The investigation of crystal structure, elastic and optoelectronic properties of CuSbS2 and CuBiS2 compounds for photovoltaic applications

The crystal structures, electronic, elastic and optical properties of the ternary compounds CuSbS2 and CuBiS2 have been investigated by using the full-potential linear augmented plane wave (FP-LAPW) method. From this study, it is found that the compounds CuSbS2 and CuBiS2 have indirect band gap energies which are calculated with the mBJ potential as 1.28 and 1.05 eV, respectively. CuSbS2 crystallizes in an orthorhombic structure, with the Pnma space group, the lattice parameters are a = 6.018 Å, b = 3.795 Å and c = 14.495 Å, CuBiS2 has also an orthorhombic structure, with the space group Pnma and the lattice parameters a = 6.134 Å, b = 3.911 Å and c = 14.548 Å, which are used in our calculations. Optical parameters, such as dielectric constant, refractive index and reflectivity are calculated and analyzed. Elastic properties are also investigated for the first time. The results demonstrated that the compounds CuSbS2 and CuBiS2 have the potential to be used for photovoltaic applications.