Hybrid Structures for Piezoelectric Nanogenerators: Fabrication Methods, Energy Generation, and Self-Powered Applications

Smart energy harvesting through the surrounding environment generates sufficient energy to drive the low-power consumption systems. It is the forthcoming revolution in smart (or self-powered) technology and results in abolishing the usage of complex batteries, external circuit components, and natural sources. To date, extensive fabrication methods, the growth of ZnO nanostructures on plastic substrates, and flexible piezoelectric polymer film-based devices were tested to improve the performance of piezoelectric nanogenerator (PNG) as a prominent energy-harnessing approach for the development of sustainable independent power sources. Still, PNG technology suffers from brittleness, leakage current issues, high electrical output generation, and long-term durability, which can be possible to control by the composite technology, that is, polymer/nanoparticles. The objective of this book chapter determines the rapid growth of multifunctional, flexible composite structures through various methods (e.g., ionotropic gelation method, groove technique, ultrasonication followed by solution-casting methods) for high output energy generation and self-powered sensor/system studies

Novel piezoelectric paper based on SbSI nanowires

A novel piezoelectric paper based on antimony sulfoiodide (SbSI) nanowires is reported. The composite of tough sonochemically produced SbSI nanowires (with lateral dimensions 10–100 nm and length up to several micrometers) with very flexible cellulose leads to applicable, elastic material suitable to use in fabrication of, for example, piezoelectric nanogenerators. For mechanical energy harvesting, cellulose/SbSI nanocomposite may be used. Due to its high values of electromechanical coefficient (k33 = 0.9) and piezoelectric coefficient (d33 = 1 9 10-9 C/N), SbSI is a very attractive material for such devices. The preliminary investigations of a simple cellulose/SbSI nanogenerator for shock pressure (p = 3 MPa) and sound excitation (f = 175 Hz, Lp = 90 dB) allowed to determine its open circuit voltage 2.5 V and 24 mV, respectively. For a load resistance equal to source impedance (ZS = 2.90(11) MX), maximum output power density (PL = 41.5 nW/cm3 for 0.05-mm-thick sheet of this composite) of the cellulose/SbSI nanogenerator was observed. Cellulose/SbSI piezoelectric paper may also be useful to construct gas nanosensors and actuators

Paper-based ZnO self-powered sensors and nanogenerators by plasma technology

Nanogenerators and self-powered nanosensors have shown the potential to power low-consumption electronics and human-machine interfaces, but their practical implementation requires reliable, environmentally friendly and scalable, processes for manufacturing and processing. This article presents a plasma synthesis approach for the fabrication of piezoelectric nanogenerators (PENGs) and self-powered sensors on paper substrates. Polycrystalline ZnO nanocolumnar thin films are deposited by plasma-enhanced chemical vapour deposition on common paper supports using a microwave electron cyclotron resonance reactor working at room temperature yielding high growth rates and low structural and interfacial stresses. Applying Kinetic Monte Carlo simulation, we elucidate the basic shadowing mechanism behind the characteristic microstructure and porosity of the ZnO thin films, relating them to an enhanced piezoelectric response to periodic and random inputs. The piezoelectric devices are assembled by embedding the ZnO films in PMMA and using Au electrodes in two different configurations: laterally and vertically contacted devices. We present the response of the laterally connected devices as a force sensor for low-frequency events with different answers to the applied force depending on the impedance circuit, i.e. load values range, a behaviour that is theoretically analyzed. The vertical devices reach power densities as high as 80 nW/cm2 with a mean power output of 20 nW/cm2. We analyze their actual-scenario performance by activation with a fan and handwriting. Overall, this work demonstrates the advantages of implementing plasma deposition for piezoelectric films to develop robust, flexible, stretchable, and enhanced-performance nanogenerators and self-powered piezoelectric sensors compatible with inexpensive and recyclable supportsComment: 30 pages, 8 figures in main tex

