Open-to-air synthesis of monodisperse CdSe nanocrystals via microfluidic reaction and its kinetics

Abstract

Monodisperse zinc blende CdSe nanocrystals (NCs) ranged from 2.5 to 4.3 nm have been reproducibly synthesized directly open to air in a microfluidic reactor with PTFE capillaries acting as the reaction channels. The foregoing features led to superior operational stability, allowing the assessment of kinetic data such as temperature, dwelling time and ligand concentration. Red shifts of the absorption spectra were observed with increasing residence time and temperature. `Crossover time' of size distribution was first reported in a microfluidic reactor preceded by encouraged Ostwald ripening at high reaction temperature. Oleic acid concentration influenced the formation of CdSe NCs, and high OA to Cd ratio resulted in large NCs size and decreased CdSe concentration. By systematic optimization of the parameters, CdSe NCs with FWHM for the photoluminescence peak in the range from 35 to 42 nm were thus made possible.