Synthesis of CZTS Nanocrystals and Transformation into CZTSe

In this work, we present an alternative route to synthesize Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) nanocrystals in controlled proportions. Initially, CZTS nanocrystals are formed through a hot-injection method with oleylamine as the solvent. Thereafter, selenium dissolved in TOP (trioctylphosphine) is injected and a transformation from CZTS to CZTSe is observed to occur. Here we present a demonstration that the transformation is possible, a first view on how the morphology of the nanoparticles changes, and our results from optimizing the conversion ratio with respect to temperature. Our X-ray diffraction pattern proves that liquid conversion from CZTS to CZTSe is possible, and from transmission electron micrographs we see that the CZTSe particles are significantly larger than the CZTS nanoparticles prepared under equivalent conditions. Finally, we find that increasing the temperature results in a larger amount of conversion from CZTS to CZTSe after a fixed amount of time.