Direct Synthesis of Two-Dimensional SnSe and SnSe₂ through Molecular Scale Preorganization

Abstract

Two-dimensional tin monoselenide (SnSe) and tin diselenide (SnSe2) materials were efficiently produced by the thermolysis of molecular compounds based on a new class of seleno-ligands. Main group metal chalcogenides are of fundamental interest due to their layered structures, thickness-dependent modulation in electronic structure, and small effective mass, which make them attractive candidates for optoelectronic applications. We demonstrate here the synthesis of stable tin selenide precursors by in situ reductive bond cleavage in the dimeric diselenide ligand (SeC2H4N­(Me)­C2H4Se)2 in the presence of SnCl4. New molecular precursors [SnIV(SeC2H4N­(Me)­C2H4Se)2], [SnIVCl2(SeC2H4N­(Me)­C2H4Se)], and [SnIV(SC2H4N­(Me)­C2H4S)­(SeC2H4N­(Me)­C2H4Se)] were thoroughly characterized by multinuclear magnetic resonance studies and single-crystal X-ray diffraction analysis that revealed the Sn­(IV) center to be octahedrally coordinated by two tridentate dianionic chelating ligands or trigonally pyramidally coordinated by one chelating ligand and two chlorido ligands. Preorganization of metal–selenium bonds in both compounds offered direct and reproducible synthetic access to two-dimensional tin chalcogenides (SnSe and SnSe2) via simple adjustment of the pyrolysis temperature. Additionally, SnSe2 and SnS x Se2–x particles could be successfully synthesized by microwave-assisted decomposition of the molecular precursors, which was unambiguously corroborated by both experimental and computational analyses that explained the formation of a selenium rich SnS x Se2–x phase from a single molecular precursor containing both Sn–Se and Sn–S bonds.

Single-crystalline WSe2 nanoflakes as efficient electrocatalysts

“…The initial selenium containing ligand was synthesized following an optimized synthesis route established by Hartl et al to isolate the air stable crystalline ligand [{(SeC 2 H 4 ) 2 NMe} 2 ]. 28…”

“…The W–Se precursor belongs to a precursor class containing a chelating tridentate, dianionic chalcogenolate-ligand [( − XC 2 H 4 ) 2 NMe] (X = S, Se) in combination with M 2+ or M 4+ centers ([M IV {(XC 2 H 4 ) 2 NMe} 2 ] or [M II (XC 2 H 4 ) 2 NMe], respectively with X = S, Se and M IV = Ti, Zr, Hf, Mo, W, Sn, M II = Sn). 27–29 This unique precursor class, known for a well-defined decomposition pathway and good solubility in organic solvents, offers a new synthetic access to phase-pure crystalline WSe 2 from a single molecular source. 9,30 The results emphasize the need for carefully designed molecular precursors and optimized decomposition parameters to achieve high-quality, well-defined structures of WSe 2 for harnessing the anisotropic properties of layered TMDCs.…”

Synthesis and theoretical study of a mixed-ligand indium(iii) complex for fabrication of β-In2S3 thin films via chemical vapor deposition

“…This is possible due to lower decomposition temperature as residual carbon decomposes generally at higher temperatures (>500 °C). 11 The presence of oxygen may be inevitably caused by sample handling contamination or surface oxidation during or after the CVD experiment, respectively.…”

“…9,10 Metal-ligand (M-S(Se)-R) interactions play a deterministic role in the formation of metal sulfides and selenides. 11,12 Gas-phase chemistry offers a unique opportunity to study the intrinsic reactivity of chemical species. 13 The metal-thiolate bonds can be strongly covalent, and involve different orbital interactions.…”

[(Ph3P)2Ag(μ-SeCH2Ph)2In(SeCH2Ph)2]: a new heterobimetallic single source precursor as a springboard to bulk, nano and thin film ternary AgInSe2 materials

“…For instance, Austin et al have synthesized bulk AgInSe 2 from the constituent elements in sealed evacuated silica tubes at very high temperature. 14 Other methods include hydrothermal synthesis, 15 pulse laser vaporization, 16,17 thin film deposition by flash evaporation 18 and RF magnetron sputtering, etc. 19 In contrast, the solution phase soft-chemical route has always been adored over these conventional syntheses because it is fast, requires low temperature and is cost effective.…”