A team at the Us National Renewable Energy Laboratory (NREL) has broken the world record for solar cell efficiency. The new device reached nearly 40 percent, with the highest efficiency record of any type of solar cell under real-world conditions.
NREL has developed a new solar cell with an efficiency of nearly 40%, breaking a world record
Under the lighting condition of ordinary sun, the photovoltaic conversion efficiency of the solar cell reaches 39.5%. That's a very important difference. Other experimental solar cells have efficiency as high as 47 percent, but that's in highly concentrated light. Measuring their efficiency in the light of "one sun" gives a better indication of how they perform in the real world.
The new solar cells beat the team's own record of 39.2 percent set in 2020. By comparison, the efficiency of commonly used silicon and emerging peroxide solar cells tops out at about 25 percent, and the tandem solar cells combining the two materials approach 30 percent.
NREL's solar cells are also being tested for performance in space if it is used to power satellites and other spacecraft. Under these conditions, it achieved a respectable 34.2 percent efficiency.
The new solar cell is based on a cell structure called IMM (Inverted Metamorphic multijunction) and consists of three "junctions," components that generate an electric current to light. Each of these knots is made of a different material -- in this case, gallium phosphide at the top, gallium arsenide in the middle, and indium arsenide at the bottom. The three materials specialize in different wavelengths of light, allowing the solar cell as a whole to capture more energy from the entire spectrum.
Another important reason for the new record was the construction of an intermediate layer with a "quantum Wells". Essentially, by sandwiching a conductive layer between two other materials with a wider gap, electrons are confined to two dimensions, which allows the material to capture more light. The middle layer of the solar cell contains up to 300 quantum Wells, taking overall efficiency to new heights.
The breakthrough could be important for solar cell technology, but the team says making this type of cell is still quite expensive. Further work will be needed to reduce these costs and open up new applications.