Less energy loss: Chile makes solar cells more effective

Monday, January 18, 2021

Less energy loss
Chili makes solar cells more effective

Chili peppers give each dish the heat it needs. Capsaicin, a secondary plant substance, is responsible for this. Makes the chili spicy and healthy. Researchers are now finding out: Capsaicin can also increase the performance of solar systems.

The substance that warms chili peppers can enhance the process of converting sunlight into electrical energy. Here’s what Chinese and Swedish scientists working with Qinye Bao from the East China Normal University in Shanghai discovered. He processed capsaicin in a perovskite solar cell. This type of solar cell is considered a beacon of hope for a new generation of photovoltaic systems. They are easy to make from inexpensive materials. By adding the chili component, the efficiency of the solar cell could be increased from 19.1 to almost 22 percent.

The reason for this: According to scientists, capsaicin mainly helps to reduce energy losses within the perovskite solar cell. Overall, the efficiency of perovskite solar cells with a single connection (“single junction”) has increased from 3.8 to more than 20 percent since 2009, the researchers write in the journal “Joule.” The highest degree of efficiency achieved so far for the special design examined in the study is 21.93 percent. The capsaicin solar cell being introduced now is almost as efficient at 21.88 percent, but it also has other advantages.

“Given the electrical, chemical, optical and stable properties of capsaicin, we discovered beforehand that it was a very promising candidate,” Bao said in a press release. He and his colleagues only added 0.1 percent capsaicin to the components of the perovskite structure. However, this small amount is sufficient to largely compensate for common weaknesses in the resulting crystal lattice.

Capsaicin conducts electricity better

In these crystal lattice defects, electrons combine with electron defects, also called “holes.” This means that they fail as charge carriers for electrical current. According to scientists, capsaicin can prevent this process and guarantee more free electrons in solar cells. Capsaicin also dampens the connection of electrons with holes in the transition between the positively and negatively charged zone in the crystal lattice. More electricity can be passed on the way.

Capsaicin has another advantage for solar cell stability. At 45 percent relative humidity and room temperature, the capsaicin solar cell, which was not insulated from the outside, retained more than 90 percent of its original efficiency after approximately 33 days of storage. The capsaicin-free solar cell tested as a control only reached 40 percent of the original value after this time. The researchers showed that this effect is partly due to the fact that capsaicin makes solar cells more water repellent.

Bao would like to use natural substances like capsaicin to make perovskite solar cells more environmentally friendly in the future and, if possible, avoid lead, a toxic heavy metal. In any case, the researchers want to use more natural substances in solar cells and avoid problem substances. “In the future, sustainable and environmentally friendly technology for additive biomaterials will be a clear trend for non-toxic and lead-free perovskite materials,” emphasizes the scientist.