Self assembled organic nanocrystal superlattices

Abstract

A process for the preparation of a self assembled superlattice thin film of organic nanocrystal particles is described comprising: (i) combining one or more functional organic material to be precipitated as nanocrystal particles and one or more surface active material in a compressed COphase with a density of at least 0.1 g/cc, where the functional material is substantially insoluble in the compressed COin the absence of the surfactant, the surfactant comprises a compressed CO-philic portion and a functional material-philic portion, and the compressed COphase, functional material and surfactant interact to form an aggregated system having a continuous compressed COphase and a plurality of aggregates comprising surfactant and functional material molecules of average diameter less than 50 nanometers dispersed therein; (ii) rapidly depressurizing the compressed COphase thereby precipitating the dispersed functional and surfactant materials in the form of composite organic nanocrystals of average diameter less than 50 nanometers, and (iii) depositing the organic nanocrystals on a substrate surface, wherein the organic nanocrystals form a thin film having an ionic content of less than 0.001 M in equivalent sodium chloride concentration on the substrate surface, and the thin film exhibits a long range periodicity in the arrangement of the organic nanocrystals in a self assembled superlattice structure, as evidenced by x-ray diffraction.