Study of physical properties of Lead-Free metal halide perovskite compounds CsMI3(M=Mg,Ga) for solar cells applications by Ab-Initio simulations.

Abstract

The primary objectives are to thoroughly examine the CsMI3 (M = Mg, Ga) lead-free perovskite materials for photovoltaic and optoelectronic applications using first-principle calculations. This study observed the mechanical, electrionic, optical, thermal, and structural aspects while also verifying the stability of the cell. The calculated results are compared with experimentally synthesized similar perovskite compound CsPbI3. The computed formation energies of the compounds as follows: CsMgI3(-1.81 eV/atom)  CsPbI3(-1.624 eV/atom)  CsGaI3(-1.326 eV/atom) and negative results are represented the mechanically stability of the compounds. Since there was no negative frequency, the phonon research demonstrated the compound’s dynamic stability. The computed  values support the CsMI3 (M= Pb, Ga) compounds possess pure ductility, whereas the CsMgI3 compounds lie on the ductile-brittle transition line. The bandgap (Eg) is calculated and found to be in the range of 1.63 to 3.26 eV that makes them potential candidate to be used as absorbance materials in solar cell applications. The Eg is further tuned to achieve more appropriate range for the solar cell applications by doping into the CsMg(I1-xBrx)3 where x = (0, 0.25, 0.50, 0.75, 1). The Eg is found to be 1.12 to 1.87 eV and  increase due to doping that makes them more apposite for the suggested range of absorbance materials in the solar cell. The best combination CsMg(I0.75Br0.25)3 shows Eg  1.4 eV that is well agreement with the optimum band gap suggested the Shockley-Queisser limit in a single layer solar cell absorbance material to be shown highest efficiency.