Anisotropic transport and optical birefringence of triclinic bulk and monolayer NbXY(X = S, Se and Y = Cl, Br, I).

A systematic analysis of the electronic, thermoelectric and optical properties of triclinic van der Waal's solids NbXY(X = S, Se and Y = Cl, Br, I) is carried out within the framework of density functional theory for bulk and monolayer. The investigated compounds are semiconductors in bulk and monolayer, with band gap values ranging from 1.1 to 1.