Shared Contact Hole for OLED Anode Connection
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Solution Overview
Problem
In organic light emitting display devices, the reduction in pixel size leads to a decrease in the emissive area ratio, resulting in a shortened lifetime of the organic light emitting layer and potential turn-on defects due to disconnection of the anode electrode at the side surface of the source or drain electrode, caused by the step change in height of the contact hole.
Innovation Solution
The implementation of a shared contact hole that connects multiple pixels' drain electrodes to a single anode electrode, preventing the reduction of the emissive area and ensuring continuous electrode connection through simultaneous etching of the anode and drain electrodes, thereby maintaining the organic light emitting layer's integrity and preventing turn-on defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel size is reduced to achieve high resolution, then the resolution is improved, but the emissive area ratio decreases and the lifetime of the organic light emitting layer is shortened
Solution Approach 1:
Multiple pixels share a common contact hole structure, merging what would traditionally be separate contact holes for each pixel. This reduces the total contact hole area relative to pixel area, thereby increasing the emissive area ratio while maintaining high resolution display capabilities
Solution Approach 2:
The shared contact hole structure serves multiple pixels simultaneously, performing the function of electrical connection for multiple pixels through a single structural element. This multi-functional approach reduces the overall footprint of non-emissive areas
2Length of moving object
If the contact hole size is reduced to maintain pixel size, then the pixel size is maintained, but the anode electrode becomes disconnected at the side surface of the source or drain electrode due to step change in height
Solution Approach 1:
The anode electrode is formed to extend beyond the contact hole opening before the contact hole is etched. This preliminary positioning ensures that even after etching creates a step change in height, the anode electrode maintains continuous connection to the drain electrode without disconnection at the side surfaces
Solution Approach 2:
The anode electrode is positioned in a planar dimension that extends beyond the vertical boundaries of the contact hole. By utilizing this lateral extension approach rather than attempting to bridge the vertical step directly, continuous electrical connection is achieved while accommodating the step change in height
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
Disclosed are a light emitting display device and a method of manufacturing the same, which prevent the lifetime of a light emitting layer from being shortened and prevent occurrence of a turn-on defect. The light emitting display device includes a plurality of pixels each including a transistor having a gate electrode, an active layer overlapping the gate electrode, a source electrode connected to one side of the active layer, and a drain electrode connected to another side of the active layer. The pixels further include a light emitting device having a first electrode, a light emitting layer disposed on the first electrode, and a second electrode disposed on the light emitting layer. The light emitting display device includes a contact hole, and the first electrodes of at least two of the plurality of pixels are positioned on and electrically connected to respective source electrodes or to respective drain electrodes in the contact hole.