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

CdSe quantum dots (QDs) have been synthesized continuously at 200-320degreesC using a micro-flow reactor. Instead of the usual tri-n-octylphosphincoxide (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 250degreesC was controlled between 3.4, to 4.2 nm by changing the reaction time from 3 to 300 s. 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 particles 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.