Compositionally tunable Cu2Sn(SxSe1−x)3 nanocrystals: facile direct solution-phase synthesis, characterization, and scalable procedure

In this paper, we report a facile, low-cost synthesis of Cu2Sn(SxSe1−x)3 colloidal nanocrystals (NCs) by heating a mixture of metal salts, sulfur powder, selenium powder, oleylamine and dodecanethiol. The composition of the Cu2Sn(SxSe1−x)3 NCs could be tuned across the x range from 0 to 1 by modulating the molar ratio of the S/Se precursors. The lattice parameters (a and c) of the Cu2Sn(SxSe1−x)3 NCs, calculated from X-ray diffraction patterns, were consistent with Vegard's law, confirming the formation of homogeneous nanocrystals. The X-ray diffraction and transmission electron microscopy results indicated that the as-prepared Cu2Sn(SxSe1−x)3 NCs had a monoclinic structure. The UV-visible absorption spectra of the Cu2Sn(SxSe1−x)3 NCs revealed that the band gap of the nanocrystals could be tailored from 1.55 to 1.87 eV by decreasing the Se content. Additionally, compared with the more commonly used hot injection method, the procedure developed here is highly suitable for large-scale colloidal nanocrystal production, which we tested by performing a gram-scale synthesis.