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Fraunhofer Group for Microelectronics

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Record result for black silicon solar cells

 

Comparison of the process used for a standardsilicon solar cell with that used for the black silicon solar cell developed at Fraunhofer HHI. Fig.: Fraunhofer HHI
Comparison of the process used for a standardsilicon solar cell with that used for the black silicon solar cell developed at Fraunhofer HHI. Fig.: Fraunhofer HHI

Obtaining energy from sunlight is about to get more efficient. Researchers at the Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institut HHI, have succeeded in doubling the efficiency of black silicon solar cells. A femtosecond laser pulse method has now made it possible to capture the previously unused infra-red element of sunlight and extract its energy. The highest level of efficiency previously obtained – 2.2%– was the work of a team of scientists at Harvard University.

One of the decisive contributing factors for this process, developed at Fraunhofer HHI in Goslar, is a change made to the silicon base material. The surfaces of silicon wafers are treated with ultra-short laser flashes – femtosecond laser pulses – which makes them turn black. The material is known as “black silicon.” Thanks to this change, the surface of the solar cells can also absorb the infra-red element in sunlight. The infra- red element, which accounts for about  a third of the spectrum, is not captured by conventional solar cells.

There has also been another step forward in improving the efficiency of silicon solar cells: the front texture of the cell and the emitter together form one step in the femtosecond laser pulse process, which reduces the number of steps required to produce a solar cell by approximately one half.

The solar cells thus produced are characterized by current densities in the range of 38 mA/cm² < Jsc < 42 mA/cm². Professor Dr. Wolfgang Schade, director of the project group in Goslar, had this to say: “We can see great potential for development in this technology, and initial consultations with the German photovoltaic industry have been extremely positive.”Kontakt:

Contact:

Dr. Gudrun Quandel
Telefon +49 30 31002-400
gudrun.quandel(at)hhi.fraunhofer.de
Fraunhofer Institute for Telecommunications, Heinrich-Hertz-Institut HHI
Einsteinufer 37
10587 Berlin
Germany
www.hhi.fraunhofer.de