Preparation and characterization of Cu2FeSnS4 quaternary semiconductor thin films via the spray pyrolysis technique for photovoltaic applications

- P-type Cu2FeSnS4 absorber layers were synthesized by a simple chemical spray pyrolysis technique.
- Data analysis revealed pure stannite structure along with nearly stoichiometric in films.
- High absorption coefficient values close to 105 cm−1 and optimum band gap about 1.50 eV was found.
- Hall effect data including hole density and their mobilities are presented.

The Cu2FeSnS4 (CFTS) nanostructured thin films have been spray deposited onto glass substrates without any post-sulfurization in toxic atmosphere such as H2S or 'S' vapor. The influence of substrate temperatures on the structural, morphological, compositional, optical, electrical and photoconductivity properties of the CFTS thin films have been studied. These properties are found to be strongly dependent on the substrate temperature. XRD spectra analysis revealed that all CFTS thin films showing pure stannite structure. The improved crystallinity of the CFTS with a (112) orientation was observed with increasing the substrate temperature. The spray synthesized CFTS films exhibit a smooth, uniform and dense topography. EDS study reveals that the deposited thin films are nearly stoichiometric. The direct band gap energy for the CFTS thin films is found to be about 1.50 eV, which is close to the ideal band gap for the highest theoretical conversion efficiency of solar cell. Electrical conductivity and hole mobility of the CFTS films increases with increasing substrate temperatures. The films were p-type and shows photoconductivity. Electrical measurements (I-V curves) were registered in dark and under light exposure and were correlated with the films composition and structure, as obtained from the EDS analysis and XRD patterns.