First-principles calculations to investigate impact of doping by chalcogen elements on the electronic, structural, and optical properties of SrTiO3 compounds

Abstract

Doping techniques are commonly utilized to effectively modify the physical properties of a desired compound. In this study, we employed the first-principles DFT calculations with a GGA + TB-mBJ approach as implemented by the Wien2k code, by investigating the effects of oxygen group element concentrations on the structural, electronic, and optical properties of the perovskite substance SrTiO3. We calculated the formation energies of each doped structure to assess the viability of synthesis. The band gap is equal to 1.355 eV, 0.653 eV, and 0.632 eV for 12.5 % S, Se, and Te doped SrTiO3, respectively. For the pure SrTiO3, the band gap is 2.584 eV. According to our findings, raising the chalcogen concentrations resulted in a considerable decrease in band gaps and an improvement in the ability to absorb light in the visible range (380–790 nm), exceeding 105 cm−1 for Te doped SrTiO3 (STO). At zero frequency, the dielectric constant was found (ε1 (0)) to be 4.432 for SrTiO3 pure and 6.332 for SrTiO3 doped with Te (12.5 %) in GGA-PBE and (ε1 (0)) = 4.432 and 12.217 for GGA + mBJ. The optical conductivity of SrTO3 doped with Te is determined to be 0.322 * 104 /Ω.cm, in comparison to a value of 0.377 * 104/Ω.cm for mBJ. Our research revealed that raising the chalcogen concentrations significantly enhanced the electrical conductivity, as predicted, along with improvements in optical conductivity and reflectivity. SrTiO3-xYx (Y = S, Se, or Te) represents one of our quaternary alloys, demonstrating substantial potential as a promising material for advanced photovoltaic and solar cell applications. Our findings revealed that the doped materials exhibited significantly high absorption rates and productivity. We also examined additional optical parameters, including optical band gap, Urbach energy, and optical conductivity.