Electronic and vibrational properties of defective transition metal dichalcogenide Haeckelites: new 2D semi-metallic systems

The electronic properties of monolayered Haeckelites constructed from transition metal dichalcogenides (TMDs) such as MoS2, WS2, WSe2 and MoSe2, have been studied by first principles calculations. It was found that monolayered Haeckelites exhibit a semi-metalic behavior, whereas the traditional monolayered TMDs show a direct band gap, which is characteristic of semiconducting TMDs. Furthermore, metallic TMD monolayers of NbS2 or NbSe2 transform into direct and indirect gap semiconductors, respectively when arranged into Haeckelite geometries. The vibrational properties and Raman spectra of NbS2 Haeckelites were also calculated.