Surfactant-Modified Nanocomposite Thin-Film Capacitors

This paper discusses the potential and importance of interface engineering of barium titanate nanoparticles for dielectric capacitors. The BaTiO3 nanoparticles were dispersed in a polypropylene gel with the aid of two types of surfactants: an ionic sodium dodecyl sulfate (SDS) and a nonionic Triton X-100. Optical microscopy and light scattering analyses revealed a notable decrease in nanoparticle agglomeration within the polypropylene gel when surfactants were employed, which could reach the diameter of a single nanoparticle. Dielectric capacitors were manufactured through multi-layer spin coating. The capacitor comprised top and bottom layers of neat polypropylene with three intermediary nanocomposite layers. Comparative analysis showcased a 37% increase in the dielectric constant of capacitors utilizing the ionic surfactant compared to the nonionic alternative, and a 23% increase over the devices without any surfactant. Conversely, the incorporation of the nonionic surfactant resulted in a 140% surge in dielectric strength compared to devices with the ionic surfactant. Overall, devices with the nonionic surfactant exhibited an energy density exceeding four times that of the ionic surfactant, and double that of biaxially oriented or spin-coated polypropylene devices. Thus, interface engineering emerges as a promising and efficient strategy for enhancing nanoparticle dispersibility in polypropylene, consequently elevating the energy density of film capacitors.