Effect of sulfurization temperature on properties of Cu₂SnS₃ thin films and solar cells prepared by sulfurization of stacked metallic precursors

Cu₂SnS₃ (CTS) thin films were synthesized by the sulfurization of stacked metallic precursor fabricated with a radio frequency magnetron sputtering method. The compositional, structural, morphological, optical and electrical properties of CTS thin films grown on soda lime glass substrates depend on the sulfurization temperature. The compositional analysis shows that all samples are in Sn-rich state. The ratio of Cu/Sn is close to the stoichiometric composition of CTS with increasing sulfurization temperature. The CTS thin films sulfurized at higher sulfurization temperature have better crystalline quality from the results of structural characterization. The CTS thin film obtained at sulfurization temperature 550 °C exhibits higher degree of crystallization with larger average grain size. The transmission and reflectance spectra demonstrate the band gap is around 1.0 eV, which is consistent with the estimation extrapolated from external quantum efficiency. The photoelectric properties of solar cell are enhanced with the increase of sulfurization temperature. The solar cell fabricated with the CTS absorber layer annealed at 550 °C has the efficiency up to 0.28% for a 0.16 cm² area.