PVDF nanofibers are prepared using electrospinning. The effect of addition of a hydrated salt, nickel chloride hexahydrate (NiCl(2)·6H(2)O), on the phase formation is examined. Addition of the hydrated salt (NC) is found to enhance the polar β phase by about 30%. The peak to peak piezo-voltage generated for PVDF NC is almost 0.762 V, a factor of 3 higher than that for PVDF. The fiber mats exhibit a significantly enhanced dynamic strain sensor response. The voltage generated per unit micro-strain developed during the free vibration test for PVDF was 0.119 mV whereas it was 0.548 mV for PVDF NC, exhibiting a non-linearly enhanced performance vis a vis the increase in the β phase component.

A good high rate supercapacitor performance requires a fine control of morphological (surface area and pore size distribution) and electrical properties of the electrode materials. Polyaniline (PANI) is an interesting material in supercapacitor context because it stores energy Faradaically. However in conventional inorganic (e.g. HCl) acid doping, the conductivity is high but the morphological features are undesirable. On the other hand, in weak organic acid (e.g. phytic acid) doping, interesting and desirable 3D connected morphological features are attained but the conductivity is poorer. Here the synergy of the positive quality factors of these two acid doping approaches is realized by concurrent and optimized strong-inorganic (HCl) and weak-organic (phytic) acid doping, resulting in a molecular composite material that renders impressive and robust supercapacitor performance. Thus, a nearly constant high specific capacitance of 350 F g−1 is realized for the optimised case of binary doping over the entire range of 1 A g−1 to 40 A g−1 with stability of 500 cycles at 40 A g−1. Frequency dependant conductivity measurements show that the optimized co-doped case is more metallic than separately doped materials. This transport property emanates from the unique 3D single molecular character of such system.

An electrospun fiber based wearable organic–inorganic hybrid piezo‐nanogenerator compose of suitably engineered P(VDF‐TrFE) and BaTiO3 nanostructures is reported. In the case of the device with an electrospun mat of piezoelectric β‐phase P(VDF‐TrFE) and BaTiO3 nanoparticulates filled in the interfiber open spaces, a power density of 16 μW cm−2 is realized at an applied impact of 0.02 MPa (which essentially corresponds to the thumb pressure). A similar device, with BaTiO3 additionally embedded in the P(VDF‐TrFE) fibers during their formation, renders a significantly higher peak power density of 28 μW cm−2 with instantaneous power density of ≈8.8 μW cm−2 at the same touch pressure. This performance is attributed to the high density of interfaces in such a device and the corresponding enhancement in the dielectric response. It is demonstrated that the power generated from such a hybrid device structure can be used for small scale applications such as charging a mobile phone.

Flexural strain fields are encountered in a wide variety of situations and invite novel device designs for their effective use in sensing, actuating, as well as energy harvesting (nanogenerator) applications. In this work we demonstrate an interesting all-organic device design comprising an electrospun P(VDF-TrFE) fiber-mat built directly on a conducting PANI film, which is also grown on a flexible PET substrate, for flexural piezo-FET and nanogenerator applications. Orders of magnitude stronger modulation of electrical transport in PANI film is realized in this device as compared to the case of a similar device but with a uniform spin-coated P(VDF-TrFE) film. We find that in the flexural mode of operation, the interaction between the laterally modulated nanoscale strain field distributions created by the fibers and the applied coherent strain field strongly influences the carrier transport in PANI. The transport modulation is suggested to occur due to strain-induced conformational changes in P(VDF-TrFE) leading to changes in carrier localization-delocalization. We further show that the fiber-mat based device system also works as an efficient nanogenerator capable of delivering power for low power applications.

A uniformly dense dispersion of few layer BP (FLBP) nanosheets in PDMS (polydimethylsiloxane) matrix is shown to exhibit a remarkably strong mechanical energy harvesting effect with highest peak-to-peak voltage output of about 350 V.