Black silicon treatment achieves record PV energy performance

June 05, 2015 // By Paul Buckley
Researchers at the Department of Electronic Engineering of the Universitat Politècnica de Catalunya (UPC) have achieved a record efficiency of 22% by creating silicon solar cells that incorporate a surface treatment called black silicon on the front of the cell.

The technique treats the surface with a dry chemical that creates small conical tips at the nanometric scale.

Incorporating black silicon reduces the loss of energy caused by the reflectance of solar cells to almost zero thereby increasing the yield, by almost 4% compared with traditional solar cells.

The extra improvement in efficiency would allow a refrigerator to run for a day in a photovoltaic system composed of a 5 m2 panel.

To ensure that solar cells reflect as little light as possible and prevent energy loss, they are textured using an alkaline bath that forms a rough surface on which pyramids are randomly distributed. The technique makes the cells thicker because it consumes an amount of silicon in the process. Black silicon, however, allows thin silicon cells to be used, lowering production costs and saving silicon.