Improvement of monodispersity of PbS quantum dots by filtration with organic solvent-resistant polyamide hollow fiber membranes

Abstract

We report that membrane filtration can replace centrifugation as a highly efficient size classification process of colloidal quantum dots (QDs) after chemical synthesis. The production of colloidal QDs requires the separation of the targeted QDs dispersed in organic solvents from other by-products. The separation process has been conventionally performed by centrifugation. We investigated replacing the centrifugation with filtration using organic solvent-resistant polyamide hollow fiber membranes (HFMs). By choosing the pore size of HFMs, QDs of arbitrary size were classified. It was also demonstrated that not only large QDs but also small QDs could be separated simultaneously by using HFM with a dense layer of polyamide inside. Consequently, highly monodisperse QDs were easily obtained in a single filtration operation using HFMs.