A reactivity-controlled epitaxial growth strategy for synthesizing large nanocrystals

Abstract

Large ZnSe nanocrystals are expected to be promising blue-light emitters with an emission peak of 455–475 nm, which is important for the construction of display apparatus. The final size of ZnSe nanocrystals via one-step injection can be varied by the reactivity of the Zn and Se precursors; however, it has a limit of <5 nm. To describe the key factors in determining the final size of ZnSe nanocrystals, we proposed a nuclei number-considered LaMer model based on the Maxwell–Boltzmann distribution of crystal embryos. As a result, a general strategy of reactivity-controlled epitaxial growth was developed to synthesize large ZnSe nanocrystals through sequential injection of high-reactivity and low-reactivity Zn and Se precursors. The resultant ZnSe nanocrystals achieved pure blue emission between 455 and 470 nm. We further fabricated stable, large ZnSe/ZnS core–shell nanocrystals with photoluminescence quantum yields up to approximately 60%. Moreover, the reactivity-controlled epitaxial growth strategy is versatile and could be used to synthesize large ZnSe, CdSe and PbSe nanocrystals with average sizes up to 35 nm, 76 nm and 87 nm, respectively. The control of quantum-confined and classical effects in these large semiconductor nanocrystals will open up new directions for fundamental research and application exploration. Synthesizing Se-based nanocrystals with large diameters remains challenging. Here, a reactivity-controlled epitaxial growth strategy was demonstrated to synthesize nanocrystals of ZnSe, CdSe and PbSe with average diameters of 35 nm, 76 nm and 87 nm, respectively. The large ZnSe nanocrystals emitted pure blue light, which is important for display technology.