Chalcogens' impurities and a single F-center in perovskite SrHfO3 compound: Ab initio calculations

The effects of Sulfur (S), Selenium (Se), or Tellurium (Te) doped SrHfO3 (SHO) on the electronic, optical and photocatalytic properties have been investigated using Density Functional Theory, taking into account the intrinsic F-center defect (Ov) in oxide materials. The findings showed that the substitution of oxygen atoms by chalcogens impurities decreased the forbidden band of SHO effectively. Furthermore, there is a huge improvement of the absorption coefficient in the visible spectrum when chalcogens' impurities meet an Ov defect in SHO, especially when 8.333% of S or Se meet an Ov in SHO (S/Se@OII + Ov) due to the shifting of the Fermi level to the lowest unoccupied molecular orbital which caused the n-type semiconductor behavior giving rise to the enhancement of carrier concentrations. Otherwise, the positions of the highest occupied molecular orbital and the lowest unoccupied molecular orbital respect the limits necessary to split water except for 12.5% of Se or Tedoped SHO (Se/Te@OIII), 8.333% of Te doped SHO with the presence of an Ov (Te@OII + Ov), and 12.5% of Se or Te doped SHO with an Ov defect (Se/Te@OIII + Ov) structures. In addition, the formation energy confirms that all studied structures are thermodynamically stables. We believe that our research will serve as a base for future studies on SHO to be used as semiconductors for photovoltaic and photocatalytic hydrogen production from water splitting applications.1.