Spontaneous shape and phase control of colloidal ZnSe nanocrystals by tailoring Se precursor reactivity

Abstract

Herein we demonstrated that the shape and phase of colloidal ZnSe nanocrystals can be spontaneously tuned through tailoring the selenium precursor reactivity in a phosphine-free reaction system. Selenium species with diverse reaction activities, i.e. Se₂²⁻ or Se²⁻, were produced by the addition of different volumes of reductant superhydride (lithium triethylborohydride). Theoretical calculation of ΔG_r indicates that superhydride-reduced Se₂²⁻ is less active than Se²⁻ for the reaction with a Zn precursor. Nanoparticle growth using Se₂²⁻ produces wurtzite ZnSe nanorods whereas the reaction of more reactive Se²⁻ with the zinc precursor leads to the formation of spherical zinc blende ZnSe nanodots. This work not only provides a facile synthetic approach for the preparation of high quality ZnSe nanocrystals but also gives insights into the shape and phase control of other colloidal nanocrystals.