Nanostructured SnS1−xTex thin films: Effect of Te concentration and physical properties

• SnS1−xTex thin films were prepared by electrodeposition method on FTO glass substrates.
• The XRD patterns obviously showed that the synthesized film was polycrystalline.
• The UV–Vis shows a variation in the optical band-gap energy of SnS1−xTex films from 1.28 to 1.44 eV.
• SnS1−xTex films would be suitable for the absorber layers in solar cells.
• The solar cell based on Te-doped SnS has higher conversion efficiency compared with SnS solar cell.

Nanostructured Te-doped SnS thin films (SnS1−xTex, x = 0.0, 0.020, 0.027, 0.032, 0.036) were deposited on fluorine doped tin oxide (FTO) substrate from aqueous solution containing 2 mM SnCl2 and 16 mM Na2S2O3 and various amounts of 5 mM TeO2 solution. The pH, temperature, time, and deposition potential (E) of the solution were kept at 2.1, 60 °C, 30 min and −1 V, respectively. The deposited films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence (PL) and UV–Vis. XRD patterns obviously indicated that the synthesized films were polycrystalline with orthorhombic structure and by increasing the amount of Te concentration, the crystallinity was decreased. The FESEM images showed that the morphology of the nanostructures was changed with increasing Te content. PL and UV–Vis analysis were used to investigate the optical properties of materials. The PL spectra showed a red shift with increasing of Te concentration. The UV–Vis spectra showed that the optical bandgap energy decreased from 1.44 to 1.28 eV with an increase in the Te concentration. Solar cell devices were assembled using the deposited films as working electrodes and FTO as the counter electrodes. The conversion efficiency of solar cell based on SnS with Te-doping was increased compared with the SnS without Te-doping solar cell.