Optical Properties of ZnS Quantum Dots: Applications in Solar cells and Biomedicine

Abstract

Optoelectronics and optical filter applications require wide bandgap semiconductors as photo-anode and surface passivation layers in sensitized solar cells and biomedical and biosensors fields such as optical filters [1–4]. Selecting suitable wide bandgap semiconductors increases the valuable implementation of desired devices. However, bulk semiconductors harvest only a particular spectrum, QDs help in harvesting large radiation spectra because of the tunable bandgap. Also, aqueous-based methods are eco-friendly, economical, biocompatible, and non-toxic. Therefore, in this study, ZnS quantum dots (QDs) were synthesized at 9.5 pH and 70 ͦ C temperature using an aqueous-based chemical route method. A comparative study was presented using hydrazine hydrate and ammonium chloride as reducing agents for Zinc precursor and 3-mercaptopropionic acid (MPA) as capping agents. Confinement was achieved in ZnS using MPA as a stabilizer. Optical properties were studied using a photoluminescence (PL) spectrophotometer where photoluminescence (PL) shows emission behavior and photoluminescence excitation (PLE) shows excitation behavior of ZnS. Emission peaks were observed at 386 nm in as-prepared ZnS NPs and at 316 nm in confined QDs. Sharp band edge luminescence and the possibility to confine ZnS NPs show its eligibility in optoelectronics and optical filters in biological applications.