Effect of Indium and Antimony Doping on SnS Photoelectrochemical Solar Cells

Single crystals of pure SnS, indium (In) and antimony (Sb) doped SnS are grown by the direct vapor transport technique. Two doping concentrations of 5 at.% and 15 at.% are employed for both In and Sb dopants. In total, five samples are studied, i.e., pure SnS, 5 at.% In-doped SnS, 15 at.% In-doped SnS, 5 at.% Sb-doped SnS and 15 at.% Sb-doped SnS single crystals. The energy dispersive analysis of x-ray (EDAX) and x-ray diffraction (XRD) analysis show that all the five as-grown single crystal samples possess near perfect stoichiometry and orthorhombic structure, respectively. The doping of In and Sb in SnS is established from the EDAX data and from the shift in the peak positions in XRD. Photoelectrochemical (PEC) solar cells are fabricated by using the as-grown single crystal samples along with iodine/iodide electrolytes. Mott–Schottky plots for different compositions of iodine/iodide electrolytes show that 0.025 M I₂+1 M NaI+2 M Na₂SO₄+0.5 M H₂SO₄ will be the most suitable electrolyte. Study of efficiency (η) and fill factor for different intensities of illuminations at room temperature is carried out for the five samples. The In-doped SnS single crystals show better PEC efficiency than the undoped and Sb-doped SnS single crystals.