Quantifying Energy Harvested from Contact-Mode Hybrid Nanogenerators with Cascaded Piezoelectric and Triboelectric Units

� 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim This paper presents an investigation of novel contact-mode hybrid nanogenerators comprising cascaded piezoelectric and triboelectric units. For the first time, a theoretical analysis of the contact-mode hybrid generator is presented to describe the relationships among transfer charges, voltage, current, and average output power in terms of material properties, hybrid generator structural parameters, harvesting, and operational conditions. New hybrid generators with much enhanced piezoelectricity are fabricated via a simple, room-temperature, cost-effective route by using nonwoven fabrics made from electrospun Polyvinyledenedifluoride-trifluoroethylene (PVDF-TrFE)/Ag nanowire nanofibers and Polydimethylsiloxane (PDMS) composites with graphite nanoparticles. The results provide a powerful tool for synthesis and selection of materials, design and optimization of the configuration, and operation of such kind of hybrid generators as well as determination of the value of external capacitor.