| 초록 |
The goal of this study is to develop dielectric composites for capacitors which are suit for power electronic systems such as inverters in Hybrid Electric Vehicles (HEVs). Polymer-ceramic layered composite thin films consisting Poly(vilylidene fluoride-trifluoroethylene) and titanium dioxide were explored for the high voltage capacitor application. By arranging the two phases, which are electrically strong ferroelectric polymer phase and high dielectric constant ceramic phase, normal to the direction of the applied electric fields, the composite can exhibit high dielectric breakdown strength with improved dielectric permittivity. Solution derived thin film synthesis and PLD(Pulsed Laser Deposition) methods were employed to fabricate P(VDF-TrFE)/TiO2 bilayer composite thin film capacitors. With increasing volume fraction of the TiO2 layer, dielectric permittivity of the composite films were increased agreeing with the series mixing rule, while maintaining excellent breakdown resistance of the polymer phase under high electric fields. Coupling effects on the polarization behavior under high applied voltage resulted in substantially improved energy density and capacitance density of the composite film capacitors. Effects of volume fraction, crystallinity, and dielectric properties of the TiO2 layer on the polarization behavior of the composite films are discussed. |
