New development - ultra-thin transparent film - perfectly conducts electric current. It can be used in electronics, as researchers of nanomaterials at the University of Illinois in Chicago (USA) and Koryo University (South Korea) have found a cheap and easy way to produce such a film. Silver nanowires are used as the conductive material. It can be used in screens of digital electronics, including wearable.
On the left - a large piece of flexible film with silver nanowires. On the right are particles of silver nanowires visible under a microscope.
(CK Yun, University of Koryo)
The film is flexible and stretchable, so it can potentially be used in touch displays, wearable electronics, flexible solar panels, and “electronic skin.” The research results were published in Advanced Functional Materials.
In the new film, nanowires made of fused silver are used. It is produced by spraying nanowire particles at supersonic speeds using a tiny nozzle. As a result, the electrical conductivity of the film approximately corresponds to the electrical conductivity of table silver, notes the leading author of the study, Professor Emeritus of Mechanical Engineering at the University of Illinois at Chicago Alexander Yarin.
He also explained that silver nanowires are fine particles of great length. The length of the nanowire is approximately 20 microns. If four such wires are put together, their total length will be approximately equal to the thickness of a human hair. Can such wires be considered long? It turns out that it is possible, since their diameter is a thousand times smaller than the length, which is significantly smaller than the wavelength of visible light. This property allows to minimize the scattering of light.
The researchers placed the particles of nanowires in water and sprayed them with a Laval nozzle, which with its geometrical characteristics is like a jet engine, but its diameter is only a few millimeters.
The liquid evaporates during the spraying process, explains Professor Yarin. When nanowires applied at supersonic speeds hit the surface, they fuse together because their kinetic energy is converted into heat.
The ideal speed for this process, according to Professor Yarin, is 400 meters per second. If the energy is too high (for example, at a speed of 600 meters per second), the wires may be damaged. If the speed is too low (for example, 200 meters per second), it will simply not be enough to fuse the wires.
The researchers applied the nanowires to both plastic film and three-dimensional objects. It turned out that the shape of the surface on which the nanowires are applied does not matter.
The transparent plastic film can be bent and stretched seven times from its original length, and it will continue to work, the research co-author Professor of Mechanical Engineering of the University of Korea Yoon (Sam Yoon) complements the above.
Earlier this year, Alexander Yarin and Sam Yun and their colleagues created a transparent electrically conductive film by applying copper electroplating on a “mat” of nanofibres. In comparison with the film made with the use of copper, the new development of researchers, involving the deposition of silver nanowires, is characterized by higher scalability and makes it possible to produce it in large volumes.
It is easier and cheaper to produce, since the process of its production is carried out in just one, not two steps.
Based on sciencedaily.com
The article is based on materials .
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