Nanowires have a number of exciting properties which are not exhibited by 3-D or bulk materials. This is due to the fact that electrons within the nanowires are quantum confined and have energy levels that differ from that of the bulk materials.
Nanowires are nanostructures with a diameter in the order of 10-9 m. They have aspect ratios of more than 1000, and hence they are commonly referred to as one-dimensional nanomaterials.
Silver nanowires have distinct optical, electrical, and thermal properties and are being incorporated into a wide range of products from photovoltaics to biological sensors.
They are incredibly efficient at absorbing and scattering light. Nanowires are characterized by analytical techniques such as scanning electron microscopy, transmission electron microscopy, and atomic force microscopy.
When silver nanowires are in solution, molecules interact with the nanowire surface to form a double layer of charge which prevents aggregation and stabilizes the nanowires.
Manufacturing of Silver Nanowires
Synthesis of silver nanowires can be carried out using a number of chemical methods. Some of them are listed below:
- Polyol method - Silver nanowires are produced using an aqueous solvent in an autoclave at 120° C for 8h.
- Rapid synthesis – Silver nanowires are prepared by mixing polyvinyl pyrrolidone and copper chloride in disposable glass vials. In this method, ethylene glycol is used as a precursor to the reducing agent.
- Template method – This method employs supramolecular nanotubes of amphiphilic cyanine dye in aqueous solution as chemically active templates for the formation of silver nanowires.
- Electroless deposition –Silver nanowires are formed by the electroless deposition of silver into the polycarbonate membranes through metal amplification process.
Applications of Silver Nanowires
Silver nanowires find applications in the following:
- Optical industries - Surface plasmons, medical imaging, solar films, Raman spectroscopy and optical limiters.
- Conductive applications - Touchscreen displays, high-intensity LEDs, and computer boards
- Antibacterial applications – Bandages, sterile equipments, clothing, paints and cosmetics
- Optical applications - Optical spectroscopies such as surface-enhanced Raman scattering and metal-enhanced fluorescence.
Future of Silver Nanowires
In recent years metal nanowires have been extensively studied for their optical properties due to the increasing need for microintegration of electronic systems. This has resulted in the development of several competing technologies to manufacture nanowires.
Out of all metals used as nanostructures, silver exhibits the best electrical conducting properties. Therefore, silver nanowires feature high electrical conductivity with better flexibility and optical transparency, which are critical for manufacturing a number of electronic and optoelectronic devices.
Researchers also believe that these materials can be used as wiring for the miniaturization of quantum devices and ultra large electrical circuits in the near future.
Silver nanowires are a class of silver nanoparticles which have been widely studied for their possible use in several advanced technology applications, thanks to their exciting optical, thermal and electrical properties.
They have gained more attention in recent years due to their small dimensions and potential applications in the field of electronics, optics, acoustics, magnetics and high-performance catalysts.
References and Further Reading