Synthesis and characterization of (Cu1−xAgx)2ZnSnS4 nanoparticles with phase transition and bandgap tuning

Multi-component chalcogenide (Cu 1− x Ag x ) 2 ZnSnS 4 (CAZTS, x  = 0, 0.1, 0.2, 0.3, 0.4) nanoparticles were synthesized by incorporation of Ag into wurtzite Cu 2 ZnSnS 4 (CZTS) using a simple one-pot method and were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and UV–Vis–NIR absorption spectrum, respectively. The synthesized nanoparticles exhibit the phase transition from wurtzite to kesterite structure when the substitution ratio ( x ) of Ag is around 0.3. The bandgaps of CAZTS nanoparticles are in the range of 1.43–1.64 eV. This finding indicates that Ag substitution in wurtzite CZTS is an effective way to adjust the bandgap and structure.