Controlled formation of 3D CdS nanocrystal superlattices in solution

Highly ordered 3D superlattices comprised of monodisperse CdS nanocrystals are formed rapidly in solution using a simple procedure. Control over the instigation of the superlattice crystallization process is demonstrated by adjusting the concentration of sulfur in solution. Transmission electron microscopy shows that the CdS nanocrystals are 7 nm in size and form well-ordered structures. Selected area electron diffraction of the superlattices reveals that the CdS nanocrystals have their crystal axes partially aligned. This is further confirmed using a fast Fourier transform analysis of high-resolution transmission electron micrographs.