Synthesis of CZTSe Nanocrystal Prepared by a Facile Route in Coordinating Solvent From Elemental Sources

This paper reports the preparation of Cu₂ ZnSnSe₄ (CZTSe) nanocrystals from elemental sources through the application of various coordinating solvents. The CZTSe nanocrystals were synthesized by mixing metals in oleylamine (OLA) and isophorondiamine (IPDA) at a ratio of 1:3 as well as a Se solution in trioctylphosphine (TOP) under N₂ flow at atmospheric pressure at a reaction temperature of 235 °C. X-ray diffraction and Raman spectroscopy were used to track the reaction mechanisms associated with various solvents. A growth mechanism, distinct from that associated with TOP/OLA, promoted the formation of nanoparticles and improved the reactivity provided by the addition of IPDA solvent through double N-chelation. The reaction mechanism involved in stannite Cu₂ ZnSnSe₄ phase crystallization from Cu₂ SnSe₃ and ZnSe is supported by theoretical analysis. The monodispersed CZTSe nanocrystals are polycrystalline and 20-30 nm in size. Optical measurements revealed a direct band gap of 1.42 eV. This study presents a relatively simple, low cost coordinating solvent route for the synthesis of CZTSe nanoparticles, applicable to the fabrication of low-cost thin-film solar cells.