Synthesis, Internal Structure, and Formation Mechanism of Monodisperse Tin Sulfide Nanoplatelets

Abstract

Tin sulfide nanoparticles have a great potential for use in a broad range of applications related to solar energy conversion (photovoltaics, photocatalysis), electrochemical energy storage, and thermoelectrics. The development of chemical synthesis methods allowing for the precise control of size, shape, composition, and crystalline phase is essential. We present a novel approach giving access to monodisperse square SnS nanoplatelets, whose dimensions can be adjusted in the range of 4-15 nm (thickness) and 15-100 nm (edge length). Their growth occurs via controlled assembly of initially formed polyhedral seed nanoparticles, which themselves originate from an intermediate tetrachlorotin-oleate complex. The SnS nanoplatelets crystallize in the α-SnS orthorhombic herzenbergite structure (space group Pnma) with no evidence of secondary phases. Electron tomography, high angle annular dark field scanning transmission electron microscopy and electron diffraction combined with image simulations evidence the presence of ordered Sn vacancy rich (100) planes within the SnS nanoplatelets, in accordance with their slightly S-rich composition observed. When using elemental sulfur instead of thioacetamide as the sulfur source, the same reaction yields small (2-3 nm) spherical SnS2 nanoparticles, which crystallize in the berndtite 4H crystallographic phase (space group P3m1). They exhibit quantum confinement (E(g) = 2.8 eV vs 2.2 eV in the bulk) and room temperature photoluminescence. By means of electrochemical measurements we determined their electron affinity EA = -4.8 eV, indicating the possibility to use them as a substitute for CdS (EA = -4.6 eV) in the buffer layer of thin film solar cells.

Optical and Structural Properties of Tin Sulfide Nanoparticles Obtained via Solvothermal Routes

“…The synthesis of tin sulfide nanoparticles via the solvothermal decomposition of single source precursor compounds is not widely reported in literature compared to other routes such as wet chemical route, modified solution dispersion method, and physical deposition methods. Kergommeaux et al have synthesized tin sulfide nanoplatelets using the colloidal method of synthesis, which involved Tin(IV) chloride pentahydrate, and thioacetamide as the tin and sulfur precursors respectively in oleylamine . Furthermore, tin sulfide obtained via a modified solution dispersion involving the direct dispersion of melted tin in a sulfur‐dissolved solvent has been reported …”

“…Kergommeaux et al have synthesized tin sulfide nanoplatelets using the colloidal method of synthesis, which involved Tin(IV) chloride pentahydrate, and thioacetamide as the tin and sulfur precursors respectively in oleylamine. [11] Furthermore, tin sulfide obtained via a modified solution dispersion involving the direct dispersion of melted tin in a sulfur-dissolved solvent has been reported. [9] ] Solvothermal method via single source decomposition involves the decomposition of a single source precursor in high boiling point solvents at a temperature beyond the stability of the compound.…”

Colloidal tin sulfide nanosheets: formation mechanism, ligand-mediated shape tuning and photo-detection

“…tin(IV) tetrachloride pentahydrate, tin(II) chloride) or with the assistance of hexamethyldisilazane (HMDS) for 2D nanomaterial formation. 16,[29][30][31] The colloidal synthesis of 2D SnS NSs in the here presented work uses tin(II) acetate as tin precursor, which can be partly converted into the corresponding Sn-oleate complex during the conditioning step in the presence of oleic acid and partly serving as ligand for NS formation.…”

Facile Formation of Nanodisk‐Shaped Orthorhombic SnS Layers from SnS2 Particles for Photoelectrocatalytic Hydrogen Production

“…[19] Such diverse applicationso fS nS layers reflect the inherentf unctional richness of the SnS layers such as 2D anisotropic optical, electrical and thermoelectric properties of SnS [5,6,10,20] as has been experimentally determinedf rom the thickness, angle, and temperature-dependent Raman characteristics. [5,21] Various functional devices employing 2D SnS materials have been prepared using chemical routes [10,[22][23][24][25][26][27][28] as well as vacuum routes. [5,9,15,17,21,29] For example, liquid-phase exfoliated bilayer SnS nanosheets from ac ommercial SnS material are showed to have at unable band gap at 1-2.5 eV by as imple size selection.…”