Formula SnS Density 5.22 g/cm³ | Molar mass 150.76 g/mol Appearance dark brown solid | |
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Tin(II) sulfide is a chemical compound of tin and sulfur. The chemical formula is SnS. Its natural occurrence concerns herzenbergite, a rare mineral.
Contents
Synthesis
Tin(II) sulfide can be prepared by reacting tin with sulfur, or tin(II) chloride with hydrogen sulfide.
Sn + S → SnS SnCl2 + H2S → SnS + 2HClProperties
Tin(II) sulfide is a brown solid, insoluble in water, but soluble in concentrated hydrochloric acid. Tin (II) sulfide is soluble in (NH4)2S. It has a layer structure similar to that of black phosphorus. As per black phosphorus, tin(II) sulfide can be ultrasonically exfoliated in liquids to produce atomically thin semiconducting SnS sheets that have a wider optical band gap (>1.5 eV) compared to the bulk crystal.
Photovoltaic Applications
Tin(II) sulfide is currently one of the leading candidates for absorber layers in next generation thin film solar cells. Currently, both Cadmium Telluride and CIGS (Copper Indium Gallium Sulfide) are used as p-type absorber layers, but they are formulated from toxic, scarce constituents. Tin(II) sulfide, by contrast, is formed from cheap, earth abundant elements, and is nontoxic. This material also has a high optical absorption coefficient, p-type conductivity, and a mid range direct band gap of 1.3-1.4 eV, required electronic properties for this type of absorber layer. In fact, the energy conversion efficiency of tin(II) sulfide is projected to be 32%, comparable to crystalline silicon. Finally, Tin(II) sulfide is stable in both alkaline and acidic conditions. All aforementioned characteristics suggest tin(II) sulfide as an optimal material for solar cells.
At present, tin(II) sulfide thin films for use in photovoltaic cells are still in the research phase of development. Barriers for use include a low open circuit voltage and an inability to realize many of the above properties due to challenges in fabrication, but tin(II) sulfide still remains a promising material once technical challenges are overcome.