Hot-injection synthesis of highly luminescent and monodisperse CdS nanocrystals using thioacetamide and cadmium source with proper reactivity

Thioacetamide (TAA) has served as an excellent sulfur source to react with cadmium stearate to controllably produce highly luminescent and monodisperse CdS nanocrystals through the hot-injection method in dodecylamine solvent. The kinetics and thermodynamics of nucleation/growth of CdS nanocrystals, as well as their optical properties are controlled by changing synthesis conditions such as reaction time, injection/growth temperatures, TAA concentration and cadmium source with different reactivity. Temperature-dependent release of reactive sulfur species from TAA, together with proper reactivity of cadmium source, facilitates the better separation of nucleation and growth stage, the formation of highly monodisperse CdS nanocrystals with tunable size and further self-assembly into ordered superlattices. When cadmium carboxylates such as cadmium stearate and cadmium oleate are used as cadmium sources, surface trap emission of CdS nanocrystals can be gradually removed to obtain bright pure-blue emission with increasing reaction time. The highest quantum efficiency of up to 33.6% is achieved when using cadmium stearate as cadmium source at the injection/growth temperatures of 230/210 °C for 90 min.

Graphical abstractHighly luminescent and monodisperse CdS nanocrystals were controllably synthesized using thioacetamide and relatively inactive cadmium source in dodecylamine solvent; bright blue emissions were achieved by adjusting reaction time.Figure optionsDownload full-size imageDownload high-quality image (143 K)Download as PowerPoint slide