Preparation And Properties Of CuInS₂ Core Shell Structure Quantum Dots

Fluorescent quantum dots is a size between 1-10 nm nanoparticles. When the size is less than the Bohr radius, showing obvious quantum confinement effect. The electrons and holes at the limited domain, continuous band with molecular properties become discrete band structure, and fluorescent quantum dots will produce fluorescence by inspired. Fluorescent semiconductor quantum dots have been attracted widespread attention because of their special optical properties especially in the fields of solar cells, light-emitting devices and biological labeling etc. In this paper, based on the widely used of fluorescent semiconductor quantum dots, yellow-green (CuInS2/ZnS), red-orange (CuInS2/CdS) fluorescent quantum dots have been synthesized, the formation and luminescence mechanism of fluorescent semiconductor quantum dots have been studied. In addition, independent design and assembly of semi-continuous fluorescent quantum dot production plant to meet the growing needs of fluorescent quantum dots. Details are as follows:1)CuInS2 quantum dots and CuInS2/ZnS core-shell quantum dots have been synthesized using one-pot method, studying the impact of reaction time, temperature, Cu/In to quantum dot structure and luminescence properties. CuInS2 quantum dot fluorescence emission peak appears in the range of 620 nm-670 nm, TEM images show the quantum dot size distribution and the average size of CuInS2 quantum dot is 2-3 nm. The obtained CuInS2 quantum dots are chalcopyrite phase structure by XRD and Raman characterization. CuInS2 quantum dots are synthesized by simple surface passivation of zinc stearate processing, XRD and Raman characterization have also proved ZnS shell formed on the surface, forming CuInS2/ZnS core-shell quantum dots, fluorescent emission peak appears from 520 nm-620 nm, fluorescence quantum yield is greatly increased to 75%.2) Using the one-pot method for synthesizing CuInS2 core quantum dots, CuInS2/CdS core-shell quantum dots are synthesized via heat-injection method and discussing different Cu/In, Cd/S, reaction time to impact the quantum dot structure and luminescence properties. CuInS2/CdS core-shell quantum dots are synthesized by surface passivation of CdS cadmium oleate and sulfur powder as cadmium precursor and sulfur precursor. CdS shell layer is formed on the CuInS2 surface, which proved by XRD and Raman characterization, fluorescence emission peak appears in the range of 620 nm-670 nm, and the fluorescence quantum yield is 89%.3) Semi-continuous production of fluorescent quantum dots device is independent designed and built, which contains a feed tank, mixing tank, oil bath, spiral reaction tubes, electric mixer, peristaltic pump, display panel and other components. CuInS2 quantum dots and CuInS2/ZnS core-shell quantum dots are synthesized using this device, CuInS2 quantum dot fluorescence emission peak appears in the range of 625 nm-670 nm. CuInS2/ZnS core-shell quantum dot fluorescence emission peak appears in the range of 550 nm-570 nm, the fluorescence quantum yield is 50%.