Cu2ZnSnS4crystal growth using an SnCl2based flux

Abstract

The stoichiometry and phase homogeneity of the kesterite type compound Cu2ZnSnS4play a key role in its efficiency in solar cells. In this work, CuCl2, ZnCl2and SnCl2were applied as solvents in the Cu2ZnSnS4crystal growth for the first time. The multiphase ingot was obtained by direct fusion of the stoichiometric batch composed of constituent elements. Compared to that, the material recrystallized in SnCl2presented a single-phase Zn-rich kesterite with composition Cu1.94Zn1.06SnS4and unit cell parameters ofa= 5.4324(3) andc= 10.8383(2) Å. The crystal structure of Cu1.94Zn1.06SnS4was determined by single crystal X-ray diffraction analysis. The integral phase purity of the crystals grown with the use of the SnCl2solvent was verified by powder X-ray diffraction analysis and Raman measurements. In the Raman spectrum, the FWHM value of the 337 cm−1line was as low as 9.6 cm−1that indicates the minimal lattice disorder. © The Royal Society of Chemistry 2021.