Multilayer polyetherimide films incorporating alumina nanolayers for dielectric capacitors

Multilayer dielectrics have attracted considerable attention in the last decade due to the enhanced electrical property and the promise for industry application. Thinner films with ultrahigh dielectric performance are yet to be designed. Herein, the ultrathin Al₂O₃ /PEI multilayer composite films are deliberately fabricated by combining the solution casting and atomic layer deposition techniques. The multilayer polymer constructed with 3-layer nano Al₂O₃ exhibits an ultrahigh breakdown strength (>800 kV/mm) and charge energy density (8.59 J/cm³) with high efficiency (93.8%). Counterintuitively, the hetero polyetherimide/alumina form a seamless interface revealed by a transmission electron microscope. The complementary molecular-dynamic calculation indicates the negative formation energy between the organic and inorganic interface to support the formation mechanism. Finite-element simulation reveals the reason for dielectric-breakdown enhancement from electrical field weakening and rapid heat dissipation assisted by the alumina layer. This ultrathin hetero multilayer composite strategy provides a pathway for the design and investigation of competitive heteropolymers and inorganics combinations.