Synthesis, characterization and stability study of aqueous MPA capped CuInS2/ZnS core/shell nanoparticles

Abstract

Ternary I–III–VI nanoparticles (NPs) emerged as potential alternatives to II-VI group NPs. At present, it remains a tremendous challenge to directly synthesize high-quality CuInS2/ZnS (CIS/ZnS) core/shell NPs in aqueous solution at atmospheric pressure. Herein, a simple and reliable strategy that combines the hydrothermal method and successive ion layer adsorption and reaction has been proposed to realize the aqueous synthesis of fluorescent CIS/ZnS core/shell NPs. XRD depicts the formation of tetragonal chalcopyrite structure of CIS quantum dots (QDs). As synthesized CIS QDs and CIS/ZnS NPs possess spherical symmetry with average diameter of 6.6 nm and 11.2 nm, respectively. FT-IR spectra confirms the capping of MPA on CIS and CIS/ZnS NPs. UV–Vis spectra of core QDs and core/shell NPs does not show any direct absorption peak. After the growth of ZnS shell over CIS QDs, the PL QY of NPs reach from 6.95% to 17.19%. The stability and behavior of core and core/shell NPs in different pH, has been studied from both absorption and PL observations. Maximum PL emission intensity is found at pH 6 for both core and core/shell NPs. PL QY of core/shell NPs reduces from 17.19% to 8.08% after two months of storage. These properties make them promising candidates for biological and optoelectronic applications.