Influences of synthesis conditions on chemical composition of Cu₂ZnSnS₄ nanocrystals prepared by one pot route

In present work, the Cu₂ZnSnS₄ (CZTS) nanocrystals (NCs) were successfully synthesized via a rapid and simple one pot route. The influences of the reaction temperature and time on the chemical composition were first investigated in detail by energy dispersive X-ray spectroscopy. Meanwhile, the variations of the structural, morphological and optical properties of the as-synthesized CZTS NCs were analyzed by combining with the changes of the chemical composition via x-ray diffraction, field emission scanning electron microscopy (FE-SEM) and UV–Vis–IR spectrophotometer, respectively. It was found that the reaction temperature and time had significant impacts on the element composition, especially for the variations of Zn and Sn; and the variations of structure, morphology and band gap energy were closely linked with the changes of Zn and Sn. The characterization results of the as-synthesized CZTS NCs, under the optimal synthesis condition (250 °C, 1 h), were shown as following: the compositional ration was near stoichiometric (Zn/Sn = 0.81, Cu/(Zn + Sn) = 0.97, S/(Cu + Zn + Sn) = 1.07), the average size of NCs was 19.98 nm, the size of aggregation nanoparticles was in the range of 200–500 nm, and the band gap energy was 1.5 eV. All results suggested that the as-synthesized CZTS NCs were good light absorption layer material for thin film solar cell.