Advanced Nanoelectromechanical Systems for Next Generation Energy Harvesting

The ever-increasing desire to produce portable, mobile and self-powered wireless micro-/nano systems (MNSs) with extended lifetimes has lead to the significant advancement in the area of mechanical energy harvesting over the last few years and it has been possible not only because has nanotechnology evolved as a powerful tool for the manipulation of matter on an atomic, molecular, and supramolecular scale, but also different micro-/nano fabrication techniques have enabled researchers and scientists to create, visualize, analyse and manipulate nano-structures, as well as to probe their nano-chemistry, nano-mechanics and other properties within the systems. The dissertation first discusses briefly about energy harvesting technologies for self-powered MNSs, for example a wireless aircraft structural health monitoring (SHM) system, with a particular focus on piezoelectric nanogenerators (PENG) and triboelectric nanogenerators (TENG) as they are the most promising approaches for converting ambient tiny mechanical energy into electrical energy efficiently and effectively and then it analyzes the theoretical and experimental methodologies for efficient energy harvesting using PENG, TENG and hybrid devices. The piezoelectric property intertwined with the semiconducting behaviour of different ZnO nanostructures has made them ideal candidate for piezoelectric energy harvesting, also intensive and state-of-the-art research has been going on to enhance the performance of the PENG devices based on 1D and 2D ZnO nanostructures. In this work, a high performance and consolidated PENG device based on the integration of ZnO nanowires and nanoplates on the same substrate has been demonstrated, that produces an output electrical power of 8.4 µW/cm2 at the matched load of 10MΩ that manifests their ability for powering up different MNSs. Since hybrid nanogenerators (HNG) integrate different types of harvesters in a single unit, where several energy sources can be leveraged either simultaneously or individually, in the next part of this work, a HNG device integrating PENG and TENG components has been designed, fabricated and characterized where PENG and TENG parts mutually enhance the performance of each other resulting an instantaneous peak power density of 1.864mW/cm2 and subsequently the device has been used to charge several commercial capacitors to corroborate their potential for aircraft SHM applications. Moreover, the hybrid device exhibits strong potential for wearable electronics as it can harvest energy from human walking and normal hand movements. However, successful implementation of self-powered electronics, such as a wireless aircraft SHM depends not only on the performance of individual parts but also on components integration within the system, where each device/system node within the network consists of a low-power microcontroller unit, high-performance data-processing/storage units, a wireless signal transceiver, ultrasensitive sensors based on a micro-/nano electro-mechanical system, and most importantly the embedded powering units. This dissertation aims to deepen the understanding of the different energy harvesting methods utilizing the knowledge of nanoscale phenomena and nanofabrication tools along with the associated prospects and challenges and thus, this research in the field of energy harvesting using advanced nano electro-mechanical systems could have a substantial impact on many areas, ranging from the fundamental study of new nanomaterial properties and different effects in nanostructures to diverse applications

Enhanced energy harvesting performance in lead-free multi-layer piezoelectric composites with a highly aligned pore structure

The harvesting of mechanical energy from our living environment via piezoelectric energy harvesters to provide power for next generation wearable electronic devices and sensors has attracted significant interest in recent years. Among the range of available piezoelectric materials, porous piezoelectric ceramics exhibit potential for both sensing and energy harvesting applications due to their reduced relative permittivity and enhanced piezoelectric sensing and energy harvesting figures of merit. Despite these developments, the low output power density and the lack of optimized structural design continues to restrict their application. Here, to overcome these challenges, a lead-free multi-layer porous piezoelectric composite energy harvester with a highly aligned pore structure and three-dimensional intercalation electrodes is proposed, fabricated and characterized. The effect of material structure and multi-layer configuration of the porous piezoelectric ceramic on the dielectric properties, piezoelectric response and energy harvesting performance was investigated in detail. Since the relative permittivity is significantly reduced due to the introduction of aligned porosity within the multi-layer structure, the piezoelectric voltage coefficient, energy harvesting figure of merit and output power are greatly enhanced. The multi-layer porous piezoelectric composite energy harvester is shown to generate a maximum output current of 80 μA, with a peak power density of 209 μW cm−2, which is significantly higher than other porous piezoelectric materials reported to date. Moreover, the generated power can charge a 10 μF capacitor from 0 V to 4.0 V in 150 s. This work therefore provides a new strategy for the design and manufacture of porous piezoelectric materials for piezoelectric sensing and energy harvesting applications.</p

Polarity in ZnO nanowires: A critical issue for piezotronic and piezoelectric devices

