Synthesis of band-gap tunable Cu–In–S ternary nanocrystals in aqueous solution

Cu–In–S ternary nanocrystals (NCs), with an average size of less than 10 nm, were synthesized in an aqueous solution containing bovine serum albumin (BSA). X-Ray powder diffraction (XRD) and selected-area electron diffraction (SAED) analyses showed that these NCs featured a roquesite structure. The composition of the NCs could be adjusted by controlling the molar ratio of the starting Cu/In precursors in the reaction solution, which led to a tunable band gap ranging from 1.48 eV to 2.30 eV. Cytotoxicity testing showed that the BSA-stabilized Cu–In–S NCs had little effect on the cell viability, which suggested that they are user-friendly and environmentally benign. With low cost, minimal energy input and environmental impact, this simple approach shows great potential for industrial applications.