or mechanical stress, which can lead to electrical disconnections and bright spots due to micro-cracks in the semiconductor layers.
Innovation Solution
The implementation of a specific structure including multiple transistors, gate conductive layers, and connection electrodes with protrusions and openings, along with a connection metal conductive layer using materials like gold, silver, or copper, to maintain electrical connections even if micro-cracks occur, and an insulating film to isolate pixel circuit areas, reducing the propagation of cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a flexible substrate is used to enable bending, then adaptability is improved, but reliability deteriorates due to micro-cracks and electrical disconnections
Solution Approach 1:
The connection electrode is divided into multiple regions ((1-1)-th region, (1-2)-th region, (1-3)-th region) that can independently maintain electrical connection. The (1-2)-th and (1-3)-th regions protrude and are spaced apart, creating redundant connection paths that can withstand bending stresses without simultaneous failure.
Solution Approach 2:
The insulating film with valley structure is designed beforehand to prevent crack propagation. The valley surrounding the first semiconductor layer acts as a barrier that stops cracks from spreading laterally, cushioning against the harmful effects of mechanical stress before they can cause electrical disconnection.
2Device complexity
If the connection electrode structure is simplified, then device complexity is reduced, but reliability deteriorates due to increased susceptibility to micro-cracks
Solution Approach 1:
The connection electrode has different structural characteristics in different regions. The (1-2)-th and (1-3)-th regions have protruding structures with spacing, while the (1-1)-th region connects to the first transistor. This local structural variation provides enhanced crack resistance where needed without unnecessarily complicating the entire electrode structure.
3Reliability
If the insulating film structure is enhanced to prevent crack propagation, then reliability is improved, but device complexity increases
Solution Approach 1:
The insulating film is segmented to form valleys that surround the first semiconductor layer. This segmentation creates natural barriers that prevent crack propagation while maintaining a relatively simple overall structure. The valleys are formed by removing or thinning portions of the insulating film rather than adding complex structures.
Data Source
AI summary
A display device includes a substrate, a first semiconductor layer, and including first and second transistors, first and second gate conductive layers above the first semiconductor layer, a second semiconductor layer above the second gate conductive layer, and including a third transistor, a third gate conductive layer above the second semiconductor layer, an insulating film defining a valley surrounding the first semiconductor layer, the first gate conductive layer, the second gate conductive layer, the second semiconductor layer, and the third gate conductive layer, a connection metal conductive layer above the insulating film, and including a first connection electrode electrically connecting the first and third transistors, the first connection electrode including a (1-1)-th region overlapping the first transistor, and a (1-2)-th region and a (1-3)-th region overlapping the third transistor and connected to the third transistor, and first and second data conductive layers above the connection metal conductive layer.