Structural and optical characterization of V- and W-doped SnS2 thin films prepared by spray pyrolysis

Tin(IV) sulfide (SnS2) doped with V ions are promising intermediate band solar cell materials. In this work, we demonstrate the possibility of preparing thin films of Sn0.75V0.25S2 and Sn0.75W0.25S2 using the spray pyrolysis deposition method. Successful attempts are reported when a water/ethanol mixture at 9:1 ratio was used as a solvent and the deposition temperature was set at 360 °C. The samples were characterized by x-ray diffraction, atomic force microscopy, micro-Raman spectroscopy and UV–Vis–NIR optical transmission measurements. The analysis of the data showed that all the samples are crystalline with no impurities. Optical transmission data revealed that the direct and the indirect band gaps of SnS2 are found to be 2.25 and 2.15 eV, respectively. These values decrease as the samples were doped with V- and W-ions. The direct band gap values are found to fall within the 1.56–1.75 eV range while the indirect band gap values are found to be within the 1.55–1.70 eV range. Furthermore, the effect of doping caused the optical absorption coefficient to approximately be double of its values in a broad range extending from the visible to the near infrared regions. These findings suggest that Sn0.75V0.25S2 and Sn0.75W0.25S2 can be used as new potential solar energy absorbers in photovoltaic devices.