Efficient and scalable synthesis of quantum dots using hexane as the solvent in a non-microfluidic flow reactor system

Abstract

Quantum dots (QDs) synthesis has been widely carried out in Schlenk line systems. However, there are two drawbacks of these systems, which have restricted their use for large scale or commercial production of QDs. One is the use of expensive and high-boiling point solvents and the other is that QDs need to be continuously produced with high production rate to reduce production costs. Nowadays, microfluidic flow systems are the most popularly used systems for the continuous production of QDs. However, their narrow channels limit the reaction volume and flow rate. In this report, a non-microfluidic flow reactor system has been developed to synthesize high quality CdSe QDs by injecting the solution containing the mixture of Cd–oleic acid (Cd–OA) and Se–tributylphosphine (Se–TBP) into near critical or supercritical hexane. The optical properties of the produced CdSe QDs can be fine-tuned to almost cover the entire visible region (450–630 nm) by changing the reaction parameters. The CdSe QDs produced with this approach are similar to those produced in Schlenk line, and can be functionalized with a ZnS shell to enhance PL efficiency. Moreover, we have also achieved a continuous synthesis of 5 g CdSe QDs with a production rate of 2.5 g h⁻¹ to demonstrate the potential capability of mass production with this system. White light emitting diodes can be prepared by using CdSe QDs as the phosphor dye. Finally, other types of QDs, such as CdS, ZnS, and ZnSe, were also synthesized to demonstrate the generalization of the developed approach.