Solar Cells, Reborn through Nano Design?
-Special Interview with Professor Chang-Hee Cho and Senior Researcher Seong Ho Baek
DGIST, there are many opportunities to exchange research content. Once a year,
Convergence Research Festivals are held, and on the second and fourth Tuesdays
of each month, small-scale seminars are also held. At the festival, Professor Chang-Hee
Cho suggested an idea that I had not thought about, and that became the
starting point of my convergence research."
Researcher, Seong Ho Baek from the DGIST Smart Textile Convergence Research
Group recalled three years ago when he first discussed his research topic with
Professor Chang-Hee Cho from the Department of Emerging Materials Science.
Professor Cho started talking about the research to Baek who had been
researching solar cells that convert solar light energy into electric energy by
saying, "Why don"t we try to do the basic research together to make a semiconductor,
which is a basic element of solar cells, absorb solar light well?"
Nanoscience to Semiconductors
photoelectric conversion efficiency of solar cells is good" means they absorb
more light and convert it to electric energy as efficiently as possible. The
ability to absorb light at this time is called "light absorption efficiency".
It depends on the light absorbing ability of the semiconductor, which is the
basic element of the solar cells. Professor Cho said that, "I thought the
nanotechnology field that I was researching was the key to overcoming the
limitations of solar cells that senior researcher Baek was researching at that
time." The idea was to increase the light absorption efficiency by forming
a nanomaterial with a specific pattern on the existing semiconductor surface.
He then explained, "Since then, we have been meeting more than once a week
and developing our research."
years after the research, the two succeeded in increasing the light absorption
efficiency by designing nanostructures in semiconductors for the first time and
published the results as a cover paper in the April 2016 issue of "Advanced
Materials". Professor Cho said, “Semiconductors that absorb light well at
specific wavelengths can absorb light at high efficiency at wide wavelengths in
the visible light range.”
Cho and senior researcher Baek have formed nanostructures with wave-like
periodicity on the surface of a cylindrical structure on a semiconductor
surface. As a result, a resonance phenomenon was caused by the reaction with
the light within a wide wavelength and the absorption rate increased by the
light of the visible light range staying longer on the semiconductor. In the
course of the research, the two thought that nanodesign semiconductors that
absorb more light could be applied to high performance optical sensor
technology in addition to solar cells. Professor Cho then added, "Light
sensors can convert light into electrical signals, so by adjusting the design
of the nanostructure, the sensitivity of the sensor can be improved."
its fourth year, their encounter is not over yet. Professor Cho said, "In
recent years, senior researcher Baek has helped other research teams by
suggesting applications of our nano semiconductor design technology to photo-electrochemical
is a growing interest in research on clean renewable energy sources. Among
them, hydrogen is considered a clean energy source. When separating water into
hydrogen and oxygen, light acts as a catalyst. Things that play such roles are
called the photoelectric chemical devices. In fact, the light absorbed by this
device helps catalysis. Professor Cho and senior researcher Baek have designed
a photoelectric chemical device in the form of a disk, which has been used in
thin film form, and has increased light absorption by causing resonance with
light at a specific wavelength. Professor Cho said, "A paper on photo-electrochemical
devices was published in the journal "Energy and Environmental Science"
in June 2016. With the research with senior researcher Baek, I have written
three papers and applied for two patents so far."
the two are working on their next study on the topic of solar cells. When light
absorbed by semiconductors is converted into electrical signals, metal is
needed. It is their goal to increase the conversion efficiency of electrical
signals by applying nanodesign to these metals.
X Chemistry Exploded
convergence research between the two, which has continued for three years, has
become a representative model for win-win cooperation research between research
institutes and colleges at DGIST. Senior researcher Seong Ho Baek said, “Since
I started my research voluntarily rather than at the request of an institution
or society, I was able to succeed through continuous communication.” Professor
Cho then added, “There is often a chemical reaction that occurs between people.
With people whom you lack chemistry, it is difficult to get along no matter how
hard you try. Fortunately, the more we conduct research, the better our
Original version of this
article appears on the Donga Science, By: Lee Gyu Chul
Translation: International Affairs Team