Band nesting and the optical response of two-dimensional semiconducting transition metal dichalcogenides

We have studied the optical conductivity of two-dimensional (2D) semiconducting transition metal dichalcogenides using ab initio density functional theory. We find that this class of materials presents large optical response due to the phenomenon of band nesting. The tendency towards band nesting is enhanced by the presence of van Hove singularities in the band structure of these materials. Given that 2D crystals are atomically thin and naturally transparent, our results show that it is possible to have strong photon-electron interactions even in 2D.