Paper NS-TuA12
SnS Nanoplates

Tuesday, November 8, 2016, 6:00 pm, Room 101D

Two dimensional (2D) layered materials such as graphene, metal dichalcogenides and black phosphorus are of increasing interest because of their unique electronic properties. Tin monosulfide (SnS) has the same crystal structure as black phosphorus. SnS may have potential applications in photovoltaics, photocatalysis, thermoelectrics, and batteries. We have synthesized 3-60 nm thick and up to approximately 10 micron wide SnS nanoplates via decomposition of tin(IV) diethyldithiocarbamate upon hot injection into oleylamine (300-340 ^oC). The reaction products are characterized using a combination of electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction (XRD), atomic force microscopy and Raman spectroscopy. All characterization techniques confirm that the final reaction product is orthorhombic SnS (e.g., after 60 minutes at 340 ^oC). At low temperatures (300 ^oC) and short synthesis times (1 minute) we also observe the presence of SnS₂ which suggests that decomposition of tin(IV) diethyldithiocarbamate first produces SnS_{2 .} Tin disulfide is subsequently reduced, likely by oleylamine, to SnS. Orthorhombic SnS grows preferentially as plates, with [010] direction normal to the plate surfaces. In fact, when plates are large (>1 micron) XRD from films cast from colloidal dispersions in toluene show predominantly the (040) diffraction. The SnS nanoplate sizes could be altered by controlling the temperature, oleylamine concentration, and reaction time. Nanoplate dispersions in toluene exhibit an optical absorption feature in the visible range of the electromagnetic spectrum, which we surmise to be of plasmonic origin. The nanoplate dispersions in toluene also respond to electric fields.