| This thesis describes the surface modification of barium titanate nanoparticles and their application to high quality, solution-processable polymer/ceramic dielectric nanocomposites with improved dielectric properties. Phosphonic acid-based ligands were found to yield a high surface coverage and robust surface modification on the surface of barium titanate nanoparticles. The study on the dielectric properties of the nanocomposites utilizing surface-modified barium titanate nanoparticles is presented by systematically changing the materials parameters, such as the nanoparticle volume fraction, the host permittivity, and the size of the nanoparticles. The dielectric properties of the nanocomposites were examined by fabricating parallel-plate capacitors and organic field-effect transistors and characterizing their electrical performances. A new model combining effective medium theory and finite difference simulation is proposed to explain the experimentally observed behaviors of the nanocomposites especially at high volume fractions where the porosity in the nanocomposites becomes significant. The new nanocomposite materials presented in this study are potentially useful as dielectrics for high-energy-density capacitors and gate insulators in organic field-effect transistors. |
