First-Principles Comparative Study of CuFeSe2 and CuFeS2

In this paper, on the basis of first-principles, the CASTEP module of Materials Studio is used to calculate the band structures and optical properties of CuFeSe 2 and CuFeS 2 under the PBE pseudopotential of the generalized gradient approximation (GGA). The calculated results show that both CuFeSe 2 and CuFeS 2 are direct bandgap semiconductors with forbidden band widths of 0.64 eV and 1.06 eV, respectively. In the visible light range, the highest absorption coefficient of CuFeSe 2 is 1.082×10 5 cm -1 , the average reflectivity is 0.52, the maximum conductivity is 7.23 fs -1 , the electrostatic constant is 65.9; the maximum value the highest absorption coefficient of CuFeS 2 is 0.872×10 5 cm -1 , the average reflectivity is 0.44, the maximum conductivity is 4.44 fs -1 , the static dielectric constant is 52.32. The calculation results in this paper show that compared with CuFeS 2 , CuFeSe 2 has advantages in photoconductivity and carrier separation, but has disadvantages in band gap and reflectivity. It is recommended to combine the two materials to prepare tandem solar cells.