The polar and piezoelectric nature of the wurtzite structure of ZnO nanowires with a high aspect ratio at nanoscale dimensions is of high interest for piezotronic and piezoelectric devices, but a number of issues related to polarity are still open and deserve a particular attention. In this context, chemical bath deposition offers a unique opportunity to select the O- or Zn-polarity of the resultant nanowires and is further compatible with the fabrication processes of flexible devices. The control and use of the polarity in ZnO nanowires grown by chemical bath deposition opens a new way to greatly enhance the performance of the related piezotronic and piezoelectric devices. However, polarity as an additional tunable parameter should be considered with care because it has a strong influence on many processes and properties. The present review is intended to report the most important consequences related to the polarity in ZnO nanowires for piezotronic and piezoelectric devices. After introducing the basic principles involving crystal polarity in ZnO, a special emphasis is placed on the effects of polarity on the nucleation and growth mechanisms of ZnO nanowires using chemical bath deposition, defect incorporation and doping, electrical contacts and device properties

Self-adhesive electrode applied to ZnO nanorod-based piezoelectric nanogenerators

ZnO nanorod-based piezoelectric devices have gained wide attention in energy harvesting systems as they can be processed at low temperatures onto flexible plastic substrates, giving a good potential for low cost. However, the vacuum-evaporated, precious metal contacts remain a high-cost element of the devices. This paper discusses the use of transparent conductive adhesives (TCAs) as an alternative top contact that is free from both vacuum-evaporation and precious metals. TCA films of various thicknesses were tape-cast onto nickel microgrid on PET substrates and adhered using low-pressure cold-lamination to bond the adhesive component of the TCA to piezoelectric generators with the final device structure of PET/ITO/ZnO-seed/ZnO-nanorods/CuSCN/PEDOT:PSS/TCA. The piezoelectric performances of the devices were compared by measuring output voltage in open-circuit and maximum power output across a range of resistive loads. The voltage output was observed to rise with increasing TCA thickness, reaching a maximum value of 0.72 V generated with 110 µm of TCA as top contact. However, the higher resistance due to increased TCA thickness led to decreased power output; a maximum calculated power of 0.25 μW was obtained from the device with the thinnest TCA layer of 22 µm. Finally, the performance of piezoelectric nanogenerators with TCA contacts were compared to a control device with an evaporated gold contact

Optimization of zno nanorods concentration in a micro-structured polymeric composite for nanogenerators

The growing use of wearable devices has been stimulating research efforts in the de-velopment of energy harvesters as more portable and practical energy sources alternatives. The field of piezoelectric nanogenerators (PENGs) and triboelectric nanogenerators (TENGs), especially employing zinc oxide (ZnO) nanowires (NWs), has greatly flourished in recent years. Despite its modest piezoelectric coefficient, ZnO is very attractive due to its sustainable raw materials and the facility to obtain distinct morphologies, which increases its multifunctionality. The integration of ZnO nanostructures into polymeric matrices to overcome their fragility has already been proven to be fruitful, nevertheless, their concentration in the composite should be optimized to maximize the harvesters’ output, an aspect that has not been properly addressed. This work studies a composite with variable concentrations of ZnO nanorods (NRs), grown by microwave radiation assisted hydrothermal synthesis, and polydimethylsiloxane (PDMS). With a 25 wt % ZnO NRs concentration in a composite that was further micro-structured through laser engraving for output enhancement, a nanogenerator (NG) was fabricated with an output of 6 V at a pushing force of 2.3 N. The energy generated by the NG could be stored and later employed to power small electronic devices, ultimately illustrating its potential as an energy harvesting device.publishersversionpublishe

Flexible and Surface Modified ZnSnO3 Nanocubes for Enhanced Piezoelectric Power Generation and Wireless Sensory Application

Piezoelectric systems and their mechanisms are held in high regard, due to their cost-effective structure and mechanical proficiency to harvest renewable energy. In the present article, we propose an aluminum-doped zinc stannate (ZnSnO3) piezoelectric nanogenerator that can be employed for the harvest of energy and sensory applications. In order to ensure and further enrich the piezoelectric mechanics and product outcome in our device, ZnSnO3 was doped with 1 wt% to 5 wt% of aluminum nanoparticles. We reported that 2 wt% of aluminum-doped ZnSnO3 showed the highest electrical output in terms of open circuit voltages and short circuit current. The nanogenerator device achieved an average open-circuit voltage of 80 V to 175 V with a frequency range of 60 BPM to 240 BPM. This presented to be an unprecedented electrical output in comparison to period ZnSnO3-based piezoelectric nanogenerators. With the presented high output-to-size ration taken into consideration, the device was installed into a helmet as an energy harvester and wireless human motion sensor which can harvest energy as well as can detect and transmit signals from mechanical human movement. Thus, transmuting a regular helmet into a smart helmet- indicates a promising future for the field of piezoelectric sensors