Solution-based synthesis and characterization of Cu2FeSnS4 nanocrystals

Cu2FeSnS4 nanocrystals were cost-effectively synthesized by thermal reactions of metal salts and sulfur in a hot oleylamine solution. Stannite structured Cu2FeSnS4 nanocrystals with diameters of about 15–25 nm were obtained, analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The morphology of the continuous Cu2FeSnS4 thin films was characterized by scanning electron microscopy (SEM) and the average compositions of the nanocrystals were determined by energy dispersive X-ray analysis (EDX). High-resolution X-ray photoemission spectroscopy (XPS) analysis of the four constituent elements indicated Cu (I), Fe (II), Sn (IV) and sulfide ions. The band gap of as-synthesised Cu2FeSnS4 nanocrystals is about 1.33 eV determined by the UV–vis–NIR absorption spectra measurement, which indicates its possible solar cell applications.