Anuja Datta

A triboelectric generator based on self-poled Nylon-11 nanowires fabricated by gas-flow assisted template wetting

Triboelectric generators have emerged as potential candidates for mechanical energy harvesting, relying on motion-generated surface charge transfer between materials with different electron affinities. In this regard, synthetic organic materials with strong electron-donating tendencies are far less common than their electron-accepting counterparts. Nylons are notable exceptions, with odd-numbered Nylons such as Nylon-11, exhibiting electric polarisation that could further enhance the surface charge density crucial to triboelectric generator performance. However, the fabrication of Nylon-11 in the required polarised δ′-phase typically requires extremely rapid crystallisation, such as melt-quenching, as well as “poling” via mechanical stretching and/or large electric fields for dipolar alignment. Here, we propose an alternative one-step, near room-temperature fabrication method, namely gas-flow assisted nano-template (GANT) infiltration, by which highly crystalline “self-poled” δ′-phase Nylon-11 nanowires are grown from solution within nanoporous anodised aluminium oxide (AAO) templates. Our gas-flow assisted method allows for controlled crystallisation of the δ′-phase of Nylon-11 through rapid solvent evaporation and an artificially generated extreme temperature gradient within the nanopores of the AAO template, as accurately predicted by finite-element simulations. Furthermore, preferential crystal orientation originating from template-induced nano-confinement effects leads to self-poled δ′-phase Nylon-11 nanowires with higher surface charge distribution than melt-quenched Nylon-11 films, as observed by Kelvin probe force microscopy (KPFM). Correspondingly, a triboelectric nanogenerator (TENG) device based on as-grown templated Nylon-11 nanowires fabricated via GANT infiltration showed a ten-fold increase in output power density as compared to an aluminium-based triboelectric generator, when subjected to identical mechanical excitations.

Fully Printed Organic–Inorganic Nanocomposites for Flexible Thermoelectric Applications

Thermoelectric materials, capable of interconverting heat and electricity, are attractive for applications in thermal energy harvesting as a means to power wireless sensors, wearable devices, and portable electronics. However, traditional inorganic thermoelectric materials pose significant challenges due to high cost, toxicity, scarcity, and brittleness, particularly when it comes to applications requiring flexibility. Here, we investigate organic–inorganic nanocomposites that have been developed from bespoke inks which are printed via an aerosol jet printing method onto flexible substrates. For this purpose, a novel in situ aerosol mixing method has been developed to ensure uniform distribution of Bi2Te3/Sb2Te3 nanocrystals, fabricated by a scalable solvothermal synthesis method, within a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate matrix. The thermoelectric properties of the resulting printed nanocomposite structures have been evaluated as a function of composition, and the power factor was found to be maximum (∼30 μW/mK2) for a nominal loading fraction of 85 wt % Sb2Te3 nanoflakes. Importantly, the printed nanocomposites were found to be stable and robust upon repeated flexing to curvatures up to 300 m–1, making these hybrid materials particularly suitable for flexible thermoelectric applications.

Ferroelectric and piezoelectric oxide nanostructured films for energy harvesting applications

