New routes to sustainable photovoltaics:: evaluation of Cu2ZnSnS4 as an alternative absorber material

Thin film heterojunction solar cells based on chalcopyrites such as Cu(In, Ga)Se-2 have acheived impressive efficiencies. However concern about the long term sustainability of photo-voltaics based on scarce or expensive raw materials has prompted the search for alternative absorber materials. In this work, films of the p-type absorber Cu2ZnSnS4 (CZTS) were prepared by electroplating metallic precursors sequentially onto a molybdenym coated glass substrate followed by an nealing in a sulfur atmosphere. The polycrystalline CZTS films were characterized by photoelectrochemical methods, which showed films were p-type with doping densities of the order of 10(16) cm(-3) and a band gap of 1.49 eV, close to the optimum value for terrestrial solar energy conversion. Preliminary results obtained for solar cells fabricated with this material are promising. (c) 2008 WILEY-VCH Verlag GmbH & Co. KgaA, Weinheim.