Iodine-based triple halide perovskites for photovoltaic and photocatalytic applications: a ab-initio study

The switch to sustainable power generation sources has gained substantial spotlight due to the essential need to decrease fossil fuels dependence, and alleviate climate change issues. This research aims to explore the first principle calculations for geometrical structure, enthalpy of formation, electronic structure behavior, optical spectra, and photocatalytic performance of the clean new Iodine-based triple perovskite compounds A3B2I9 (A = Rb or Cs, and B = Sb or Bi) using FP-LAPW method based on the density functional theory implemented in Wien2K software. The outcomes prove that these triple perovskite compounds can be formed spontaneously under standard conditions, because they are thermodynamically stable. Moreover, the electronic band structure shows an indirect semiconductor behavior of all studied compounds. Further, the optical spectra highlights that all studied compounds have high visible light absorption due to their suitable forbidden band values [1.8 eV-2.369 eV] which facilitate efficient electron-hole pairs generation maximizing the conversion of light into electrical energy. In addition, all studied compounds are satisfied the limits necessary to split water and then to produce hydrogen. Consequently, these compounds are most likely to be used as Lead-free perovskites in various optoelectronic applications, especially solar cells and hydrogen production from water splitting.