Fabrication of Cu2SnS3 thin films by sulfurization of evaporated Cu-Sn precursors for solar cells.

The ternary compound semiconductor Cu₂SnS₃ (CTS) is formed from non-toxic materials that are abundant in Earth's crust and other low-cost elements. CTS has also been reported to a band gap energy range of 0.93-1.77 eV and an absorption coefficient of 1.0×10⁴ cm^-1. Consequently, CTS is a potential material for the p-type absorber layer of thin film solar cells. In this study, we examined the dependence of the optical, electrical and photovoltaic properties of CTS thin films on the Cu/Sn composition ratio. CTS thin films were fabricated by sulfurizing evaporated Cu-Sn precursors with different Cu/Sn composition ratios at 560 °C for 2 h in a N² atmosphere and sulfur vapor. The Cu/Sn composition ratios of the sulfurized films were determined to be 1.6-2.5 by X-ray fluorescence. The solar cell comprising a CTS thin film with a Cu/Sn composition ratio of 1.77 exhibited the best performance among the cells examined, an open-circuit voltage of 242 mV, a short-circuit current density of 28.9 mA/cm², a fill factor of 41.7% and a conversion efficiency of 2.92% were obtained. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]