Effect of the spraying temperatures and the sulfurization on the properties of the absorber Cu2FeSnS4 thin films in a solar cell

•We have deposited CFTS thin films by spray technique on glass substrates.•These films exhibits a stannite structure, Eg of about 1.5 eV and α equal to 105 cm−1.•The thickness of the films is around 0.8 μm. The quaternary Cu2FeSnS4 (CFTS) is regarded like the one of the semiconductors promoting as an effective photovoltaic absorber because of their earth-abundant and non-toxic elements. The thin films were elaborated by spray pyrolysis method deposited onto glass substrates at 370 °C for one hour with post-sulfurization treatment at 450 °C for 30 min. XRD spectra analysis showed that the CFTS thin films have tetragonal structure with a main peak corresponding to the direction (1 1 2). The Raman spectrum confirmed these results with an appearance of two main peaks corresponding to the CFTS situated at the positions 289 cm−1 and 318 cm−1. The CFTS films exhibit a homogeneous, rough and dense topography with a thickness of about 0.8 μm. The films of CFTS present a high absorption coefficient (≥105 cm−1) and the direct band gap energy is found to be 1.55 eV, which confirms their use as an absorber for solar cells.