Study of the effect of V-doping on the opto-electrical properties of spray-pyrolized SnS thin films

SnS is an earth-abundant material that is a potentially suitable candidate for the absorber layer in solar cells. Here spray-pyrolized SnS thin films doped with vanadium were studied using structural and opto-electrical methods. The thin films have an orthorhombic structure with a preferential (111) crystallographic direction. SnS has an indirect bandgap of around 1.05 eV, whereas doping with vanadium changes the band edge and shifts the absorption threshold to around 1.2 eV. The photoluminescence study revealed a broad peak related to the band-to-band transition of energy at around 1.2 eV and an additional sharp peak positioned at 1.17 eV related to vanadium. Additionally, a non-radiative recombination mechanism followed by hopping through band fluctuation barriers has been proposed for photoluminescence quenching at increased temperatures. The conductivity measurements reveal that conductivity weakly increases with V-doping, whereas its activation energy decreases from around 0.38 eV to 0.35 eV.