Simplistic toxic to non-toxic hydrothermal route to synthesize Cu₂ZnSnS₄ nanoparticles for solar cell applications

Solution-synthesized nanostructured Cu₂ZnSnS₄ (CZTS) has attracted significant attention as a promising candidate for use as an efficient and inexpensive photovoltaic energy convertor material. In general, the solution synthesized route involves the use of toxic and explosive chemicals. The current report emphasizes a non-toxic surfactant mediated hydrothermal route for the synthesis of CZTS NPs (CZTS NPs) without the use of toxic chemicals. The physical and chemical properties of the CZTS NPs were studied using X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) techniques. The XRD and Raman spectroscopy results confirmed the formation of single-phase kesterite CZTS NPs. TEM analysis revealed the formation of well-dispersed CZTS NPs that were ~5-10nm in size. The sodium dodecyl sulfate surfactant played a key role in the formation of the CZTS NPs. The optical absorption studies revealed that the CZTS NPs had an optical band gap of 1.85eV, which is favorable for photovoltaic applications. The synthesized CZTS NPs could be used in the form of ink, which could be used to directly coat large area thin film solar cells. Moreover, the probable reaction mechanism for the formation of surfactant assisted CZTS NPs is proposed in present report.