Nanocrystalline forms of metal oxides, including binary metal oxide, perovskite type metal oxides, and complex metal oxides, including doped metal oxides, are provided. Methods of preparation of the nanocrystals are also provided. The nanocrystals, including uncapped and uncoated metal oxide nanocrystals, can be dispersed in a liquid to provide dispersions that are stable and do not precipitate over a period of time ranging from hours to months. Methods of preparation of the dispersions, and methods of use of the dispersions in forming films, are likewise provided. The films can include an organic, inorganic, or mixed organic/inorganic matrix. The films can be substantially free of all organic materials. The films can be used as coatings, or can be used as dielectric layers in a variety of electronics applications, for example as a dielectric material for an ultracapacitor, which can include a mesoporous material. Or the films can be used as a high-K dielectric in organic field-effect transistors. In various embodiments, a layered gate dielectric can include spin-cast (e.g., 8 nm-diameter) high-K BaTiO.sub.3 nanocrystals and parylene-C for pentacene OFETs.
STATEMENT OF GRANT SUPPORT
 This invention was made with government support under award numbers DMR-0213574, CHE-011752, CHE-0641523, and ECCS-0644656 from the National Science Foundation (NSF) and award number DE-FG02-03ER15463 from the Department of Energy (DoE), and by the New York State Office of Science, Technology, and Academic Research (NYSTAR), and relied on equipment supported by the NSEC program of the National Science Foundation under Award Number CHE-0117752, and by a CAREER award, DMR-0348938. The government has certain rights in this invention.