Synthesis of CdSe quantum dots using micro-flow reactor and their optical properties

CdSe quantum dots (QDs) have been synthesized continuously at 200-320°C using a micro-flow reactor. Instead of the usual tri-n-octylphosphineoxide (TOPO)-tri-n-octylphosphine (TOP) solvent, octadecene (ODE)-oleic acid-TOP mixed solvent was used in the present study. Because the ODE-oleic acid-TOP solvent is in liquid form at room temperature, it enabled us to handle the reaction solution at room temperature. The particle size of the QDs synthesized at 250°C was controlled between 3.4 to 4.2 nm by changing the reaction time from 3 to 300s. Clear photoluminescence was observed at 509 nm for 3.4 nm particles and at 578 nm for 4.2 nm particles. In comparison with the QDs synthesized using a small batch reactor, the particle size distribution of the QDs synthesized using the micro-flow reactor was distinctly sharp. The sharp particle distribution came from the accurate controllability of reaction temperature and time due to the short representative length of the micro-flow reactor.