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According to a report from the American Physicist Organization website on November 8 (Beijing time), American scientists used gallium arsenide to create a thin-film solar cell with a maximum conversion efficiency of 28.4% through a new idea that is contrary to traditional scientific research. The key to improving the efficiency of this solar cell is not to let it absorb more photons but to let it release more photons. In the future, solar cells made of gallium arsenide are expected to break the limit of energy efficiency conversion records. In the past, scientists have emphasized improving the efficiency of solar cells by increasing the number of photons absorbed from the sun. The electrons produced when a solar cell absorbs sunlight must be extracted as electricity, and those that are not extracted quickly enough decay and release their own energy. Lawrence Berkeley of the U.S. Department of Energy * * Research led by laboratory scientist Eli Yabrunovich shows that if this released energy is emitted as external fluorescence, the output voltage of the solar cell increases. Jabrunovitch says: “Our research shows that the more efficiently a solar cell releases photons, the higher its energy conversion efficiency and voltage it provides. External fluorescence is the key to achieving the theoretical maximum of solar cell conversion efficiency - the Shockley-Quesser efficiency limit. For a single pn junction solar cell, this maximum value is approximately 33.5%. ” Participating researcher Irwin Miller explained that in the open-circuit environment of a solar cell, electrons have nowhere to go and are packed together. Ideally, they emit external fluorescence that precisely balances the incoming sunlight. Based on this, Alta Equipment Company, co-founded by Yabrunovich, used epitaxial layer peeling technology, a single crystal thin film technology developed early by Yabrunovich, to use gallium arsenide to create a thin-film solar cell with a maximum conversion efficiency of 28.4%. This kind of battery not only breaks the previous conversion efficiency, but its cost is also lower than other solar cells. Currently, the most efficient commercial solar cells are made from monocrystalline silicon wafers, with a maximum conversion efficiency of 23%. Although gallium arsenide is more expensive than silicon, it collects photons more efficiently. In terms of cost performance, gallium arsenide is an ideal material for manufacturing solar cells. Jabrunovitch says: “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. ”