Fabrication of Piezoelectric ZnO Nanowires Energy Harvester on Flexible Substrate Coated with Various Seed Layer Structures

Abstract

Flexible piezoelectric nanogenerators (PENGs) are very attractive for mechanical energy harvesting due to their high potential for realizing self-powered sensors and low-power electronics. In this paper, a PENG that is based on zinc oxide (ZnO) nanowires (NWs) is fabricated on flexible and transparent Polydimethylsiloxane (PDMS) substrate. The ZnO NWs were deposited on two different seed layer structures, i.e., gold (Au)/ZnO and tin-doped indium-oxide (ITO)/ZnO, using hydrothermal synthesis. Along with the structural and morphological analyses of ZnO NWs, the electrical characterization was also investigated for ZnO NWs-based flexible PENGs. In order to evaluate the suitability of the PENG device structure, the electrical output performance was studied. By applying a periodic mechanical force of 3 N, the ZnO NWs-based flexible PENG generated a maximum root mean square (RMS) voltage and average power of 2.7 V and 64 nW, respectively. Moreover, the comparison between the fabricated device performances shows that a higher electrical output can be obtained when ITO/ZnO seed layer structure is adopted. The proposed ZnO NWs-based PENG structure can provide a flexible and cost-effective device for supplying portable electronics.

Piezo‐Semiconductor Coupled Model for the Simulation of Zinc Oxide 1–3 Piezo‐Composite

“…In literature, experimental works on NGs have been described using various thicknesses of polymer as a capacitive layer but also different polymers: 1 µm of PMMA, [ 30 ] 7 µm of PDMS, [ 38 ] 300 nm of Parylene C. [ 8 ] It could be interesting to study experimentally the influence of the thickness of the same polymer deposited on equivalent ZnO NWs arrays.…”

“…where j n,3 is the electron current density z-component, n the electron density, q the elementary charge, 𝜇 n,33 the electron mobility zz-component and D n,33 the electron diffusion coefficient zzcomponent. These 1D equations are coupled to Newton's law (Equation 6), Gauss's law (Equation 7), and the charge conservation Equation (8):…”

“…In most NGs, ZnO NWs are embedded in a polymer matrix that may be PMMA, [31] PDMS, [37,38] or Parylene C, [8] both to increase the mechanical robustness and prevent internal discharges between adjacent NWs. This design can be seen as a 1-3 piezocomposite, concept introduced by Newnham et al in 1978, [39] the main difference being the imperfect alignment of ZnO NWs orthogonally to the substrate.…”

A Review on Epidermal Nanogenerators: Recent Progress of the Future Self‐Powered Skins

“…[71][72][73][74] As for the inorganic piezoelectric materials, ZnO, GaN, BaTiO 3 , and lead zirconate titanate (PZT) have been heavily explored. [75][76][77][78][79] In particular, nanostructured ZnO has been widely studied. [80][81][82] Thanks to their flexibility, ZnO nanowires are often used for fabricating epidermal devices.…”

ZnO Thin Films Growth Optimization for Piezoelectric Application

“…ZnO has the advantage that it can be easily grown along its c-axis and in the form of a variety of nanostructures [ 3 , 4 ]. This fact has pushed the interest for this material in the field of sensors [ 5 , 6 , 7 ], actuators [ 8 , 9 ], and nanogenerators [ 10 , 11 ], in spite of the fact that the d 33 coefficient is still about one order of magnitude lower than that of other common piezoelectric ceramic compounds [ 12 ]. In these applications, the typical ZnO film thickness is in the range of micrometers, with a maximum reported piezo response of tens of pm/V for an oriented or composite film [ 13 , 14 , 15 ], and up to 240 pm/V for V-doped ZnO [ 16 , 17 ].…”