Polyvinylpyrrolidone as a polymer template for CuInS quantum dots: Effect on optical properties

Ternary I–III–VI quantum dots (QDs) are promising candidates for biomedical and bio-imagining applications. This is a result of the presence of less toxic elements compared to traditional QDs. Polymers are biocompatible, biodegradable, and nonimmunogenic, making them exceptionally suitable for in vivo therapeutic applications. Coating QDs with polymers has been reported to improve QDs stability, reduce toxicity, and introduce chemical functionalities on the surface of the QDs. Polyvinylpyrrolidone (PVP) is an amorphous water-soluble and non-toxic polymer commonly used in the pharmaceutical and biomedical industry as a vehicle for dispersing and suspending drugs. In this study, CuInS QDs was synthesized hydrothermally using as dual stabilizers (i.e. glutathione and sodium citrate). The optical properties of the QDs proved to be composition and pH-dependent as an increase in intensity and tuneability of the emission peaks was obtained with varying synthesis parameters. To eliminate the shoulder peak due to the surface defect in the CuInS QDs and improve the optical properties of the bare QDs, the CuInS QDs was coated with PVP. For optimum synthesis conditions, pre-synthesis exposure of the QDs to varying amounts of the polymer was investigated. The generated (PVP) CuInS QDs yielded different behaviour in terms of stability, optical properties (UV and PL), and surface coating compared to the core CuInS QDs. The distinctive photophysical properties of the (PVP) CuInS QDs paves the development of quality polymer coated CuInS QDs for bio-imaging application.