A Colloidal Synthesis Route Towards AgBiS₂ Nanocrystals Based on Metal Xanthate Precursors

Silver bismuth sulfide (AgBiS₂) is showing impressive thermoelectric and photovoltaic properties and has a high potential to replace toxic cadmium or lead containing semiconductors in many applications. Herein, we report on a synthesis route for AgBiS₂ nanocrystals applying metal xanthates as precursors. Silver xanthates could not be used so far in solution-based syntheses for Ag-containing metal sulfide nanocrystals as they are typically insoluble in organic solvents. An investigation of the synthesis process revealed that even though the silver xanthate is not soluble in the used solvent mixture consisting of octadecene and oleylamine, the decomposition of both precursors and the formation of AgBiS₂ nanocrystals is initiated already at room temperature by the amine functionality of the ligand. At room temperature, primary crystallite sizes of approximately 4 nm are observed and at a reaction temperature of 200 °C, the size of the AgBiS₂ nanocrystals increases to 7–8 nm.