Shell Thickness Modulation in Ultrasmall CdSe/CdS_xSe_1–x/CdS Core/Shell Quantum Dots via 1-Thioglycerol

Abstract

In this study, we report on the synthesis of CdSe/CdS core-shell ultrasmall quantum dots (CS-USQDs) using an aqueous-based wet chemistry protocol. The proposed chemical route uses increasing concentration of 1-thioglycerol to grow the CdS shell on top of the as-precipitated CdSe core in a controllable way. We found that lower concentration of 1-thioglycerol (3 mmol) added into the reaction medium limits the growth of the CdSe core, and higher and increasing concentration (5-11 mmol) of 1-thioglycerol promotes the growth of CdS shell on top of the CdSe core in a very controllable way, with an increase from 0.50 to 1.25 nm in shell thickness. The growth of CS-USQDs of CdSe/CdS was confirmed by using different experimental techniques, such as optical absorption (OA) spectroscopy, fluorescence spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. Data collected from OA were used to obtain the average values of the CdSe core diameter, whereas Raman data were used to assess the average values of the CdSe core diameter and CdS shell thicknesses.

A Versatile Synthetic Approach to Covalent Binding of Polymer Brushes on CdSe/CdS Quantum Dots Surface: Multitype Modification of Nanocrystals

“…CdSe/CdS QDs were grown in aqueous solutions using the approach as reported by Silva et al except that the 1‐thioglycerol was 7.0 mmol.…”

“…Since the first proposal of CdSe QDs synthesis in a simple colloidal route with high quality in 1993, intensive studies have been devoted to the synthesis of high fluorescence CdSe QDs . Typical synthesis protocols needed multiple surface modification to enhance stability . However, surface manipulation has its own drawbacks as it may affect both the physicochemical stability and the optical properties of QDs.…”

“…Surface‐functionalized moieties enhanced the luminescence of CdSe QDs, which reduce surface dangling bonds and defect levels. And core–shell structure also improved the PL intensity and stability of nanocrystals in aqueous medium . However, QDs required structural modification to exploit the applications in devices, which in turn demands the tailoring of the ligands periphery at the surface of quantum dots .…”

A facile route to aqueous Ag:ZnCdS and Ag:ZnCdSeS quantum dots: Pure emission color tunable over entire visible spectrum

“…White-emitting Mn:ZnSe/Cu:ZnS QDs with two emission bands were prepared in an aqueous solution, and the core/shell multilayer structure provided a unique opportunity to dope different types of impurities into each host layer [25]. Currently, a variety of synthetic approaches in the normal atmospheric pressure have been developed to produce QDs, mostly focused on two main methods [26][27][28]. The first one is organic-phase growth, which can produce high-quality QDs with high PL QY [18].…”

Effect of Gd3+ doping and reaction temperature on structural and optical properties of CdS nanoparticles

“…In the recent years, a number of papers have been published on synthesis and applications of CdS and trivalent rare-earth ions doped CdS NPs [16][17][18][19][20][21][22][23][24]. However, the few recent reports on Gd:CdS, prepared in organic phase [25], and in aqueous phase [26], have shown poor control on size and shape of NCs.…”