Flexible OLED Buffer Layer for Stress Management
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Solution Overview
Problem
Flexible OLED displays face damage when bent or folded due to external stress, particularly affecting the insulating layers around contact holes in thin film transistors, leading to potential electrical disconnection and reduced aperture ratio.
Innovation Solution
Incorporating an organic interlayer insulating material with a tapered cross-sectional shape within contact holes, positioned within openings in the gate insulating layer, to increase the buffering force and prevent damage during bending or folding, while ensuring proper connection between electrodes and semiconductor regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the OLED display is made flexible to enable bending or folding, then adaptability is improved, but the insulating layer becomes vulnerable to external stress and damage
Solution Approach 1:
The patent applies beforehand cushioning by introducing a buffer layer between the insulating layer and the substrate. This buffer layer is specifically designed to absorb external stress during bending or folding operations, preventing the stress from being transmitted to the insulating layer and causing damage. The buffer layer acts as a protective cushion that mitigates the harmful effects of mechanical deformation on the fragile insulating layer structures.
2Manufacturing precision
If contact holes are made smaller to increase aperture ratio, then manufacturing precision is improved, but the surrounding insulating layer becomes more vulnerable to stress concentration
Solution Approach 1:
The patent applies local quality by making the buffer layer thickness non-uniform, specifically increasing the thickness at locations corresponding to contact holes compared to other areas. This localized thickening provides enhanced stress absorption and protection precisely where stress concentration occurs during bending, without unnecessarily increasing the overall device thickness or compromising aperture ratio in non-critical areas.
3Device complexity
If the insulating layer is made thinner to reduce device thickness, then device complexity is reduced, but the aperture ratio decreases due to larger contact hole requirements
Solution Approach 1:
The patent applies segmentation by dividing the protective function into two distinct components: a thin insulating layer that maintains device simplicity and a separate buffer layer that provides stress protection. This segmentation allows the insulating layer to remain thin without compromising overall device reliability, while the buffer layer specifically addresses stress protection needs, particularly around contact holes, thereby preserving aperture ratio.
Data Source
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AI summary
An organic light-emitting diode display is disclosed. In one aspect, the display includes a substrate (110) having a flexible portion configured to bend or fold, a semiconductor (130) positioned over the substrate, and a gate insulating layer (140) positioned over the semiconductor and having an opening (145, 146). The display also includes an interlayer insulating layer (160) positioned over the gate insulating layer, a portion of the interlayer insulating layer positioned within the opening. The display further includes a gate electrode (150) positioned between the gate insulating layer and the interlayer insulating layer and overlapping the semiconductor in the depth dimension of the OLED display. A source electrode (170a) and a drain electrode (170b) are positioned over the interlayer insulating layer and connected to the semiconductor.