Segmented OLED Anode with Conductive Bridge for Flexible Displays
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Solution Overview
Problem
Flexible OLED display panels face cracking issues due to uneven stress on rigid anode layers during bending, which reduces display pixel brightness and can lead to device failure.
Innovation Solution
The use of a flexible substrate with a channel-defined first and second anode connected by a flexible electrically-conductive assembly of silver or metallic carbon nanowires, along with a planarization insulating layer and organic light emitting layers, enhances the anode's flexibility and reduces stress-induced cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transparent electrically-conductive oxide such as ITO is used for the anode, then electrical conductivity and transparency are improved, but flexibility deteriorates and crack resistance worsens
Solution Approach 1:
The anode is segmented into multiple discrete anode islands instead of a continuous layer. This segmentation reduces the overall length of the anode in the bending direction, thereby reducing stress accumulation and improving flexibility while maintaining electrical conductivity through each individual anode island.
Solution Approach 2:
A flexible electrically-conductive assembly is introduced as an intermediary component to bridge the gap between separated anode islands. This assembly maintains electrical connectivity while accommodating bending stresses, effectively decoupling the electrical conductivity requirement from the mechanical flexibility constraint.
2Reliability
If the anode is made continuous to ensure electrical connectivity, then electrical conductivity is improved, but stress concentration increases leading to cracks
Solution Approach 1:
The continuous anode layer is divided into multiple discrete anode islands spaced apart from each other. This segmentation eliminates stress concentration at continuous interfaces while maintaining electrical connectivity through the flexible electrically-conductive assembly that bridges the islands.
Solution Approach 2:
Different regions of the device are assigned different functions: anode islands provide localized electrical contact points, the flexible electrically-conductive assembly provides localized electrical connectivity between islands, and the spaces between islands accommodate bending stresses. This local differentiation resolves the contradiction between connectivity and stress resistance.
Data Source
AI summary
The invention discloses an OLED device including: a flexible substrate; a first anode and a second anode on the flexible substrate and being spaced from each other to form a channel therebetween; a flexible electrically-conductive assembly in the channel and connecting the first anode with the second anode; a first organic light emitting layer on the first anode and a second organic light emitting layer on the second anode; and a cathode on the first and the second organic light emitting layers. The invention can improve the flexibility of the anode of the OLED device, reduce an actual continuous length of the anode on a bending direction, reduce the probability of crack generation in the process of the OLED device being bent by external force, and therefore can increase bendable and wearable abilities of a flexible OLED display device formed by such OLED device.