Template synthesis of silver indium sulfide based nanocrystals performed through cation exchange in organic and aqueous media

Heavy-metal-free silver based I-III-VI semiconductor nanocrystals (NCs), including ternary silver indium sulfide (AgInS 2 ) and derivative quaternary silver indium zinc sulfide (i.e., AgInZn 2 S 4 ) NCs, possess advantages of low toxicity, and size-tunable band gaps approaching near-infrared spectral range, which make them candidates for use in optoelectronic and biological devices. Herein, we report syntheses of AgInS 2 based NCs starting from In 2 S 3 template, which have been performed both in organic and aqueous phase through cation exchange. As a result, ternary silver indium sulfide and quaternary silver indium zinc sulfide NCs are obtained in both organic and aqueous media, and confirmed to be orthorhombic AgInS 2 NCs and hexagonal AgInZn 2 S 4 NCs, respectively. Furthermore, the aqueous AgInZn 2 S 4 NCs with red emission and low cytotoxicity are explored for the cancer cell imaging.