Professor Lee Jin-ki of the Mechanical Engineering has developed glass for solar cells inspired by plants.
- 공과대학
- Hit4470
- 2021-01-24
Professor Lee Jin-ki of the Mechanical Engineering has developed glass for solar cells inspired by plants.
Solar cells can make electricity only when the sun is up. As time is limited, it is important to increase efficiency of power generation. Its power generation efficiency is not only affected by solar cell materials but also environmental factors such as fine dust that blocks sunlight. Scientists have found answers in nature to increase solar cell efficiency. It mimics the unique moth eye structure that absorbs light well and plants that bounce off pollutants.
◇ Increase light absorption by mimicking moth eyes
Koh Doo-hyun, a professor of applied chemistry at Kyung Hee University, and Kim Sun-kyung, a co-researcher of applied physics, said, "We have developed a film that can increase the efficiency of solar cells by 46 percent by mimicking the eye structure of moths." The research results were published in the international journal 'Advanced Energy Materials' on the 26th of last month.
Moths operating at night have a unique eye structure that absorbs light well. This is because you have to see well in the dark, and when light reflects at night, it is easy to be eaten by natural enemies. On the surface of the moth's eye, small bumps, which are about 100£ (nanometers, 1£ is one billionth of a meter), are gathered. If it is a plane, it reflects light outward, but even if it is a bump structure, it eventually heads inward. It absorbs more light.
Researchers have developed a film that will increase efficiency of translucent solar cells by mimicking the moth eye structure. Translucent solar cells are a thin form of electrodes from conventional solar cells. Although it has the advantage of being permeable and having light flowing in both directions, the loss of light was also significant.
The researchers created a structure in which small triangular horns of hundreds of square feet were densely built on a hemispherical surface measuring 10 £ (micrometer, 1 £ is 1 millionth of a meter). This structure reduces the reflection of light. It also sends light that goes inside the solar cell and reflects back inside the cell. It allows more light to stay in the solar cell. In fact, when the film was attached, the efficiency of translucent solar cells increased by 13.49% for outdoor light and 46.19% for indoor light.
The researchers said both the absorption rate and efficiency of light, regardless of the type of light, such as sunlight or indoor lighting, and regardless of the direction of light. It is expected to be applied to solar cells that can be operated all day with solar power during the day and indoor lighting at night. Professor Ko Doo-hyun said, "It can be used not only for solar cells but also for improving efficiency of various materials such as displays and sensors."
◇ Glass that treats wounds with plant structure
Researchers at Finland's Oulu University announced in June that they created materials to increase the efficiency of solar cells by mimicking butterfly wings in the international journal "Sun Energy." Butterflies and moth wings also have special nanostructures. The black part of the butterfly's wings looks dark because these nanostructures absorb all the light.
Although it varies slightly from species to species, most butterflies and moth wings are made up of bumps-shaped nanostructures. The researchers said that the reflection rate of light decreased from 35 percent to 5 percent after attaching a structure that mimics butterfly wings to solar panels. The maximum current available from solar cells has also increased by 66 percent.
Plant-inspired glass for solar cells has also been developed. "We made glass for solar cells by coating paraffin on the surface of nanofluoride and reducing light reflection," said Lim Hyun-hyun, a senior researcher at the Korea Institute of Machinery and Materials. The study, conducted jointly with Professor Lee Jin-ki of Sungkyunkwan University, was published in the international journal "ACS Nano" in July.
The researchers came up with the idea from the slippery surface of the wormhole. The surface of the wormwood has many holes and is oiled. If a bug goes in, it's slippery and can't get out. Implementing these characteristics can cause dust or pollutants to slip without being buried on the surface.
However, oil, a liquid lubricant, disappears when washed with rainwater. Coating glass can also disappear from the process of wiping off any contaminants on the surface.
Instead of oil, the researchers used paraffin, a solid lubricant like wax in plants, to coat the surface of glass. Paraffin does not react with water. The researchers used this characteristic to coat paraffin on nanostructures that mimic the eyes of moths.
Paraffin has a low melting point of 46 to 68 degrees Celsius, allowing it to melt and harden in the sun. Even if paraffin is damaged during the glass cleaning process, if exposed to the sun for about five minutes, paraffin melts and hardens again and recovers on its own.
Paraffin also has low thermal conductivity. For this reason, ice does not form easily on glass even in cold winter, and even if ice occurs, it can be easily removed. Lim Hyun-hyun, head of the Mechanical Research Institute, said, "By utilizing this technology, glass can maintain its own recovery function longer than before."