Pixel Electrode Contact Layout for Short-Safe Light-Emitting Displays
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Solution Overview
Problem
Display devices face issues with contact resistance between light emitting elements and pixel electrodes due to fracture surface shapes, leading to electrical short circuits and reduced light emission efficiency.
Innovation Solution
A display device design featuring a light emitting element with a specific semiconductor layer structure and an insulative film configuration, including an opening that exposes a side surface of the second semiconductor layer to reduce contact resistance and prevent electrical short circuits by aligning the light emitting element between alignment electrodes and forming pixel electrodes in contact with the end portions of the light emitting element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light emitting element is arranged in a conventional manner with complete insulative film coverage, then electrical short circuits are prevented, but contact resistance between the pixel electrode and light emitting element increases due to fracture surface shape
Solution Approach 1:
The insulative film is selectively removed from specific regions (side surfaces of the light emitting element) while maintaining coverage in other areas. This local modification allows the pixel electrode to directly contact the light emitting element in designated regions, reducing contact resistance, while preserving electrical isolation in regions where short circuits could occur.
Solution Approach 2:
The opening in the insulative film exposes the side surface of the light emitting element, creating a new contact dimension. Instead of relying solely on top-surface contact, the electrode can contact the light emitting element through the side surface, providing an additional pathway for electrical connection and reducing overall contact resistance.
2Manufacturing precision
If the insulative film is completely removed to reduce contact resistance, then electrical connection improves, but electrical short circuits between the light emitting element and pixel electrode occur
Solution Approach 1:
The insulative film removal is performed selectively in specific regions where contact is desired, while maintaining the film in regions where isolation is needed. This localized approach allows simultaneous achievement of low contact resistance in contact regions and short circuit prevention in non-contact regions.
Solution Approach 2:
The insulative film is segmented into covered and uncovered regions based on functional requirements. The opening creates distinct zones: one where the electrode contacts the light emitting element (low resistance path) and another where the film remains intact (isolation path), preventing short circuits while enabling good electrical contact.
3Manufacturing precision
If the opening in the insulative film is positioned closer to the third semiconductor layer, then contact with the second semiconductor layer is improved, but the distance to the active layer decreases potentially affecting light emission
Solution Approach 1:
The opening position is optimized to provide adequate distance from the active layer (preserving light emission) while still enabling effective contact with the second semiconductor layer. The specific positioning ensures that the electrode contact occurs in a region that is electrically effective but spatially separated from the light-generating active layer.
Data Source
AI summary
A display device may include: a substrate; a light emitting element on the substrate; a first pixel electrode on one area of the light emitting element and is electrically connected to the light emitting element; and a second pixel electrode on an other area of the light emitting element and is electrically connected to the light emitting element. The light emitting element may include: a first semiconductor layer, an active layer, and second and third semiconductor layers sequentially arranged along a first direction; and an insulative film covering outer surfaces of the first semiconductor layer, the active layer, and the second and third semiconductor layers. An opening exposing at least one side surface of the second semiconductor layer to the outside while penetrating the insulative film. The second pixel electrode may be in contact with the second semiconductor layer.