New technique for making cheaper solar cells

Ars Technica : A new technique for doping semiconductors may pave the way for making solar cells from materials that are cheaper and more abundant than those currently used. Doping boosts the efficiency of solar cells by making it easier to extract light-induced charge. Silicon, the most widely used semiconductor in solar cells, is cheap, but doping it is not. Alternative semiconductors, such as metal phosphides and metal sulfides, are cheaper to dope, but the doping process either destroys the material directly or causes the cell to degrade over time. Researchers at Lawrence Berkeley National Laboratory and the University of California, Berkeley, have figured out a way to achieve the efficiency boost that chemical doping brings, but without incorporating actual dopants. They shape one of the electrodes attached to the semiconductor and maintain a very low electric field across its surface, which has the same effect as doping. Their demonstration device was made from copper oxide and silicon. Lead author Will Regan says that the next step is to determine what semiconductor is the best option and then to convert the process to the industrial scale.