Engineered thiol anchored Au-BaTiO3/PVDF polymer nanocomposite as efficient dielectric for electronic applications

In modern electronic and electric appliances industries, polymer nanocomposites-based capacitors comprising of high dielectric constant ceramics (eg. BaTiO3 (BT), SrTiO3, CaCu3Ti4O12, etc.) and polymers (eg. polyvinylidene fluoride (PVDF), polyethylene terephthalate (PET), polycarbonate (PC), etc.) are becoming attractive for electrical energy storage applications. High dielectric constant fillers improve the energy density of the capacitors but at the cost of decreased efficiency, large dielectric loss as well as electrical conduction at high fields. In this paper, we present a novel dielectric core-satellite BT-gold (Au) nanoparticles (NPs) for high energy density capacitor application. Hydroxylated BT NPs (BTO NPs) were immobilized with Au NPs of size 4 nm and were used as fillers into PVDF polymer matrix. The results show that the incorporation of Au on BT NPs improved the dielectric constant, energy density as well as efficiency, while reduction in the dielectric loss. To further improve the dielectric properties, Au-BTO NPs were coated with 2,3,4,5,6-Pentafluorothiophenol (PFTP) layer. The dielectric properties were further tuned with different PFTP concentrations. The PFTP serves as the bridge between NPs and PVDF polymer by forming hydrogen bonding. The dielectric properties were measured at two different PFTP concentrations (PFTP1 and PFTP1.5, where 1 and 1.5 refer to the molar ratios of PFTP and Au decorated BT NPs). The lower PFTP concentration results in improved dielectric properties while increasing the concentration decreases the overall performance of the capacitors. The energy density of PFTP1-Au-BTO/PVDF was 2.04 J cm(-3) at 2100 kV cm t which was 21% higher than that of PVDF and 70% higher than biaxially oriented polypropylene (BOPP), a present state-of-the-art dielectric polymer. Thus, the combination of both, Au decoration on BT NPs and hydrogen bonding of PFTP with PVDF chains are responsible for improved dielectric properties and make these nanocomposites a promising candidate for energy storage applications.