Investigation into ameliorative dielectric properties of silicon/poly(vinylidene fluoride) composites by engineering insulating aluminum oxide shell as an interlayer

Flexible electronic materials with high-dielectric constant (e) and breakdown strength (E-b) but low loss is pursued. Encapsulation of conductive fillers with various insulating shells represents a promising strategy to inhibit dielectric loss or leakage current. In this work, aluminum oxide (Al2O3) encapsulated silicon (Si) core-shell structured particles were prepared through a sol-gel approach, and then were incorporated with poly(vinylidene fluoride) (PVDF). The dielectric properties of PVDF composites with various fillers are investigated under varying frequencies. The findings demonstrate that a Al2O3 shell was formed outside the original Si, and that the Si@Al2O3/PVDF exhibit a high e and elevated E-b but signally suppressive loss and restrained conductivity when compared with raw Si. The Al2O3 interlayer not only enhances the interface compatibility between the filler and the matrix and promotes interface polarizations, but also suppresses the loss and leakage current through preventing adjacent Si from directly contacting. The optimized dielectric performances can be achieved via tailoring the Al2O3 shell thickness. Furthermore, the theoretic fitting of experimental results by the Havriliak-Negami equation deciphers the Al2O3 interlayer' impact on the polarization mechanism. The resulting Si@Al2O3/PVDF composites with high e but low loss, as well as boosted E-b, reveal potential applications in electrical systems.