Recently, an approach for converting nanoscale mechanical energy into electrical energy has been suggested by using piezoelectric zinc oxide (ZnO) nanowire arrays. Such devices have been shown to convert ultrasonic energy into electric energy by a deflection of the nanowires via a corrugated electrode operated up and down by the ultrasound. A typical output power ~1pW for a device of area ~1mm2 and a density of nanowires ~107/mm2 can be obtained. In order to reach the power ~ 10nW needed to operate a nanodevice, nanogenerators of this kind need to be optimized. With the aim of fabricating low cost to efficiency ratio nanogenerators, we have considered ZnO films grown by an electrochemical technique, based on the direct precipitation of Zn or Ni hydroxides and TiO2 films by deposition starting form a colloidal suspension of anatase/rutile commercial powders, on a conducting ITO/glass substrate. These methods allowed us to obtain disordered but quite uniform arrays distributed on the surface of the substrate. Preliminary results on the electrical properties are presented. Under input mechanical strain we find output powers of order P~10-9/cm2 W, which are comparable to those obtained with the ZnO nanoarrays. Possible interpretations of results in terms of piezoelectricity (ZnO) and incipient ferroelectricity (TiO2) are presented and improvements of the devices are discussed.

Nanogenerators Based on ZnO or TiO2 Oxides

DALLACASA, Valerio;DI SIA, Paolo;
2010-01-01

Abstract

Recently, an approach for converting nanoscale mechanical energy into electrical energy has been suggested by using piezoelectric zinc oxide (ZnO) nanowire arrays. Such devices have been shown to convert ultrasonic energy into electric energy by a deflection of the nanowires via a corrugated electrode operated up and down by the ultrasound. A typical output power ~1pW for a device of area ~1mm2 and a density of nanowires ~107/mm2 can be obtained. In order to reach the power ~ 10nW needed to operate a nanodevice, nanogenerators of this kind need to be optimized. With the aim of fabricating low cost to efficiency ratio nanogenerators, we have considered ZnO films grown by an electrochemical technique, based on the direct precipitation of Zn or Ni hydroxides and TiO2 films by deposition starting form a colloidal suspension of anatase/rutile commercial powders, on a conducting ITO/glass substrate. These methods allowed us to obtain disordered but quite uniform arrays distributed on the surface of the substrate. Preliminary results on the electrical properties are presented. Under input mechanical strain we find output powers of order P~10-9/cm2 W, which are comparable to those obtained with the ZnO nanoarrays. Possible interpretations of results in terms of piezoelectricity (ZnO) and incipient ferroelectricity (TiO2) are presented and improvements of the devices are discussed.
Nanogenerators; Semiconductor Oxide Nanoarrays; Piezoelectricity; Photocatalytic Devices; Ferroelectrics; Electrodeposition; Cathodic Reduction; AFM Analysis; Indium-tin Oxide (ITO) thin Film
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11562/340794
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