Soluble Complexes Destruct Metal-Alkanoate Clusters in the Mixture of Colloidal Quantum Dots

Abstract

Metal alkanoates represent the most challenging impurities in quantum dot (QD) purification. These species readily form clusters through extended metal–carboxylate coordination in common QD solvents. When present in QD dispersions, such clusters coassemble with QDs to generate insoluble and gel-like aggregates. Herein, we demonstrate that these clusters and related assemblies can be effectively disassembled via the introduction of tetramethylammonium alkanoate (NMe4Al). This strategy enables facile purification of diverse QDs through selective precipitation of the QDs within a single toluene–acetonitrile dissolution–precipitation cycle. The generalized complex-based purification protocol fully preserves the native surface ligands of QDs, thereby retaining their photoluminescence quantum yields and colloidal stability. This generalized purification protocol is expected to play a key role in fundamental research and technical applications of colloidal QDs.