Organic Light Emitting Display Capacitor Vertical Stacking Aperture Ratio
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Solution Overview
Problem
The challenge in organic light emitting displays is to improve the aperture ratio, particularly for the bottom emission type, which is limited by the large size of the capacitor and the resulting short-circuit defect rate and process distribution issues associated with thinning the capacitor.
Innovation Solution
The solution involves arranging thin film transistors and an organic light emitting diode on one substrate and a capacitor on another substrate, with electrical connection between them, where the capacitor's lower electrode is shared with the thin film transistors and includes a spacer and dielectric layer on the second substrate, allowing for a more compact design that enhances the aperture ratio without increasing the display's thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the capacitor size is reduced to improve aperture ratio, then the aperture ratio increases, but the short-circuit defect rate and process distribution increase
Solution Approach 1:
The capacitor is moved from the first substrate to the second substrate, utilizing the third dimension (vertical stacking) to reduce the footprint on the first substrate. This dimensional transition allows the capacitor to occupy space on a different plane, effectively reducing its projected area on the active pixel region while maintaining its functional integrity and reducing short-circuit risks.
Solution Approach 2:
The display structure is segmented into two separate substrates: the first substrate contains the transistor and OLED components, while the second substrate contains the capacitor. This segmentation separates the capacitor from the thin-film transistor structure, allowing independent optimization of each component's size and reducing the likelihood of short-circuit defects between them.
2Area of moving object
If the capacitor is thinned to reduce its size, then the aperture ratio improves, but the process distribution and defect rate increase
Solution Approach 1:
By relocating the capacitor to the second substrate, the invention utilizes vertical stacking to reduce the capacitor's footprint on the first substrate without requiring thinning of the capacitor structure itself. This maintains manufacturing precision while achieving the desired reduction in occupied area.
3Ease of manufacture
If the capacitor is placed on the first substrate with thin film transistors, then electrical connection is straightforward, but the aperture ratio decreases due to larger occupied area
Solution Approach 1:
The capacitor is relocated to the second substrate, utilizing the vertical dimension to reduce the pixel area occupied by the capacitor. Electrical connection is maintained through bonding interfaces between the two substrates, where conductive structures on the second substrate connect to corresponding structures on the first substrate, preserving electrical connectivity while reducing footprint.
Solution Approach 2:
The bonding interface between the first and second substrates acts as an intermediary, enabling electrical connection between the thin-film transistors on the first substrate and the capacitor on the second substrate. This intermediary connection method allows the components to be separated spatially while maintaining functional electrical connectivity.
Data Source
AI summary
An organic light emitting display resulting in an improved aperture ratio and a manufacturing method thereof. The organic light emitting display that includes a plurality of pixels arranged between first and second substrates, each of said pixels includes a plurality of thin film transistors, an organic light emitting diode, and a capacitor. The thin film transistors and the organic light emitting diode are formed on the first substrate and the capacitor is formed on the second substrate, and the thin film transistors and the capacitor are electrically connected with each other upon the first substrate being bonded to the second substrate.