Iron pyrite is an attractive candidate for PVs as it is non-toxic, naturally abundant and requires relatively low cost extraction methods [1]. It has even been calculated that the entirety of the US’ electric energy needs could be met by using existing waste FeS2 from mining in solar cells with an efficiency as low at 10% [2].
In the pyrite crystal structure, FeS2 exhibits excellent absorption properties for integration in a photovoltaic device. The 0.95 eV indirect bandgap places FeS2 near the peak on the Shockley–Queisser graph for single-junction efficiency limit, a commonly used measure for predicting a material’s suitability for solar energy conversion. The nano scale has the potential to reduce material needs. Iron pyrite’s large absorption coefficient, up to 6 x 105 cm-1, and comparatively longer diffusion length should minimize electron-hole recombination. FeS2 shows extended red light absorption [3], which can increase the efficiency of a solar device.
The figure above, taken from [1], illustrates the potential impact FeS2 could have on the photovoltaic industry.
[1] Alharbi F, Bass JD, Salhi A, Alyamani A, Kim HC, Miller RD. Abundant non-toxic materials for thin film solar cells: Alternative to conventional materials. Renewable Energy 2011.
[2] Pasquarelli R, Curtis C, Van Hest M. Inkjet printing of Nickel and Silver Metal Solar cell contacts.
[3] Lin, Y. Y., Wang, D. Y., Yen, H. C., Chen, H. L., Chen, C. C., Chen, C. M., Tang, C. Y.; Chen, C. W. Nanotech. 2009, 20, 405207.