GaAs solar cells promise to break energy efficiency records

According to a report from the American Physicist Organization Network on November 8 (Beijing time), American scientists have used thin gallium arsenide to create a thin-film solar cell with a maximum conversion efficiency of 28.4% through new ideas that are contrary to traditional scientific research. The key to improving the efficiency of this solar cell is not to let it absorb more photons but let it release more photons. Solar cells made with gallium arsenide in the future are expected to exceed the limits of energy efficiency conversion records.

In the past, scientists have emphasized that solar cell efficiency is increased by increasing the amount of solar energy absorbed by photons. The electrons that the solar cell produces after absorbing sunlight must be extracted as electricity, and those that are not extracted quickly enough will decay and release their own energy.

A study led by Eli Yabulnovich, a scientist at the Lawrence Berkeley National Laboratory under the U.S. Department of Energy, showed that if these released energy were emitted as external fluorescence, the output voltage of solar cells would increase. Yabulonovich said: "Our research shows that the more efficient the solar cells are to release photons, the higher their energy conversion efficiency and the higher voltage they provide. External fluorescence is the theoretical maximum of solar cell conversion efficiency - Shockley. The key to the Quantel efficiency limit is about 33.5% for a single pn junction solar cell."

Owen Miller, the participating researcher, explained that in the open circuit environment of solar cells, electrons have nowhere to go and they will be densely packed. Ideally, they emit external fluorescence and precisely balance the incident sunlight. .

Based on this, Alta Equipment Co., co-founded by Albrunovich, used AlGaN's earlier-developed single-crystal thin-film technology, epitaxial lift-off technology, to produce thin-film solar cells with a maximum conversion efficiency of 28.4% using gallium arsenide. battery. This battery not only broke the previous conversion efficiency, its cost is lower than other solar cells. Currently, the most efficient commercial solar cell is made from a single-crystal silicon wafer with a maximum conversion efficiency of 23%. Although gallium arsenide is more expensive than silicon, it is more efficient in collecting photons. In terms of cost performance, gallium arsenide is an ideal material for manufacturing solar cells.

Yabulonovich said: "The high performance of solar cells is related to external fluorescence. Our theory will significantly change the face of future solar cells. We will live in a world where solar cells are very cheap and efficient."