Synthesis of ZnSe Quantum Dots Using a Continuous-Flow Microreactor and Their White Emission through Energy Transfer

Abstract

Materials and Method Zinc acetate (99.99%), selenium (100 mesh, 99.999%), 1-octadecene (ODE, 95%), oleylamine (OLA, technical grade), and octadecylamine(ODA,technicalgrade)werepurchasedfromAldrich. Tributylphosphine (TBP, technical grade) was purchased from TCI. The Zn precursor solution was prepared by heating Zn acetate (0.07 g, 0.4 mmoL) with OLA (0.4 mL, 1.2 mmoL) around 170 ◦ C until the solutionturnedclear.FortheSeprecursorsolution,Sepowder(0.05g, 0.6 mmoL) was dissolved in 1.0 mL of TBP to form the transparent solution and then ODA powder (0.05 g, 0.2 mmoL) was dissolved in that mixture, and finally 1.0 mL of ODE was added. Finally, the solutions of the Zn and the Se precursors were mixed with each other by stirring, and they were delivered in a microcapillary using a syringe pump. The flow rate was changed from 5 to 25 μLmin −1 .T he polytetrafluorethylene (PTFE) microcapillary with 500 μm inner diameter was connected from the syringe to an outlet via the reaction part. The reaction part was heated by an oil-bath at 200‐240 ◦ C, and the length of the heating zone in the microtube was around 20 cm. The prepared ZnSe QDs were collected and dispersed in hexane or chloroform, and they were purified by precipitation with addition of methanol and acetone.