Perovskite oxide materials have been widely investigated due to properties related to their spontaneous polarization such as ferroelectricity, piezoelectricity, and pyroelectricity. Often due to high chemical stability, and mechanical robustness with large dielectric constants, ferroelectric and piezoelectric perovskite oxides have become essential components in a wide spectrum of applications such as nonvolatile random access memory, microelectromechanical devices, sensors, actuators, high-frequency electrical components, tunable microwave circuits, nanogenerators for energy harvesting, and as potential solar-cell absorbers. The realization of miniaturized devices has required these materials to be investigated in thin-film forms. However, research in ferroelectric and piezoelectric thin films is limited due to the intrinsic difficulties of structural engineering at the nanoscale. To this end, nanostructured films exhibit uniquely different properties from nontextured homogenous thin films due to the deliberate engineering of nanoscale features into the structure. Moreover, nanostructuring provides new insights into the size, shape, and surface effects on the charge-ordering in ferroelectric and piezoelectric perovskite oxide materials. The down-scaling effect results in an enhancement of the surface area of materials where surface charges play a dominant role in determining the magnitude and direction of polarization. As polarization properties are the cumulative phenomenon of crystal dimensions, orientation, and ordering, synthesis methodologies that can lead to the manipulation of size and dimensions of ferro- and piezoelectric nanostructures can offer great advantages. However, the large-scale synthesis and integration of ordered functional nanowires is a challenge, due to their complicated fabrication methodologies, high cost, and difficulties with phase stability in many metastable perovskite compounds. In this chapter we will review how facile solution-based synthesis processes can be utilized for fabricating state-of-the art and novel perovskite nanostructured films where tuning crystallinity and strain engineering due to interfacial effects, dimensional confinement, and domain wall interaction resulting from grain boundaries in nanostructures may enhance the Curie temperature, permittivity, or polarizability, and induce “self-poling” effects, eventually enhancing the overall performance of the devices. We will also consider the potential of some of the new ferroelectric nanostructures for photovoltaic applications, proposing pathways for coherent design of next-generation sustainable energy devices.

Research data supporting [Mapping piezoelectric response in nanomaterials using a dedicated non destructive scanning probe technique]

These files contain the raw data used to extract ND-PFM signals in Figure 2,3,4 of the manuscript. The MATALB code used to perform virtual lock-in operation is present.

Research Data Supporting "Structure and Thermoelectric Properties of Bi2-xSbxTe3 Nanowires Grown in Flexible Nanoporous Polycarbonate Templates"

Structural data and characterization (XRD, SEM, EDX). Transport measurements, including electrical conductivity and Seebeck coefficient.

Research data supporting [A Triboelectric Generator Based on Self-poled Nylon-11 Nanowires Fabricated by Gas-flow Assisted Template Wetting]

Research data supporting_Nylon NW TENG.zip file contains original SEM images and experimental data in the main text of the manuscript and supporting information. The original SEM images contain original scales and beam conditions at which SEM images were taken. raw-data.xlsx contains data files for the graphs, such as XRD, DSC, energy harvesting measurements and electrical characterization, discussed in the main text of the manuscript and the supporting information.

Research data supporting "Lead-Free Polycrystalline Ferroelectric Nanowires with Enhanced Curie Temperature"

Figures.zip file contains original SEM images and graphical images included in the main text and the supporting information of the manuscript. The original SEM images contain original scales and beam conditions at which SEM images were taken. SEM images in the manuscript and supporting information may have been taken as a whole or a part of the original images wherever apply. Likewise the scale in the manuscript images have been re‐drawn in order to enhance the clarity of the images, but depict true scale as they were in original. Data Files.zip contains data files for the graphs discussed in the main text and supporting information of the manuscript. Theoretical data. zip contains data file for the XRD plots and DFT theory for figure 5c and figure S1 asap

Research data supporting "Piezoelectric Nylon-11 Nanowire Arrays Grown by Template Wetting for Vibrational Energy Harvesting Applications"

Figures Text.zip file contains original SEM images and graphical images included in the main text of the manuscript. The original SEM images contain original scales and beam conditions at which SEM images were taken. SEM images in the manuscript may have been taken as a whole or a part of the original images wherever apply. Likewise the scale in the manuscript images have been re‐drawn in order to enhance the clarity of the images, but depict true scale as they were in original. Supporting Information.zip contains original SEM images and graphical images included in the supporting information. The original SEM images contain original scales and beam conditions at which SEM images were taken. SEM images in the manuscript may have been taken as a whole or a part of the original images wherever apply. Likewise the scale in the manuscript images have been re‐drawn in order to enhance the clarity of the images, but depict true scale as they were in original. Raw data.xlsx contains data files for the graphs discussed in the main text of the manuscript and the supporting information.