Two dimensional materials beyond MoS₂: Noble-transition-metal dichalcogenides

The structure and electronic structure of layered noble-transition-metal dichalcogenides MX₂ (M=Pt and Pd, and chalcogenides X=S, Se, and Te) have been investigated by periodic density functional theory (DFT) calculations. The MS₂ monolayers are indirect band-gap semiconductors whereas the MSe₂ and MTe₂ analogues show significantly smaller band gap and can even become semimetallic or metallic materials. Under mechanical strain these MX₂ materials become quasi-direct band-gap semiconductors. The mechanical-deformation and electron-transport properties of these materials indicate their potential application in flexible nanoelectronics.