Cu2ZnSnS4 solar cells grown by sulphurisation of sputtered metal precursors

Cu2ZnSnS4 (CZTS) thin films were grown with a two-step process. Metal precursors deposited on Mo-coated soda lime glasses by RF sputtering were sulphurised by thermal treatment in sulphur vapours. To optimise the growth process, comprehensive structural characterisation (by electron microscopy, Raman spectroscopy and X-ray diffraction) of the CZTS films was mandatory. The results are reported and discussed herein. Of the many stoichiometries obtained by sulphurisation, Cu-poor/Zn-rich CZTS films were chosen as absorber layers to be tested in photovoltaic devices in order to prevent development of the Cu2 −xS secondary phase typical of Cu-rich samples. Electrical characterisation of these CZTS solar cells demonstrates efficiency around 4%.