A Transport Technology for Nanowires Thermally Treated at 700 Celsius Degrees
Jun-Bo Yoon and his research team of the Department of Electrical Engineering
at KAIST developed a technology for transporting thermally treated nanowires to
a flexible substrate and created a high performance device for collecting flexible
energy by using the new technology.
Min-Ho Seo, a Ph.D. candidate, participated in this study as the first author.
The results were published online on January 30th in ACS Nano, an international journal in
the field of nanoscience and engineering. (“Versatile Transfer of an Ultralong
and Seamless Nanowire Array Crystallized at High Temperature for Use in High-performance
Flexible Devices,” DOI: 10.1021/acsnano.6b06842)
are one of the most representative nanomaterials. They have wire structures
with dimensions in nanometers. The nanowires are widely used in the scientific
and engineering fields due to their prominent physical and chemical properties that
depend on a one-dimensional structure, and their high applicability.
have much higher performance if their structure has unique features such as an excellent
arrangement and a longer-than-average length. Many researchers are thus
actively participating in the research for making nanowires without much
difficulty, analyzing them, and developing them for high performance
have recently favored a research topic on making nanowires chemically and
physically on a flexible substrate and applies the nanowires to a flexible electric
device such as a high performance wearable sensor.
existing technology, however, mixed nanowires from a chemical synthesis with a
solution and spread the mixture on a flexible substrate. The resultant
distribution was random, and it was difficult to produce a high performance
device based on the structural advantages of nanowires. In addition, the technology
used a cutting edge nano-process and flexible materials, but this was not economically
beneficial. The production of stable materials at a temperature of 700 Celsius degrees or higher is unattainable,
a great challenge for the application.
solve this problem, the research team developed a new nano-transfer technology
that combines a silicon nano-grating board with a large surface area and a nano-sacrificial
layer process. A nano-sacrificial layer exists between nanowires and a nano-grating
board, which acts as the mold for the nano-transfer. The new technology allows the
device undergo thermal treatment. After this, the layer disappears when the
nanowires are transported to a flexible substrate.
technology also permits the stable production of nanowires with secured
properties at an extremely high temperature. In this case, the nanowires are
neatly organized on a flexible substrate. The research team used the technology
to manufacture barium carbonate nanowires on top of the flexible substrate. The
wires secured their properties at a temperature of 700℃ or
above. The team employed the collection of wearable
energy to obtain much higher electrical energy than that of an energy
collecting device designed based on regular barium titanate nanowires.
researchers said that their technology is built upon a semiconductor process, known
as Physical Vapor Deposition that allows various materials such as ceramics and
semiconductors to be used for flexible substrates of nanowires. They expected
that high performance flexible electric devices such as
flexible transistors and thermoelectric elements can be produced with this
Seo said, “In this study, we transported nanowire materials with developed
properties on a flexible substrate and showed an increase in device
performance. Our technology will be fundamental to the production of various
nanowires on a flexible substrate as well as the feasibility of making high
performance wearable electric devices.”
research was supported by the Leap Research Support Program of the National
Research Foundation of Korea.
1. Transcription process of new, developed nanowires (a) and a fundamental
mimetic diagram of a nano-sacrificial layer (b)
Fig. 2. Transcription results from using gold
(AU) nanowires. The categories of the results were (a) optical images, (b)
physical signals, (c) cross-sectional images from a scanning electron
microscope (SEM), and (d-f) an electric verification of whether the perfectly
arranged nanowires were made on a large surface.
Fig. 3. Transcription from using barium titanate
(BaTiO3) nanowires. The results were (a) optical images, (b-e) top images taken
from an SEM in various locations, and (f, g) property analysis.
Fig. 4. Mimetic diagram of the energy collecting
device from using a BaTiO3 nanowire substrate and an optical image of the
experiment for the miniature energy collecting device attached to an index