Not your familiar two dimensional transition metal disulfide: structural and electronic properties of the PdS₂ monolayer

By means of density functional theory (DFT) computations, we theoretically investigated a novel two-dimensional (2D) transition metal disulfide (TMD), namely the PdS₂ monolayer. Distinguished from other 2D TMDs which adopt the ordinary 2H or 1T configuration, the PdS₂ monolayer presents rather unique structural properties: each Pd atom binds to four S atoms in the same plane, and two neighboring S atoms can form a covalent S–S bond. The hybrid HSE06 DFT computations demonstrated that the PdS₂ monolayer is semiconducting with an indirect band gap of 1.60 eV, which can be effectively reduced by employing a uniaxial or biaxial tensile strain. Especially, PdS₂ has rather large hole and electron mobilities. Our results suggest that the PdS₂ monolayer is rather promising for future electronics and optoelectronics.