A facile and low cost synthesis of earth abundant element Cu2ZnSnS4 (CZTS) nanocrystals: Effect of Cu concentrations

Cu2ZnSnS4 (CZTS) nanocrystals (NCs) were synthesized by sulfurization of microwave assisted precursor powders without toxic chemicals. The effects of different Cu concentration from 0.01 to 0.025 M on the structural, morphological, compositional, chemical and optical properties of CZTS NCs were investigated. X-ray diffraction patterns, X-ray photoelectron spectroscopy and transmission electron microscopy results showed that the precursor powder contains several broad peaks that could not be assigned to CZTS, ZnS, Cu2-xS, Sn2S3 and Cu2SnS3. However, the sulfurized NCs showed both kesterite CZTS and Cu- and Sn-based secondary phases except for that formed at Cu concentration of 0.02 M. Inductively coupled plasma (ICP) results showed that the presence of Cu in the sulfurized CZTS NCs increased with increasing Cu concentration from 16.57 to 32.94 at.% while Zn and Sn in the sulfurized CZTS NCs decreased with increasing Cu concentration. UV–Vis spectroscopy results showed that the absorption coefficient of the sulfurized NCs was over 104 cm−1 in the visible region and band gap energy of the sulfurized CZTS NCs decreased from 1.65 to 1.28 eV with increasing Cu concentration.

► Cu2ZnSnS4 (CZTS) nanocrystals (NCs) were prepared by sulfurization of microwave assisted precursor without toxic chemicals.
► Effect of Cu concentration on the properties of CZTS NCs was investigated using various analysis methods.
► The properties of CZTS NCs was strongly related to the Cu concentrations.