Investigating the light harvesting capacity of sulfur ion concentration dependent SnS₂ thin films synthesized by self-assembled arrested precipitation technique

In the present report, we have successfully synthesized sulfur ion concentration dependent SnS₂ thin films using energy efficient, low cost and self-assembled arrested precipitation technique (APT). The influence of sulfur ion concentration on the crystallinity, optical tuning, surface morphology and photoconversion efficiency of SnS₂ thin films was studied thoroughly. Optical absorption studies confirm a red shift in the absorption edge, which asserts its application as photoactive material. X-ray diffraction (XRD) and Raman studies confirmed the SnS₂ thin film corresponds to the hexagonal crystal phase with preferential orientation along (001) plane, further the compositional analysis was verified by Energy dispersive x-ray (EDS) and x-ray photoelectron spectroscopy (XPS) studies. SEM images clearly highlight the transformation of surface morphology from nanospheres to compact interconnected nanograins with an increase in sulfur ion concentration; also HRTEM image confirms the formation of aggregated nanograins. Moreover, the diffraction rings in the SAED pattern suggest the hexagonal SnS₂ structure which corroborates well with the XRD data. SnS₂ as photoanode exhibits good photoelectrochemical (PEC) performance in I^-/I₃ ^- redox electrolyte. Synthesized SnS₂ thin films showed a significant enhancement in photocurrent conversion efficiency (0.09%) among reported values. Thus, sulfur ion concentration variation has the ability to alter the PEC performance of SnS₂. Electrochemical Impedance Spectroscopy (EIS) study was used to analyze the charge transfer resistance (R_ct) through the film. Finally, the improved PEC performance highlights the application of SnS₂ photoanode in PEC cell.