In SİVAS Cumhuriyet University (CU) Nanotechnology Center, studies on the third generation solar cell, the first of which will be produced in Turkey, are being carried out. Cumhuriyet University plans to provide 44 percent energy efficiency from the third generation solar cell, where the world's maximum efficiency is 40 percent.
The Nanotechnology Center, which was established in 2010 at Cumhuriyet University, is working on projects that are the first in Turkey. In Turkey, the metal organic chemical vapor deposition (MOCVD) crystal growth laboratory, which is located only in Cumhuriyet University, continues to produce third generation solar cells by using As/P based augmentation. The project, which started in 2011, is expected to be completed in mid-2014.
USED IN SPACE RESEARCH
CU Nanotechnology Center Director Prof. Dr. Sezai Elagöz stated that there is a TUBITAK project related to third generation solar cells and said:
“Most of the current solar cells are based on silicon, we call them first generation. And because they are quite cheap, they are widely used in the market. Now we have started to see it on the roofs of our houses, on the traffic lights. Of course, these solar cells need to be developed, their efficiency needs to be increased. Currently, it has a working efficiency of around 20 percent. Increasing this efficiency is very important. However, other technologies require much more expensive technologies compared to silicon. Third-generation solar cells are much more expensive than regular silicon-based solar cells. But at the moment, in space research and military applications, since we need to get very high efficiency in a very low area, research on this subject is important and it is increasing rapidly in the world. Our field is a MOCVD system and it is the only system in Turkey that can do As/P based augmentation. Therefore, our studies with this system are the first studies on this subject in Turkey.”
ELECTRIC ENERGY IN 3 LAYERS
Talking about the structure of the third generation solar cell they prepared and comparing it with other batteries, Prof. Dr. Elagöz said, “While incoming sunlight is converted to electrical energy at only one wavelength in normal solar cells, in such a structure, light of different wavelengths is converted into electrical energy in three different regions by ordering them from wide band gap to narrow band gap. So this is a three-story tandem structure. And the efficiency in these structures is almost three times higher than other single-layer tandem solar cells,” he said.
“GROWING THESE BUILDINGS IS AN ART”
Stating that the third generation solar cell is a very logical and easy to understand structure when theoretically looked at, Prof. Dr. Elagoz continued his words as follows:
“It is very difficult to grow this structure. Because we enlarge them by stacking atoms on top of each other. When there are different atoms, they don't want to grow on top of each other. So they create stretches and contractions. That's why growing these structures is an art in the world's terms. Because while you are growing these structures, you are experimenting many times and making calculations. This magnification quality naturally affects the efficiency of solar cells. This type of solar cell currently has a record efficiency of 44 percent in the world. We hope to achieve at least 40 percent efficiency in our country. This work has been going on for about two years. We are about to make the second layer now. After making the third layer, we will get our results. The important thing here is that this structure is fully grown in this system. After we enlarge this structure, we perform its characterizations through our other devices in our center. The final fabrication processes will also be carried out at METU, as our infrastructure is not yet sufficient. However, since we will bring these devices to our laboratory in the future, we will now be able to produce these structures completely here.”