Synthesis of high quality and stability CdS quantum dots with overlapped nucleation-growth process in large scale

A low-cost, green, and reproducibly non-injection one-pot synthesis of high-quality CdS quantum dots (QDs) is reported. The synthesis was performed in the open air by mixing precursors cadmium stearate and S powder into a new solvent N-oleoylmorpholine. An overlapped nucleation-growth stage followed by a dominated growth stage was observed. The resulting QDs exhibited well-resolved absorption fine substructure and a dominant band-edge emission with a narrow size distribution (the full width at half maximum (fwhm) was only 22–24 nm). The maximum photoluminescence (PL) quantum yield (QY) was as high as 46.5%. Highly monodispersed CdS QDs with tunable sizes and similar PL fwhm and QYs could also be obtained from the CdS QDs in a large-scale synthesis. The high-resolution transmission electron microscopy (HRTEM) images and powder X-ray diffraction (XRD) pattern suggested that the as-prepared QDs with high crystallinity had a cubic structure. A significant PL improvement and a continuous QY increase for the CdS QDs were observed during a long storage time in air and in a glovebox under room temperature. A slow surface reconstruction was proposed to be the cause for the PL enhancement of CdS QDs.

With no aid of any nucleation initiators, a low-cost, green, and reproducibly one-pot approach was reported for the highly monodispersed CdS QDs with a narrow size distribution and excellent optical properties.Figure optionsDownload high-quality image (71 K)Download as PowerPoint slideResearch highlights
► A one-pot approach was developed for the synthesis of high-quality CdS QDs at the absence of any nucleation initiators.
► A new, air-stable, and low-cost benign solvent of N-oleoylmorpholine was used.
► An overlapped nucleation-growth mechanism was proposed.
► The long-term continuous PL enhancement and QY increase were observed.