A facile synthetic route toward phase-pure colloidal Cu2GeS3 nanostructures mediated through metal xanthate precursors

Abstract

Copper germanium sulfides (CGSs), a class of ternary I–IV–VI semiconductor metal chalcogenides, are considered quite desirable when it comes to efficient light harvesting materials for cost-effective and sustainable solar cells. Producing phase-pure CGS materials, free from binary impurities at the nanoscale is highly desirable. This report outlines a simple and easily scalable pathway toward phase-pure cubic Cu₂GeS₃ nanostructures via the thermolysis of copper and germanium isopropylxanthates in oleylamine (OAm). The crystal structure, phase purity, morphology, elemental composition and band gap of the as-synthesized Cu₂GeS₃ nanostructures were thoroughly evaluated via powder X-ray diffraction (PXRD), Raman spectroscopy, scanning and transmission electron microscopy (SEM and TEM), energy dispersive X-ray spectroscopy (EDS), and UV-Vis and diffuse reflectance spectroscopy (DRS), respectively. The band gap of these nanomaterials lies in an optimum range for solar cell applications. Finally, the pristine Cu₂GeS₃ nanocrystal-based prototype photoelectrochemical cells exhibit photovoltaic activity along with high photoresponsivity and stability under alternating light and dark conditions, which make them promising candidates for alternative low-cost photon absorber materials.