Supercritical Continuous-Microflow Synthesis of Narrow Size Distribution Quantum Dots

Abstract

The continuous microflow synthesis of CdSe quantum dots (QD) at high pressure both in a conventional high-boiling-point solvent, squalane, and also in liquid hexane, was demonstrated. All experiments were performed in Silicon/Pyrex microreactors that allow for easy optical access and sustain high pressures. Synthesis of CdSe QDs was carried out at 5 MPa. The residence time was tuned from 30 to 150s by varying the flow rate. Typical photoluminescence spectra as a function of residence time for CdSe QDs synthesized in liquid squalane and sc-hexane at 270°C and 5 MPa with a precursor concentration of 3.8×10-3 M, was obtained from TEM measurements. The average QD diameter was determined using the wavelength at the emission maximum. Comparison between solvents shows that at a given residence time, QDs synthesized in sc-hexane are approximately 20-30% smaller than those synthesized in liquid squalane.