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Molecular Routes to Two-Dimensional Metal Dichalcogenides MX2 (M = Mo, W; X = S, Se)

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journal contribution
posted on 16.07.2019 by Veronika Brune, Corinna Hegemann, Sanjay Mathur
New synthetic access to two-dimensional transition metal dichalcogenides (TMDCs) is highly desired to exploit their extraordinary semiconducting and optoelectronic properties for practical applications. We introduce here an entirely novel class of molecular precursors, [MIV(XEtN­(Me)­EtX)2] (MIV = MoIV, WIV, X = S, Se), enabling chemical vapor deposition of TMDC thin films. Molybdenum and tungsten complexes of dianionic tridentate pincer-type ligands (HXEt)2NR (R = methyl, tert-butyl, phenyl) produced air-stable monomeric dichalcogenide complexes, [W­(SEtN­(Me)­EtS)2] and [Mo­(SEtN­(Me)­EtS)2], displaying W and Mo centers in an octahedral environment of 4 S and 2 N donor atoms. Owing to their remarkable volatility and clean thermal decomposition, both Mo and W complexes, when used in the chemical vapor deposition (CVD) process, produced crystalline MoS2 and WS2 thin films. X-ray diffraction analysis and atomic-scale imaging confirmed the phase purity and 2D structural characteristics of MoS2 and WS2 films. The new set of ligands presented in this work open ups convenient access to a scalable and precursor-based synthesis of 2D transition metal dichalcogenides.