▲ ETRI researchers explaining the color thin-film solar cell technology From left, Senior Researcher Yong-Deok Jung and Dae-Hyung Cho, Senior Researcher. (Photo courtesyf=ETRI)                          © World Lighting News.

 

 

Written by : Min-Woo Lee. Journalist.

 

While research on solar cells to secure new and renewable energy sources is intensifying, domestic researchers have succeeded in implementing color solar cells that will add

beauty to the urban environment. This is expected to enable various applications of'solar

cells'.

Electronics and Telecommunications Research Institute (ETRI) is an eco-friendly color CIGS (copper (Cu), indium (In), gallium (Ga), selenium (Se)) that can implement various colors

without additional process or cost to the existing dark-colored solar cells. ), a compound consisting of Cu(In,Ga)Se2] thin film solar cell.

 

In addition, optical pumping (operation method in which light is irradiated to atoms or

ions to excite from low energy to high state) terahertz spectroscopy (a very high

frequency terahertz is irradiated to a substance and It is said that the world's first

explanation of the efficiency improvement mechanism was possible using the method of measuring properties.

The research results were published in the world-class international journals in the field of energy, “Nano Energy” and “Progress in Photovoltaics,” respectively, proving the excellence of technology.

 

◆ 'CIGS thin film solar cell' manufacturing method

CIGS thin-film solar cells are next-generation solar cells used to convert sunlight into

electrical energy, and are manufactured by stacking CIGS in a thin film on a glass

substrate.

Among the non-silicon-based solar cells, it has the advantage of having the highest light

absorption rate and the highest energy conversion efficiency and good stability. In

addition, raw material consumption is lower than that of silicon-based solar cells, and

process and material costs are also lower.

However, there is a disadvantage that commercialization is difficult because a material

containing cadmium, which is a harmful heavy metal, is used as a buffer layer (a role to

mitigate the difference in lattice constant and band gap between the transparent

conductive layer and the absorbing layer).

At this time, the ETRI researchers succeeded in achieving a similar conversion efficiency

(the ratio of conversion from sunlight to electric energy) of about 18% by using a material containing zinc (Zn) that is harmless to the human body as a substitute for cadmium

sulfide (CdS). Is expected to be partially resolved.

In addition, it is evaluated that it has taken one step closer to commercialization as it can realize more than 7 colors such as purple, green, and blue in solar cells without additional processes or costs.

◆ Succeeded in color realization by focusing on the 'light interference phenomenon'

The researchers explained that they succeeded in implementing various colors by

adjusting the thickness of the thin film constituent layer by focusing on the interference of light that appears as a rainbow of oil bands floating on the water.

The thickness of the thin-film solar cell implemented by the researchers is only 3㎛, and it is possible to coat not only glass substrates but also flexible substrates. Since it can be

manufactured in a form that can be bent or folded, it is expected to be used as a

next-generation eco-friendly energy source, such as attaching it to a building window.

In addition, the researchers succeeded in identifying a mechanism for improving solar cell efficiency with a new analysis method. Until now, academia has not been able to

accurately determine the cause of the phenomenon that the conversion efficiency

increases as the solar cell is exposed to sunlight for a long time.

 

At this time, the researchers measured the motion of the electric charge in the solar cell

that was excited after light pumping using light pumping terahertz spectroscopy (atoms or molecules accept energy from the outside and move to a higher energy state).

 

The direct principle of improving efficiency while deriving (time constant) was explained

for the first time in the world. As ETRI developed a new analysis method, it suggested the possibility of further enhancing the technology for manufacturing eco-friendly

high-efficiency solar cells.

 

◆ It is expected to contribute to urban solar power generation

"This technology will be able to contribute to urban solar power generation by producing high-value-added solar cell products and creating next-generation application fields," said Senior Researcher Jeong Yong-deok, the research director.

The researchers plan to develop and support commercialization of business models to

apply eco-friendly color CIGS thin film solar cell manufacturing technology to solar

modules, urban building construction materials, and mobile or portable devices.

In addition, by applying eco-friendly color realization technology to flexible substrates, it is planning to develop a high-efficiency solar cell that is light and has excellent aesthetics.
Seong-won Kang, director of the ICT Creative Research Center at ETRI, said, “In the

modern society where the supply and demand of electricity is unbalanced, securing the

next generation of renewable energy sources has become very important. We will lead the development of thin-film solar cell technology to prepare for the future society and

contribute to securing an eco-friendly future energy source.”

This study was carried out as part of the task of "Development of Multicolor Flexible Thin Film Solar Cell Technology with Non-Toxic Buffer Layer" in the Task of 『Development of

High-Performance Flexible Inorganic Thin Film Solar Cell Source Technology for Urban

Distributed Power Supply』 by the Ministry of Science and Technology Information and

Communication KAIST, Yonsei University, and POSTECH contributed to the research based on ETRI's original semiconductor and display technology.

 

The first author of the thesis is Senior Researcher Dae-Hyung Cho and Senior Researcher Woo-jung Lee, and the corresponding author is Senior Researcher Yong-Duk Chung.

 

 

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