Black Silicon Solar Cell Efficiency Record Broken

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Researchers at Fraunhofer ISE of Germany and Aalto University of Finland have developed a black silicon solar cell that achieved 18.7% efficiency.

This is the highest efficiency reported for a black silicon solar cell technology.

Black Silicon. Image Credit: SEM_of_RIE_Black_Silicon.tif: Blind cyclist
Black Silicon. Image Credit: SEM_of_RIE_Black_Silicon.tifBlind cyclist

18.7% efficiency means a power-to-size ratio of 187 watts per square meter of these cells. 7,000 watts (7 kW) of these cells would require only 37.4 square metres (402 square feet) of roof space.

The previous efficiency record of 18.2% was held by the US Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL).

The Fraunhofer ISE and Aalto University researchers pulled it off the new efficiency record by applying a boron diffusion to create a pn-junction, “maintaining the excellent optical properties of the black silicon structure,” as the press release writes. The previous NREL record was achieved using thermal oxidation as a passivating layer.

“The quantum efficiency measurements reveal that the nanostructured front surface is of a high electrical quality comparable to a pyramidal textured surface, says Assistant Professor Hele Savin of Aalto University.”

The researchers have already identified ways to further improve the efficiency of the black silicon solar cells, and they believe that efficiencies much higher than 20% can certainly be achieved.

There seems to be a good back and forth of black silicon solar cell news between Fraunhofer and NREL (often in combination with Natcore Tech), a sort of see-saw  of black silicon improvements, sometimes announced within days of each other.

A paper about the recent improvement, “Passivation of Black Silicon Boron Emitters with ALD Al2O3,” was written by Päivikki Repo, Ville Vähänissi, Guillaume von Gastrow, Jan Benick, Jonas Schön, Bernd Steinhauser, Martin C. Schubert, and Hele Savin. It was presented at SiliconPV, the 3rd International Conference on Crystalline Silicon Photovoltaics, March 25–27 2013 in Hamelin, Germany.

If you’d like more information, below is contact information for two of the scientists.

Scientist Contact Information

Research Scientist Päivikki Repo
Aalto University
Tel. +358 50 436 1156

Assistant Professor Hele Savin
Aalto University
Tel. +358 50 541 0156

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Nicholas Brown

Has a keen interest in physics-intensive topics such as electricity generation, refrigeration and air conditioning technology, energy storage, and geography. His website is:

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