Up to now, rechargeable batteries are mostly used for energy storage purposes. However, their electrochemical working principle limits the field of application. Capacitors with very high energy densities are an alternative approach for energy storage. They can be very quickly charged/discharged and have long lifetimes. We develop novel capacitors on the basis of 0-3 composites, where nanoparticles of perovskites are embedded in a matrix material. Specific organic and inorganic surfactants are used for coating of the nanoparticles. This coating enhances their uniform distribution in the matrix. The new materials combine the electrical advantages of ceramics and glasses/polymers (high permittivities and breakdown voltages) and can easily be processed as thin films.