Humble compounds exhibit solar value
Eight abundant compound semiconductors can meet the world s energy needs at a lower extraction cost than crystalline silicon when used in single-junction solar cells.
So say Cyrus Wadia, Paul Alivistos and Daniel Kammen of University of California, Berkeley, who have performed an analysis of 23 possible photovoltaic cell materials.
Their assessments of the overall amount of electricity each material could produce and their minimum raw cost found that FeS2 - also known as iron pyrite, or fool s gold - led the field in each case. The minimum theoretical cost of producing the compound was just $0.019/MW.
“Basic science research directed at new material candidates could develop into a viable low cost and highly scalable means of electricity generation,” Wadia told compoundsemiconductor.net.
Wadia will discuss his findings, published in Environmental Science and Technology, at the Materials Research Society meeting in San Francisco on April 14.
According to the Berkeley team each of twelve different semiconductors can meet the world s entire energy needs by themselves with less than one year s worth of their total annual production. This included GaAs, which came out with the third highest minimum raw cost at $250,000/MW in the flat-panel solar model, and both amorphous and crystalline silicon.
FeS2, Cu2ZnSnS4 (CZTS), CuO, Cu2S, PbS, NiS, CdS and Zn3P2 were the compounds with such an abundance and with cheaper raw costs than crystalline silicon.
However, other than FeS2, these were all significantly more expensive than the $1.8/MW theoretical minimum raw material cost of amorphous silicon.
By contrast, total known reserves for raw materials of the currently popular CdTe and copper-indium-gallium-diselenide (CIGS) are only just enough to meet the current 17,000 TWh global electricity demand.
Although all of the semiconductor materials chosen by the Berkeley researchers have been shown to work as photovoltaic cells, the most novel of them are still at an embryonic stage of development.
“These materials may not be market ready for over ten years,” Wadia conceded. “Whether that is much longer or shorter will depend on the amount of effort we invest today.”
Wadia explained that the main intention he and his colleagues have is to enter a dialog with the scientific community that might begin exploration into these materials. “Very few have had the same level of attention as silicon, CdTe and CIGS.”
“Thus far we have had tremendous support from this community, and there has been activity to look back to see if new techniques and knowledge can advance these materials.”
