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INTRODUCTION TO THE NEWFIELD OF

NANOPIEZOTRONICS

AND ITS APPLICATION IN

NANOGENERATORS

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Contents

What is NANOPIEZOTRONICS

Materials that show Nanopiezoelectricity

Principle of Nanopiezotronics

Application in NANAOGENERATORS

Future scope

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Nanopiezotronics

Nano : derived from Greek word meaning "dwarfdenoting a factor of 109

Piezo : means to squeeze or to press

-tronics : a suffix referring to a device, tool, orinstrument

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Piezoelectric effect

Definition: ability of some materials to generate anelectric potential in response to applied mechanicalstress.

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A question of structure

Centrosymmetry Non-centrosymmetry

Ref. [2]

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Which material?

In nature :

- Quartz

- Topaz

- Cane sugar

- Bones

Human-made :

- some crystals

- even some polymers

- but mainly ceramics

in particular :ZnO

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ZnO (Zinc Oxide)

Structure

Comes in two differenttypes ofcrystal

Blende Wurtzite

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Wurtzite

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ZnO : the perfect material

WHY ZnO?

ZnO is a wide-band gap(3.37 eV) semiconductor that

has huge potential for electronic, optoelectronic, andoptical applications.

It can tolerate large amounts of deformation withoutdamage

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These are biocompatible, allowing theiruse in the body without toxic effects.

ZnO has polar surfaces. The electrostatic

interaction energy and distinct chemicalactivities of the polar surfaces results inthe formation of a wide range ofstructures, such as

Nanowires, Nanorings, Nanobelts, andNanohelices.

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Principle of Nanopiezotronics

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Nanogenerator Principles

Piezoelectric effect

Stress electric field/potential distribution

Ref. [10]

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Nanowire contacts

Bottom ohmic contact:

work function < electron affinity of ZnO

Top Contact: Schottky diode:work function > electron affinity of ZnO

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Potential build up and discharge made possible by theSchottky barrier

Ref. [10]

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Direct current Nanogenerator driven by

ultrasonic waves

AFM tip replaced by zigzag electrode

Vertically aligned array of ZnO NW

Ref. [11]

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Different configuration possibilities of the NW in respect

to the zigzag electrode

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Upcoming Technology

Researchers at Georgia Tech are developing apower shirt capable of running portable electronic

gadgets. Clothing woven with fibers containingmicroscopic nanogenerators will use piezoelectric

effects to convert the wearers movements intoelectrical energy.

According to Georgia Tech, the nanogenerator-

impregnated fibers could also find use in curtains,tents, and other flexible structures, enabling theharvesting of energy from wind motion, sound

vibration, or other mechanical energy.