Quasiparticle band-edge energy and band offsets of monolayer of molybdenum and tungsten chalcogenides

We report the quasiparticle band-edge energy of monolayer of molybdenum and tungsten dichalcogenides, MX2 (M = Mo, W; X = S, Se, Te). Beyond calculating bandgaps, we have achieved converged absolute band-edge energies relative to the vacuum level. Compared with the results from other approaches, the GW calculation reveals substantially larger bandgaps and different absolute quasiparticle energies because of enhanced many-electron effects. Interestingly, our GW calculations ratify the band-gap-center approximation, making it a convenient way to estimate band-edge energy. The absolute band-edge energies and band offsets obtained in this work are important for designing heterojunction devices and chemical catalysts based on monolayer dichalcogenides. (C) 2013 AIP Publishing LLC.