The magic-size nanocluster (CdSe)34 as a low-temperature nucleant for cadmium selenide nanocrystals; Room-temperature growth of crystalline quantum platelets

Abstract

Reaction of Cd(OAc)2·2H2O and selenourea in primary-amine/secondary-amine cosolvent mixtures affords crystalline CdSe quantum platelets at room temperature. Their crystallinity is established by X-ray diffraction analysis (XRD), high-resolution transmission electron microscopy (TEM), and their sharp extinction and photoluminescence spectra. Reaction monitoring establishes the magic-size nanocluster (CdSe)34 to be a key intermediate in the growth process, which converts to CdSe quantum platelets by first-order kinetics with no induction period. The results are interpreted to indicate that the critical crystal-nucleus size for CdSe under these conditions is in the range of (CdSe)34 to (CdSe)68. The nanocluster is obtained in isolated form as [(CdSe)34(n- octylamine)16(di-n-pentylamine)2], which is proposed to function as crystal nuclei that may be stored in a bottle. © 2014 American Chemical Society.