Display Panel Height Adjusting Layer Contact Hole
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Solution Overview
Problem
The large thickness of the planarization layer in organic EL displays increases the opening area of the contact hole, leading to higher current density and reduced lifetime of the EL layer, as well as increased voltage consumption.
Innovation Solution
A display panel with a bottom-gate thin-film transistor and a height adjusting layer below the contact hole, reducing the contact hole's depth and opening area, allowing for a larger light-emitting region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the planarization layer is made thick to achieve planarization, then the planarization effect is improved, but the opening area of the contact hole increases which reduces the light-emitting region area
Solution Approach 1:
The patent applies local quality by creating a recess portion in the planarization layer only at the contact hole region, while maintaining the overall planarization of the layer. This localized modification allows the contact hole opening area to be reduced without compromising the planarization effect in other regions, thereby resolving the contradiction between planarization quality and light-emitting region area.
2Shape
If the planarization layer thickness is increased, then planarization is improved, but the contact hole opening area increases leading to higher current density
Solution Approach 1:
By introducing a recess portion only at the contact hole region of the planarization layer, the patent locally reduces the opening area without affecting the overall planarization quality. This localized modification reduces the current density in the EL layer, thereby extending its lifetime while maintaining the planarization effect in other regions.
3Area of moving object
If the contact hole opening area is reduced to increase light-emitting region, then the light-emitting region area is improved, but the planarization layer thickness must be increased which complicates the structure
Solution Approach 1:
The patent achieves reduced contact hole opening area by creating a localized recess portion in the planarization layer, rather than increasing the overall thickness of the entire planarization layer. This localized approach reduces the light-emitting region area while avoiding the need to complicate the overall planarization layer structure, thus resolving the contradiction between light-emitting region area and device complexity.
4Area of moving object
If the contact hole opening area is reduced to increase light-emitting region, then the light-emitting region area is improved, but current density in the EL layer decreases which may affect performance
Solution Approach 1:
The patent reduces the contact hole opening area by creating a localized recess portion in the planarization layer, which increases the light-emitting region area. This localized modification optimizes the balance between light-emitting area and current density, ensuring that the EL layer receives adequate current for proper performance while maximizing the light-emitting region.
Data Source
AI summary
A display panel includes: a substrate; a bottom-gate thin-film transistor above the substrate and including a gate electrode, a first electrode, and a second electrode; an insulating layer above the thin-film transistor and including a contact hole penetrating the insulating layer in a thickness direction of the insulating layer; a pixel electrode above the insulating layer and electrically connected to the second electrode via the contact hole; and a height adjusting layer selectively located below the contact hole to allow the contact hole to have a bottom at a raised level.