Silver Nanowire Ink Formulation for Transparent Conductive Films
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Solution Overview
Problem
Current methods for producing transparent conductive films using metal oxide thin films are limited by low flexibility, high energy consumption, and visibility issues due to thickness requirements, while silver nanowires offer a promising alternative but face challenges in achieving high conductivity, transparency, and adhesiveness.
Innovation Solution
A silver nanowires ink is developed by dispersing silver nanowires in a solvent with a water-soluble acrylic-urethane copolymer resin and a viscosity modifier, achieving a specific aspect ratio and viscosity range to form a transparent conductive coated film with improved conductivity, light transmittance, and adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal oxide thin films are used for transparent conductive films, then high transparency and conductivity can be achieved, but the films have low resistance to bending and require vacuum deposition equipment
Solution Approach 1:
The patent replaces vacuum deposition methods with a solution-based coating method. Silver nanowires are dispersed in a solvent to form an ink, which is then coated onto the substrate using simple coating equipment, eliminating the need for complex vacuum deposition systems while achieving comparable or superior electrical and optical properties.
Solution Approach 2:
The patent changes the material form from metal oxide thin films to silver nanowire dispersions. By controlling the aspect ratio of silver nanowires (length/diameter ≥ 100) and their concentration in the ink, the patent achieves high conductivity and transparency without requiring vacuum processing conditions.
2Reliability
If ITO film thickness is increased to enhance conductivity, then conductivity improves, but transparency decreases
Solution Approach 1:
The patent uses silver nanowires with high aspect ratio (length/diameter ≥ 100) to achieve high conductivity at very low solid content (0.1-5 wt%). The nanowire network forms efficient conduction paths without requiring high material concentration, thereby maintaining excellent transparency while achieving low sheet resistance.
Solution Approach 2:
The patent creates a composite structure where silver nanowires are dispersed in a transparent solvent with controlled viscosity. The nanowire network forms a conductive framework that allows electrical conduction without blocking light, achieving both high conductivity and transparency simultaneously.
3Adaptability or versatility
If silver nanowires are used to form conductive network, then flexibility and transparency are improved, but adhesiveness deteriorates
Solution Approach 1:
The patent uses a specifically formulated solvent as an intermediary medium. The solvent contains a binder component that adsorbs onto the silver nanowire surface and also adheres to the substrate, creating strong interfacial bonding. This binder acts as a mediator that transfers stress between the nanowire network and substrate, preventing delamination while maintaining flexibility.
Solution Approach 2:
The patent creates a composite ink system consisting of silver nanowires, binder, and solvent. The binder component forms a matrix that holds the nanowires together and bonds them to the substrate, creating a unified flexible conductive film with excellent adhesiveness.
4Ease of manufacture
If vacuum vapor deposition or sputtering methods are used, then transparent conductive films can be produced, but large and complicated equipment is required and large amount of energy is consumed
Solution Approach 1:
The patent replaces energy-intensive vacuum deposition and sputtering processes with a low-energy solution coating method. The silver nanowire ink is applied to the substrate at or near ambient conditions, requiring minimal energy input compared to vacuum systems that must maintain high vacuum and heat the substrate for film deposition.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method results in a transparent conductive coated film with excellent conductivity, optical characteristics, and adhesiveness, suitable for industrial applications, overcoming the limitations of traditional metal oxide films.
Implementation Method 1
dispersing silver nanowires in a solvent with a water-soluble acrylic-urethane copolymer resin
Implementation Method 2
achieving a specific aspect ratio and viscosity range
Data Source
Figure 1
AI summary
Problem To provide a technique having high industrial practicality for providing a transparent conductive coated film that is excellent in conductivity, light transmissibility, haze characteristics, and adhesiveness. Solution A method for producing a silver nanowires ink, containing adding a viscosity modifier and a water-soluble acrylic-urethane copolymer resin, to an aqueous solvent or a mixed solvent of water and an alcohol having silver nanowires dispersed therein. The content of the water-soluble acrylic-urethane copolymer resin with respect to the total amount of the silver nanowires ink may be from 0.05 to 2.0% by mass. The content of silver with respect to the total amount of the silver nanowires ink is preferably from 0.05 to 1.0% by mass. The content of the viscosity modifier with respect to the total amount of the silver nanowires ink is preferably from 0.01 to 1.0% by mass. The viscosity of the silver nanowires ink is preferably controlled to a range of from 1 to 100 mPa·s.