Optical linear-nonlinear and dispersion parameters of thermally evaporated SnS thin films as absorber material for solar cells

In this manuscript, we report the results of optical properties of SnS thin films, deposited on FTO coated glass substrates at room temperature by thermal evaporation technique. In addition, the effect of film thickness on the optical behavior of FTO/SnS is analyzed and obtained results are compared with data of SnS films grown on glass and ITO substrates. Our study indicates that the properties of SnS film are independent of the substrate material. Further, the influence of the film thickness on the other optical parameters including, linear and third order nonlinear optical constants and dispersion parameters have also been investigated using the transmission, reflection, and absorption spectra. It is found that the optical band gap decreases from 2.07 to 1.30 eV with increase in SnS film thickness, whereas the refractive index increases with increasing thickness. Additionally, the oscillator energy, and the dispersion energy are estimated using WempleDiDomenico approach. The dispersion energies are in the range of 7.20 to 4.59 eV, while the oscillator energies of the thin films are in the range of 5.49 to 2.24 eV. Moreover, the nonlinear refractive index, and optical susceptibility are calculated by using the empirical relation of Tichy and Ticha. The volume of data suggests optical properties of SnS thin films are strongly dependent on film thickness.
Comment: 24 pages, 11 figures