Kinetically controlled assembly of cadmium chalcogenide nanorods and nanorod heterostructures

Abstract

While it is well understood that controlling anisotropic nanostructure growth can be accomplished by establishing kinetic growth conditions, the practical translation of this knowledge to access nanorods with a specific aspect ratio has not been realized. In this study we empirically determine the precursor consumption rates for growing nanorods and use this data to customize the size and shape of anisotropic nanostructures. The purpose of this work is to go beyond simply creating a set of growth conditions to obtain rods, dots, rice, and tetrapods by describing how to synthesize a nanomaterial of desired dimensions and aspect ratio in a pre-meditated fashion. Measured growth rates for model systems of CdSe (3.5 monomers rod⁻¹ s⁻¹ at 250 °C) and CdS nanorods (36 monomers rod⁻¹ s⁻¹ at 340 °C) were used to design elongated nanorods with enhanced aspect ratios and synthesize dot in rod CdS/CdSe and CdSe/CdS heterostructures. These model systems enable us to establish a rubric for the synthesis of customizable nanostructures and serve as a test case for understanding heterostructure assembly in colloidal systems.