Thin film solar cells have reached commercial maturity and extraordinarily high efficiency that make them competitive even with the cheaper Chinese crystalline silicon modules. However, some issues (connected with presence of toxic and/or rare elements) are still limiting their market diffusion. For this reason new thin film materials, such as Cu₂ZnSnS₄ or SnS, have been introduced so that expensive In and Te, and toxic elements Se and Cd, are substituted, respectively, in CuInGaSe₂ and CdTe. To overcome the abundance limitation of Te and In, in recent times new thin film materials, such as Cu₂ZnSnS₄ or SnS, have been investigated. In this paper we analyze the limitations of SnS deposition in terms of reproducibility and reliability. SnS deposited by thermal evaporation is analyzed by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and atomic force microscopy. The raw material is also analyzed and a different composition is observed according to the different number of evaporation (runs). The sulfur loss represents one of the major challenges of SnS solar cell technology.

Tin sulfide is one of the most promising alternative materials for photovoltaic. One main requirement for enhancing device efficiency is high quality SnS thin films. We present our study of recrystallization of SnS thin film by post deposition treatment at high temperature with KI and SnCl₂. A recrystallization of SnS was achieved with both KI and SnCl₂, but it has been observed that this phenomenon occurs only when SnS film is deposited at high temperature, whereas for low temperature-SnS film the treatment process produces a mix of secondary phases into the SnS matrix.