Display Device Charge Generation Layer Protrusions
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Solution Overview
Problem
Display devices face challenges in improving light emitting efficiency and preventing color mixing defects between adjacent sub-pixels due to high resistance and leakage current issues.
Innovation Solution
A display device design featuring a planarization layer with protrusions, a charge generation layer continuously disposed over both pixel and non-pixel areas, and spaced pixel defining layers to increase the length of the charge generation layer, reducing resistance and blocking leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the charge generation layer area is increased to improve light emitting efficiency, then the resistance decreases, but the device structure becomes more complex
Solution Approach 1:
The planarization layer is transformed from a flat structure to one with three-dimensional protrusions. These protrusions extend vertically from the substrate, creating additional surface area for the charge generation layer without expanding the device's planar footprint. This dimensional transformation allows the charge generation layer to wrap around the protrusions, increasing its effective area and reducing resistance while maintaining a compact overall structure.
Solution Approach 2:
The planarization layer is segmented into multiple protrusions distributed across the pixel area, with each protrusion serving as an independent charge generation region. The pixel defining layer is also segmented into multiple spaced-apart layers, creating distinct zones that allow the charge generation layer to extend between them. This segmentation increases the total interface area for charge generation while maintaining structural organization.
2Reliability
If the pixel defining layers are spaced apart to increase charge generation layer length, then resistance is reduced, but color mixing prevention becomes more difficult
Solution Approach 1:
The spaced-apart pixel defining layers create localized regions where the charge generation layer can extend, but the protrusions and defining layers maintain specific spatial relationships that confine charge generation to appropriate areas. Each local region has optimized properties: the protrusions provide charge generation pathways while the pixel defining layers maintain boundaries, ensuring that charge carriers are generated and transported locally without causing color mixing between adjacent sub-pixels.
Data Source
AI summary
A display device includes a substrate including a pixel area and a non-pixel area adjacent to the pixel area, a planarization layer disposed on the substrate and including a plurality of protrusions each having a planar shape surrounding a center of the pixel area, a pixel electrode disposed on the planarization layer and overlapping the pixel area, a pixel defining layer disposed on the planarization layer, overlapping the non-pixel area, and exposing a portion of the pixel electrode, a lower light emitting layer disposed on the pixel electrode, a charge generation layer disposed on the lower light emitting layer, and an upper light emitting layer disposed on the charge generation layer.