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.