Polyurethane Touch Panel with Nanowire Electrodes for Flexible OLEDs
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Solution Overview
Problem
Existing touch panels for organic light emitting diode (OLED) displays face challenges in maintaining flexibility and preventing damage from bending and stretching, while ensuring high conductivity and transmittance, particularly due to the susceptibility of thin films to mechanical stress.
Innovation Solution
A touch panel design featuring a polyurethane substrate with a first electrode layer of metal nanowires, a polyurethane overcoat layer with a reduced in-plane phase difference, and a second electrode layer made of transparent conductive materials, which includes a primer layer to enhance adhesion and flexibility, and is capable of filling gaps between metal nanowires, thereby improving durability and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If thin films are used in touch panels to reduce thickness and weight, then flexibility and portability are improved, but the thin films become susceptible to mechanical stress from bending and stretching
Solution Approach 1:
The patent employs flexible polyurethane substrates and overcoat layers instead of rigid glass substrates. The polyurethane material inherently provides flexibility and elasticity, allowing the touch panel to withstand bending and stretching without breaking, thus resolving the contradiction between thinness and mechanical durability
Solution Approach 2:
The patent uses composite structures including polyurethane substrate, metal nanowire electrode layers, and polyurethane overcoat layers. This multi-layer composite design combines the flexibility of polyurethane with the conductivity of metal nanowires, achieving both lightweight construction and mechanical resilience
2Reliability
If metal nanowires are used as electrode material to improve conductivity and transmittance, then electrical performance is improved, but the nanowire network becomes vulnerable to disconnection under mechanical stress
Solution Approach 1:
The polyurethane overcoat layer acts as a flexible protective film that encapsulates the metal nanowire network. This flexible coating prevents the nanowires from breaking or disconnecting during bending and stretching while maintaining their electrical connectivity and optical transmittance
Solution Approach 2:
The polyurethane overcoat layer is applied in advance to protect the metal nanowire electrode from mechanical damage. This protective layer cushions the nanowires against stress from bending and stretching before damage can occur, ensuring continuous electrical performance
3Ease of manufacture
If conventional touch panel structures are used, then manufacturing simplicity is maintained, but flexibility and durability under bending stress are insufficient
Solution Approach 1:
The patent replaces conventional rigid glass substrates with flexible polyurethane substrates and uses polyurethane overcoat layers instead of rigid protective coatings. This substitution maintains the layered manufacturing approach while fundamentally improving flexibility and bending durability
Solution Approach 2:
The patent changes the material parameters from rigid to flexible by using polyurethane with specific elastic properties. The polyurethane substrate and overcoat layers are designed with appropriate thickness and mechanical properties to achieve the desired flexibility while maintaining structural integrity during manufacturing and use
Data Source
AI summary
A touch panel, including a polyurethane substrate; a touch electrode including a first electrode layer on the polyurethane substrate, the first electrode including nanowires; and a polyurethane overcoat layer on the touch electrode, the polyurethane overcoat layer having an in-plane phase difference smaller than that of the polyurethane substrate.