(Bz)_n and (VBz)_n covalent functionalized MoS₂ monolayer: electronic and transport properties

Inspired by Benzene (Bz) derivatives dramatically enhancing MoS₂ monolayer electronic properties (ACS Nano. 2015, 9, 6018–6030), we have investigated electronic and transport properties of (Bz)_n/MoS₂ and (VBz)_n/MoS₂, which are designed by grafting (Bz)_n and (VBz)_n arrays onto 2D monolayer MoS₂ (ML-MoS₂), respectively, using density functional theory (DFT) and non-equilibrium Green's function (NEGF) methods. ML-MoS₂ provides a perfect substrate for grafting (Bz)_n and (VBz)_n arrays upon its surface as a result of stable covalent binding energy with −3.841 eV and −1.953 eV for (Bz)_n/MoS₂ and (VBz)_n/MoS₂ respectively. From the electronic properties, we can find that grafting (Bz)_n onto the ML-MoS₂ surface turns ML-MoS₂ from typical semiconductor to metallic properties because four wide bands coupled by (Bz)_n and MoS₂ in (Bz)_n/MoS₂ show better delocalization in heterointerface, resulting to these bands across the Fermi level (E _f). Furthermore, (VBz)_n nanowire grafted on the ML-MoS₂ further enhances the conductivities due to the introduction of metal V. Transport properties of ML-MoS₂, (Bz)_n/MoS₂ or (VBz)_n/MoS₂ for two-probe devices are all studied in zigzag and armchair direction. By comparison the zigzag direction is the preferential pathway for electron transport. The ferromagnetic (VBz)_n/MoS₂ shows a spin polarized transport characteristic, spin-down state gives a higher conductivity than spin-up state. Finally this work suggests that the novel (VBz)_n nanowire grafted on MoS₂ should have potential application in low-dimensional magnetic nanoelectronic devices. (paper)