Stretchable OLED Island-Bridge Layout to Prevent Pixel and Wire Damage
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Solution Overview
Problem
Stretchable OLED displays face challenges as light emitting elements on stretchable substrates can be damaged when the substrate is extended or contracted, and wires can become shorted due to stress.
Innovation Solution
The design includes a substrate with defined islands and bridges, where the islands and bridges are cutout portions that maintain their shape even when the substrate is stretched, and a wire is placed in each bridge to connect pixels, with an organic insulating layer covering the bridges and a specific arrangement of inorganic insulating layers to minimize stress on the wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If light emitting elements are formed on a stretchable substrate, then the display can be bent or folded, but the light emitting elements may be damaged when the substrate is stretched
Solution Approach 1:
The substrate is divided into multiple islands separated by cutout portions, with bridges connecting the islands. This segmentation allows the substrate to stretch without damaging the light emitting elements formed on the islands, as the cutout portions accommodate the mechanical stress during stretching and contracting.
Solution Approach 2:
Different regions of the substrate have different structural properties: the islands maintain a solid structure to support light emitting elements, while the cutout portions and bridges are designed to accommodate stretching. This local differentiation allows the display to be stretchable while protecting the light emitting elements.
2Ease of operation
If wires are placed on a stretchable substrate to connect pixels, then electrical connection is achieved, but the wires may become shorted due to stress during extension or contraction
Solution Approach 1:
Insulating layers are formed beforehand to cover the bridges and wires before the substrate is stretched. These insulating layers act as a protective cushion that prevents wire shorting even when the substrate undergoes extension or contraction, accommodating the mechanical stress without compromising electrical insulation.
Solution Approach 2:
The insulating layers serve as an intermediary between the wires and the mechanical stress of substrate stretching. They transfer and distribute the stress away from the wires, preventing direct contact between wires during substrate deformation and thus avoiding short circuits.
3Adaptability or versatility
If the substrate is repeatedly extended or contracted, then the display achieves flexibility, but the light emitting elements and wires are subjected to cumulative stress
Solution Approach 1:
The segmented island-bridge structure with cutout portions allows the substrate to repeatedly extend and contract without cumulative damage. The cutout portions act as stress relief zones that accommodate repeated deformation, preventing fatigue failure of the light emitting elements on the islands.
Solution Approach 2:
Multiple insulating layers are formed beforehand to provide cumulative protection against repeated stress cycles. These layers absorb and distribute the mechanical stress from repeated extension and contraction, preventing progressive damage to the wires and maintaining structural integrity over time.
Data Source
AI summary
A display device includes: a substrate on which a plurality of islands and a plurality of bridges connecting the plurality of islands to each other are defined; a plurality of pixels disposed in each of the plurality of islands; and a wire disposed in each of the plurality of bridges and connected to the plurality of pixels, where the plurality of islands and the plurality of bridges are defined based on cutout portions of the substrate, and a vertex of a cutout portion between one of the plurality of islands and a bridge connected to the one of the plurality of islands is an intersection of a straight line and a curved line.