A robust strategy for "living" growth of lead sulfide quantum dots

Abstract

Colloidal quantum dot (QD) nanocrystals of lead sulfide (PbS) have promising applications in diverse scientific fields due to their size-tuned band gaps, but the batch synthesis of differently sized QDs is cumbersome. In this paper, we report a robust method to synthesize monodisperse PbS QDs through a novel “living” growth process, in which a series of differently sized QDs can be easily produced upon step-wise heating the preformed seed QDs in the presence of excessive PbS monomers, that is, un-crystallized PbS. The mechanism for such a QD growth is associated with the combination of “living” monomer addition to existing QDs to increase particle sizes and Ostwald ripening to focus particles. The outcome is not only able to produce various high-quality QDs without extensive synthetic work, but also provide new insight into the mechanism of synthesizing semiconducting colloidal nanocrystals.