Poly­(vinylidene fluoride) (PVDF)-based piezoelectric materials are promising candidates for sensors, transducers, and actuators, due to several distinctive characteristics such as good flexibility, easy processability, and high mechanical resistance. In the present work, PVDF-based nanocomposites loaded with BaTiO3 nanoparticles (NPs) of various weight fractions were prepared by the electrospinning technique and used for the fabrication of a flexible piezoelectric pressure tactile sensor (PPTS). The addition (5, 10, and 20 wt %) of piezoelectric BaTiO3 NPs improves the piezoelectric performance, especially the β phase crystals of PVDF/BaTiO3 (10 wt %) nanocomposites that can reach 91.0%. In addition, the mechanical strength of PVDF/BaTiO3 nanocomposites is up to 26.7 MPa, which is an increase of 66% compared to neat PVDF. It should be emphasized that the elongation at break continuously increases from 71% to 153% with increasing BaTiO3 NPs. More importantly, the PPTS (piezoelectric pressure tactile sensor) with the combination of electrospun PVDF/BaTiO3 nanocomposite membranes and polydimethylsiloxane (PDMS) displays excellent flexibility and linear response to external mechanical force. The flexible PPTS devices capable of detecting different music sounds have potential uses in wide fields, such as voice recognition, speech therapy, and ultrasound imaging.

A novel flexible zinc oxide/poly­(vinylidene fluoride) (ZnO/PVDF) nanocomposite was prepared by electrospinning for fabricating a piezoelectric nanogenerator (PNG). The ZnO nanoparticles (NPs) and nanorods (NRs) were used as nanofillers of piezoelectric PVDF to prepare fibrous nanocomposite membranes. It has been found that the addition of piezoelectric ZnO NPs and NRs can improve the overall performance of the PNGs fabricated with the electrospun membranes. A large electrical throughput (open circuit voltage ∼85 V and short circuit current ∼2.2 μA) from the ZnO NR/PVDF fiber membrane-based PNG (ZR-PNG) indicates that ZnO NRs are effective functional fillers for PVDF. The high aspect ratio and flexibility characteristics of ZnO NRs were found to be highly beneficial for improving the piezoelectric properties of the nanocomposites. ZnO NRs act as nucleating agents of β-phase PVDF, and ZnO NRs can also produce piezoelectric charges when they deform with the composite fibrous membrane. It has been concluded that the obvious synergistic effects between the piezoelectric nanofillers and electroactive β-crystals of PVDF in the ZnO NRs/PVDF composites are useful for the construction of the high-performance flexible PNG. In addition, the fabricated ZR-PNG can light up commercial light emitting diodes (40 white, 36 blue) and charge the capacitors in a very short time (3 V is accomplished in 25 s), which indicates the potential of the ZR-PNG for portable, wearable, flexible, or self-powered electronic devices.

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We fabricate a kind of flexible electrochromic (EC) film by spraying the mixed dispersion of silver nanowires (AgNWs) and poly (3, 4-ethylenedioxythiophene) (PEDOT) on the graphene (GR) electrode. AgNWs are embedded in the PEDOT nanoparticles, forming an interlaced conductive network and double electron transport channels; therefore, the disadvantages of poor conductive GR electrodes have been remedied effectively. The subsequent GR-based PEDOT/AgNWs composite films have revealed remarkable optical contrast (63%), high coloration efficiency ( 182.8 c m 2 C − 1 ), and good cycle stability (keeping the optical contrast about 60% after switching cycles of 16,000 s). In addition, the GR-based composite films can keep good EC performance after 2000 cycles of bending tests, while those of the ITO/PET-based composite films decrease dramatically. The ultraflexible GR-based PEDOT/AgNWs composite films with excellent EC properties present an opportunity for fabricating large-area flexible EC devices.