Cation Exchange Combined with Kirkendall Effect in the Preparation of SnTe/CdTe and CdTe/SnTe Core/Shell Nanocrystals

Controlling the synthesis of narrow band gap semiconductor nanocrystals (NCs) with a high-quality surface is of prime importance for scientific and technological interests. This abstract presents facile solution phase syntheses of SnTe NCs and their corresponding core/shell heterostructures. Here, we synthesized monodisperse and highly crystalline SnTe NCs by employing an inexpensive, nontoxic precursor, SnCl₂, the reactivity of which was enhanced by adding a reducing agent, 1,2-hexadecanediol. Moreover, we developed a synthesis procedure for the formation of SnTe-based core/shell NCs by combining the cation exchange and the Kirkendall effect. The cation exchange of Sn²⁺ by Cd²⁺ at the surface allowed primarily the formation of SnTe/CdTe core/shell NCs. Further continuation of the reaction promoted an intensive diffusion of the Cd²⁺ ions, which via the Kirkendall effect led to the formation of the inverted CdTe/SnTe core/shell NCs.