Band gaps of the solar perovskites photovoltaic CsXCl3 (X=Sn, Pb or Ge)

In this work, we are studying structural and electronic properties of the solar perovskites photovoltaic CsXCl3 (X = Sn, Pb or Ge) using the ab-initio calculations under the Quantum Espresso package. The total and partial density of states (DOSs) have been elaborated and discussed for each material: CsSnCl3, CsPbCl3 and CsGeCl3. On the other hand, the band structure of each one of these materials has been established. It is found that these materials exhibit a non-magnetic and semi-conductor behavior. The dependency of the band gap of the solar perovskites photovoltaic CsXCl3 (X = Sn, Pb or Ge) is illustrated as a function of the lattice parameter 'a' (angstrom). It is found that when increasing the lattice parameter the band gap increases for all the materials: CsSnCl3, CsPbCl3 and CsGeCl3. In addition, for a fixed value of the lattice parameter 'a' the band gap increases when we move from one material to another: CsSnCl3, CsGeCl3 and CsPbCl3, respectively. To complete this study, we have inspected the effect of the spin orbit coupling (SOC) correction on the band gap energy of the different solar perovskite materials CsXCl3 (X = Sn, Pb or Ge), when using the optimized lattice parameter values. Our results revealed that the (SOC) effect is to decrease the band gap energy values of the three studied solar perovskite materials.