Enhancement of Photoswitchable Dielectric Property by Conducting Electron Donors on Plasmonic Core–Shell Gold-Fluorenyl C₆₀ Nanoparticles

A new nanomaterial design was made by the construction of a tetralayered core–shell configuration, containing a magnetic core of nanospherical γ-FeO_x particle (NP) encapsulated by one plasmonic gold subshell, one middle layer of electron-polarizable C₆₀(>DPAF-C_n)_x-derived fullerosome membrane, and an outer shell of organic electron donors. This class of multilayered core–shell nanospherical materials was recently reported to be excellent microwave absorbers. We found that this analogous of multilayered NPs was capable of inducing photoswitchable dielectric property (permittivity) amplification at the microwave frequency range of 1.0–4.0 GHz. The enhanced phenomena were further investigated by the use of six variable organic molecular electron donors and two conducting conjugated polymers, serving as the supply of photoinduced transferrable electrons at the outer shell layer, for comparison. The design largely increased the number of polarizable charges, leading to a maximum of 387% amplification of the relative dielectric constant (ε_r^′) value or a 159% additional increase from that of the parent trilayered precursor NPs without organic donors. The latter percentage increase of ε_r^′ was contributed from the application of electron-donating hexamethylenetetraselenafulvalene molecules. Good recyclability of relative complex dielectric properties (ε_r^′ and the derivative ε_r^″) back to their original values during each photoactivation cycle of light-on and light-off manipulations may allow the potential nanomaterial uses as photoswitchable dielectrics in the modulation of microwave reflection signals.