Raman Spectroscopy as a Superior Tool To Understand the Synthetic Pathway of Cu 2 FeSnS 4 Nanoparticles

The quaternary chalcogenide Cu 2 FeSnS 4 is important and interesting owing to its many advantageous characteristics for photovoltaic and optoelectronic applications, such as a suitable direct band gap (1.0–1.5 eV), low toxicity, and a relatively high abundance of the elements in the Earth's crust. To date, most of the reports on Cu 2 FeSnS 4 have focused on the synthetic method and optical properties, and few studies have comprehensively and systematically reported the growth mechanism of Cu 2 FeSnS 4 nanoparticles. Therefore, we have synthesized Cu 2 FeSnS 4 nanocrystals by a simple hot‐injection method and performed detailed characterizations. Raman spectroscopy is a characterization tool to differentiate the mixed‐composition phases in the synthetic pathway of Cu 2 FeSnS 4 nanocrystals, which cannot be efficiently distinguished by X‐ray diffraction. A possible synthesis mechanism for Cu 2 FeSnS 4 has been proposed.