ZnO/PDMS nanocomposite generator: Interphase influence in the nanocomposite electro-mechanical properties and output voltage

Nanocomposite generators convert mechanical energy into electrical energy and are attractive low-power solutions for self-powered sensors and wearables. Homogeneous dispersion, high concentration, and orientation of the embedded filler strategies have been assumed to maximize the voltage output in nanocomposite generators. This work contrast these assumptions by studying the dominance of the interphase in low filler concentrations (¡10%) and random dispersions in a ZnO/PDMS nanocomposite generator with high peak-to-peak voltage generation capabilities (≈150V). The interphase in the nanocomposite was studied by the analysis of the random dispersion of the nanocomposite through the estimation of the effective volume fraction (ϕ_agg) which allowed us to identify three levels of interaction: individual interphases, interacting interphases, and overlapping between NPs and interphases. The interacting interphase is responsible here for the high generated voltage. In addition, the impact of the interphase was studied by applying lumped element (LE) and interphasial power-law (IPL) models that capture the measured voltages and the electromechanical film properties. The obtained results justify that engineering of interphases could be a design strategy for high voltage generation.