Controllable synthesis and growth mechanism of dual size distributed PbSe quantum dots

Abstract

To understand the fundamental science of nanocrystal growth, the controllable synthesis and growth mechanism of dual size distributed PbSe quantum dots (QDs) are studied. The characterizations of high-resolution transmission electron microscopy (HR-TEM) and photoluminescence (PL) unambiguously demonstrate the dual size distribution of PbSe QDs. Thermodynamic stability of small QDs is confirmed by a controllable synthesis of temperature variation and kinetic perturbation with successive injection of precursors, suggesting a possible mechanism that a chemical-potential well may lead to the size separation. The control of growth temperature plays an important role in the realization of dual size distributed PbSe QDs. Further study of temporal evolution demonstrates the size refocusing of QDs at a higher temperature. Both kinetic perturbation and thermodynamic perturbation could facilitate QDs to overcome the potential barrier. Understanding this mechanism is of significance for the controllable synthesis and applications of PbSe QDs.