Self assembled organic nanocrystal superlattices

摘要

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 CO₂ phase with a density of at least 0.1 g/cc, where the functional material is substantially insoluble in the compressed CO₂ in the absence of the surfactant, the surfactant comprises a compressed CO₂-philic portion and a functional material-philic portion, and the compressed CO₂ phase, functional material and surfactant interact to form an aggregated system having a continuous compressed CO₂ phase 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 CO₂ phase 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.