Using first principles calculations, we predicted that a direct-band-gap between 0.98 and 2.13 eV can be obtained in silicene by symmetrically and asymmetrically (Janus) functionalisation with halogen atoms and applying elastic tensile strain.
Two new graphene allotropes, penta-graphene and phagraphene, have been proposed recently with unique electronic properties,e.g.quasi-direct band gap, direction-dependent Dirac cones and tunable Fermi velocities.
We have investigated the effect of uniform plane strain on the electronic properties of monolayer 1T-TiS2using first-principles calculations. With the appropriate tensile strain, the material properties can be transformed from a semimetal to a direct band gap semiconductor.