Effect of C4H6O6 concentration on the properties of SnS thin films for solar cell applications

SnS thin films were prepared by chemical bath deposition using an environmentally friendly and economic complexing agent, tartaric acid (C₄H₆O₆) with different concentrations. X-ray diffraction analysis confirmed that all the deposited films exhibited polycrystalline nature with a predominant plane of (1 1 1) related to an orthorhombic structure. The intensity of the (1 1 1) plane increased with increasing concentration of the complexing agent. Raman spectra of the films showed the characteristic vibrational modes at 94, 160, 191, and 217 cm⁻¹, corresponding to orthorhombic SnS. SEM micrographs showed homogeneous surfaces with the presence of nut-shaped grains. The optical absorption coefficient for the prepared films was >10⁴ cm⁻¹, representing that the deposited films showed high absorption. Electrical studies revealed the p-type conducting nature of the deposited films. The SnS solar cell fabricated with a tartaric acid concentration of 1.2 M showed the highest efficiency of 1.62% with an open-circuit voltage of 0.283 V, a short-circuit current density of 13.9 mA cm⁻², and a fill factor of 41.1%.