Investigation of structural and luminescence properties of nanocrystalline tungsten-incorporated molybdenum disulphide ternary compounds: an experimental and DFT study

摘要

The present manuscript reports the synthesis of tungsten-incorporated molybdenum disulphide ternary compounds in particle form at the nanoscale using existing solid state reactions, followed by ultrasonication and a densityfunctional theory (DFT) investigation of the compound system. The effect of W in the W-inserted MoS$_2$ ternary compound system is the subject of current research. A comparative study shows enhanced photoluminescence (PL) at room temperature in the as-synthesized transition metal dichalcogenide (TMD) ternary compound. The compositional and structural characterization studies of the materials are performed using XRD, SEM, EDX, TEM and Raman spectroscopy. We have observed that a combination of W and S leads to better crystallinity than the combination of Mo and S in the compound system. The high band gap (BG) energy also confirms the nanoscale dimension of the material system which may be attributed to the formation of excitonic states from spin splitting and band nesting effects. A theoretical investigation of the effect of Win the MoS$_2$ system using DFT also reveals that insertion of Wleads the system toward a direct BG semiconductor (SC). Multiple BGs of the material in the visible light range as found by UVa??Visible (UVa??Vis) spectroscopy, suggest applicability of these materials in luminescence devices and photocatalytic activity.