Optical properties of CdSe superlattices

Three-dimensional, faceted assemblies of CdSe nanocrystals were grown to microscopic sizes sufficient for identification and direct characterization. Analyses made by optical, fluorescence, and transmission electron microscopy showed that individual, faceted superlattices are composed of nearly single-size nanocrystals assembled into fee lattices. Photoluminescence was measured in individual superlattices, and the results were compared to the same measurements made in amorphous solid layers and solutions of nanocrystals. Differences in the shape and peak positions of photoluminescence spectra are explained by energy transfer processes determined by nanocrystal size distribution, structure of solid layers, and presence of aggregates in solutions.