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

Abstract

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 (Rct) through the film. Finally, the improved PEC performance highlights the application of SnS2 photoanode in PEC cell.