The formation mechanism of CdSe QDs through the thermolysis of Cd(oleate)2 and TOPSe in the presence of alkylamine

Abstract

The thermal decomposition of Cd(oleate)₂, a metal organocarboxylate complex, in the presence of alkylamine was studied in order to understand the formation mechanism of CdSe nanocrystals (quantum dots, QDs) in the hot-injection method. The major intermediates and side products were characterized by nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The results showed that the nucleophilic attack of the metal-coordinated amine toward the most electron-deficient carbonyl carbon of the oleate ligands initiated decomposition to generate a CdO cluster (or oligomer). Based on our experimental results, we proposed a two-step formation mechanism of CdSe QDs involving the formation of CdO intermediates with alkylamines playing a critical role as nucleophiles in the thermolysis process, followed by a metathesis reaction with trioctylphosphine selenide (TOPSe) as a chalcogenide source.