Fraunhofer Researchers Develop the World’s Most Efficient Solar Cell

Researchers at the Germany based Fraunhofer Institute for Solar Energy Systems ISE, using a new antireflection coating, claimed on May 30 to have successfully developed the most efficient solar cell of the world. Presenting the results at the 2nd International tandem PV Workshop in Germany, the researchers claimed to have increased the efficiency of the best four-junction solar cell to date from 46.1 to 47.6 percent at a concentration of 665 suns. This is a global milestone, as there is currently no solar cell with a higher efficiency worldwide. The Institute performs applied scientific and engineering research and development for all areas of solar energy.

Dr. Frank Dimroth, department head of III-V Photovoltaics and Concentrator Technology at Fraunhofer ISE, said, “We are thrilled with this result, which was achieved only one year after the opening of our new Center for High Efficiency Solar Cells. In our research, we aim to make concentrating photovoltaics even more efficient and competitive, as we believe that this is the most sustainable form of renewable electricity generation.”

The layer structure of this solar cell was developed back in 2016 alongside French semiconductor manufacturer Soitec, with the upper tandem solar cell made of gallium indium phosphide (GaInP) and aluminium gallium arsenide (AlGaAs), attached to a lower tandem solar cell made of gallium indium arsenide phosphide (GaInAsP) and gallium indium arsenide (GaInAs). Conventional solar cells made of silicon can only absorb sunlight up to a wavelength of 1200 nanometres but Fraunhofer ISE’s record-breaking solar cell managed to expand the broad range up to 1780 nanometres.

The feature comes only two years after Fraunhofer started the “50 Percent” project, which aims to develop a solar cell with a 50% efficiency, and only one year after it opened its new Center for High Efficiency Solar Cells, said Frank Dimroth. Multi-junction solar cells made of III-V compound semiconductors reach their highest potential when the incoming sunlight is concentrated by lenses onto miniature solar cell devices of just a few square millimeters in size.

Multi-junction solar cells made of III-V compound semiconductors have always been among the most efficient solar cells in the world. “Possible applications of such highly efficient tandem solar cells include concentrator photovoltaic systems, which contribute to efficient power generation in sun-rich countries,” says Prof. Dr. Stefan Glunz, division director of Photovoltaics Research at Fraunhofer ISE. “With tandem photovoltaics, it is possible to leave the limitations of single-junction solar cells behind and ultimately achieve a reduction in solar power costs.”