For solar energy to become an economically viable energy source, alternative semiconductor materials to be used in solar cells must be found. Silicon, the longtime standard for solar cells, is expensive to process and in ever-growing demand. Thin films made of CdTe (cadmium telluride) and CIGS (copper indium gallium selenide) have potential, but their raw material sources are too limited to meet the world’s growing energy needs.
One promising alternative is iron pyrite (FeS2), the most abundant compound on the earth’s surface. Iron pyrite is easily mined, nontoxic and demonstrates good absorption qualities. The viability of iron pyrite for photovoltaics depends on finding a means of processing the material for use as a thin film.
Cyrus Wadia and Yue Wu of Berkeley Lab have invented a method of synthesizing pyrite nanocrystals from a solution heated under pressure. The synthesized pyrite particles created were determined to be pure phase crystalline pyrite through testing with powder x-ray diffraction, x-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy. The Berkeley Lab method has been shown to work for a variety of solution compositions heated at a range of temperatures and pressures.