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Efficiency record for solar cell broken

Published on: 14 May, 2008

PhD Bram Hoex (29) and his TU/e colleagues have managed to increase the efficiency of an important type of solar cell from 21.9 to 23.2 percent. This in close cooperation with the German institute Fraunhofer ISE, that built the solar cell.

They presented this world record on Wednesday 14 May, at a large conference on solar energy in San Diego (USA).

Hoex applied an ultra-thin film of aluminum oxide (circa thirty nanometers) on the front of a crystalline silicon solar cell (n-type PERL). This film has an unprecedented high number of built-in negative charges, which ensure that the loss of energy on the surface – which is normally considerable - disappears. Of all the solar light falling onto this type of solar cell, 23.2 percent is now converted into electric energy. That used to be 21.9 percent.

The efficiency improvement brings us one step closer to the breakthrough of solar energy. An improvement of more than one percent may seem modest, yet it can yield millions for solar cell producers. According to Hoex’ calculations the improvement can increase the yield of a production line for solar cells by five millions per year. Expectations are that the application of the ultra-thin film will cost far less.

Hoex gained his PhD on 8 May within the TU/e Department of Applied Physics. In the Plasma & Materials Processing (PMP) research group he was supervised by professor Richard van de Sanden and Erwin Kessels. The specialty of this group is the application of extremely thin layers by means of plasmas. The flimsy aluminum oxide film, developed within the PMP group, may lead to a technological innovation in the field of solar cells. A number of major manufacturers of solar cells have already showed an interest.

Part of Hoex’ work was paid for by the government, as the industrial application of this type of high-efficiency solar cell is coming considerably closer as a result.