Patent ID: 7097902

Claim:
A process for the preparation of a self assembled superlattice thin film of organic nanocrystal particles 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 CO 2 phase with a density of at least 0.1 g/cc, where the functional material is substantially insoluble in the compressed CO 2 in the absence of the surfactant, the surfactant comprises a compressed CO 2 -philic portion and a functional material-philic portion, and the compressed CO 2 phase, functional material and surfactant interact to form an aggregated system having a continuous compressed CO 2 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 CO 2 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.