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

Abstract

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.

In Situ Polarized Ultrathin PVDF Film-Based Flexible Piezoelectric Nanogenerators

“…are used in PNGs owing to their advantages overcoming brittleness, failure instability, and lower force limits of inorganic PNG devices. 1,17,18 Since PVDF has low d 33 and dielectric constant (ε), it is often blended with various inorganic nanofillers with high d 33 for an enhancement in the device performance. 19,20 In addition, processes such as mechanical stretching, electrospinning, solution casting, quenching, etc.…”

“…7,20,27 Also, in these devices, owing to the sandwiching, air gaps might be introduced into the active layer, resulting in the formation of tiny triboelectric nanogenerators that might adversely affect the device output. 1 Furthermore, the blends/composites of inorganic nanofiller− PVDF devices 19 A few recent studies 20,27 on PNGs have also reported avoidance of electrical poling step through the use of two-dimensional (2D) nanomaterials such as n-graphene, SnO 2 nanosheets, etc. to fabricate self-poled or self-oriented dipole devices; however, they had to construct a multilayer structure to observe the piezoelectric phenomenon.…”

“…are considered to be important components for realizing self-powered devices. Moreover, recent developments in materials science, mechanics, and manufacturing now enable the construction of piezoelectric devices in formats that are thin, flexible, and, in some cases, mechanically stretchable. − Down the line, there are a series of organic and inorganic materials that can be directly implemented for the piezoelectric action. High-performance piezoelectric nanogenerators (PNGs) based on inorganic piezoelectric materials such as zinc oxide (ZnO), barium titanate (BTO), − lead zirconate titanate, − etc.…”

“…On the other hand, organic polymers such as poly­(vinylidene fluoride) (PVDF), poly­(tetrafluoroethylene) (PTFE or Teflon), Nylon-11, etc. are used in PNGs owing to their advantages overcoming brittleness, failure instability, and lower force limits of inorganic PNG devices. ,, Since PVDF has low d 33 and dielectric constant (ε), it is often blended with various inorganic nanofillers with high d 33 for an enhancement in the device performance. , In addition, processes such as mechanical stretching, electrospinning, solution casting, quenching, etc. are also explored to enhance the β phase of the active material. − …”

“…In consideration with the architecture of the devices reported, most piezoelectric nanogenerators are formed by either sandwiching the free-standing PVDF films between partially cured PDMS or adding inorganic nanoparticles, thereby increasing the complexity of the fabrication, which results in thick-film devices. ,, Also, in these devices, owing to the sandwiching, air gaps might be introduced into the active layer, resulting in the formation of tiny triboelectric nanogenerators that might adversely affect the device output . Furthermore, the blends/composites of inorganic nanofiller–PVDF devices require high electric field poling to align the H–F dipoles across C–C chain in one direction.…”