Tuning the properties of SrI2: A DFT study on the contributions of S and Se doping

Strontium iodide (SrI₂) and S and Se doped variants of it were systematically investigated with the help of density functional theory (DFT), as it was implemented in WIEN2k using GGA-PBE approximation. Supercell of size 2 × 1 × 1 was adopted, which relates to the doping level of 12.5 %. The study targeted such properties as structural, electronic, optical, mechanical, and thermoelectric properties. Electronic band analysis identified direct band gap properties for pure and doped SrI₂, with the respective modified band gap values providing a take on doping in the electronic performance. The total density of states (TDOS) and partial density of states (PDOS) gave more understanding on the electronic behavior. Static refractive index of doped system has been increased up to 2.59 with respect to 2.25 of pristine SrI₂ by optical analysis. Bulk modulus, shear modulus, Young's modulus, B/G ratio as well as Poisson's ratio for mechanical characteristics were measured in order to determine the ductility and stiffness. At the 200–800 K range the thermoelectric calculations indicated an enhanced electrical conductivity and power factor in both S-doped and Se-doped SrI₂, which may have applications in energy.