Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire Arrays Zhong Lin Wang1,2,3* and Jinhui Song1 14 APRIL 2006 VOL 312 SCIENCE - PowerPoint PPT Presentation

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Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire Arrays Zhong Lin Wang1,2,3* and Jinhui Song1 14 APRIL 2006 VOL 312 SCIENCE

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Title: Piezoelectric Nanogenerators Based on Zinc Oxide Nanowire Arrays Zhong Lin Wang1,2,3* and Jinhui Song1 14 APRIL 2006 VOL 312 SCIENCE


1
Piezoelectric Nanogenerators Basedon Zinc Oxide
Nanowire ArraysZhong Lin Wang1,2,3 and Jinhui
Song114 APRIL 2006 VOL 312 SCIENCE
  • Presented by
  • Yiin-Kuen(Michael) Fuh

2
Outline
  • Motivation Background
  • Experimental design
  • Results
  • Conclusion

3
Motivation Background
  • Motivationself-powered device can greatly reduce
    the size of integrated nanosystems for
    optoelectronics, biosensors and more.
  • Background
  • 1D ZnO nanomaterials
  • exhibits both semiconducting and
    piezoelectric(PZ) properties for
    electromechanically coupled sensors and
    transducers.
  • is relatively biosafe and biocompatible for
    biomedical applications.
  • exhibits the most diverse and abundant
    configurations of nanostructures knownsuch as
    NWs, nanobelts (NBs) ,nanosprings, nanorings,
    nanobows and nanohelices (10).
  • The mechanism of the power generator relies on
    the coupling of piezoelectric and semiconducting
    properties of ZnO as well as the formation of a
    Schottky barrier between the metal and ZnO
    contacts.

4
Experimental design
  • Aligned ZnO NWs grown on -Al2O3 substrate.
  • (B) TEM image showing the NW without an Au
    particle or with a small Au particle at the top.
    Each NW is a single crystal and has uniform
    shape. Inset at center an electron diffraction
    pattern from a NW. Most of the NWs had no Au
    particle at the top. Inset at right image of a
    NW with an Au particle
  • (C) The base of the NW is grounded and an
    external load of RL is applied, which is much
    larger than the resistance RI of the NW. The AFM
    scans across the NW arrays in contact mode

Experimental design for converting nanoscale
mechanical energy into electrical energy by a
vertical piezoelectric (PZ) ZnO NW.
5
Results-Electromechanically coupled discharging
process observed in contact mode.
  • (A) Topography image, NW density 20/um2
  • (B) Output voltage , Vpeak6-9mV
  • (C) A series of line profiles of the voltage
    output signal when the AFM tip scanned.
  • (D) Line profiles from the topography (red) and
    output voltage (blue) images across a NW. The
    peak of the voltage output corresponds
    approximately to the maximum deflection of the
    NW, indicating that the discharge occurs when the
    tip is in contact with the compressed side of the
    NW.
  • (E)Vpeak of FWHM .
  • (F) WelasticWPZDWvib. , WPZD0.5CV2
  • ?WPZD/Welastic 17-30

6
Results-Electromechanically coupled discharging
process observed in tapping mode.
  • (A) Experimental setup.
  • (B) Topography image
  • (C) Output voltage. The voltage output contains
    no information but noise, proving the physical
    mechanism demonstrated

7
Theory --Transport is governed by a
metal-semiconductor Schottky barrier for the PZ
ZnO NW
  • (A) NW coordination system.
  • (B) Longitudinal strain z distribution (NW of
    length 1 µm and an aspect ratio of 10).
  • (C) induced electric field Ez distribution
  • (D) Potential distribution due to PZ effect.
  • Schottky rectifying behavior (E) is to separate
    and maintain the charges as well as build up the
    potential. The process in (F) is to discharge the
    potential and generates electric current.
  • The PZ potential is built up in the displacing
    process (G), and later the charges are released
    through the compressed side of the NW (H).
  • (I) Large Au particle The charges are gradually
    "leaked" out, no accumulated potential will be
    created.

8
Conclusion
  • Self-powering nanotechnology ? Estimated power
    10 pW/µm2 and much more power if drives
    resonantly!
  • Use flexible substrate for scavenging energy
    produced by acoustic waves, ultrasonic waves, or
    hydraulic pressure/force or environment etc. for
    applications such as implantable biomedical
    devices, wireless sensors, and portable
    electronics
  • Continued work published as Direct-Current Nano
    generator Driven by Ultrasonic Waves Science 6
    April 2007Vol. 316. no. 5821, pp. 102 105
  • Nanogenerator is featured in the overview section
    in the NSF FY 2008 budget request to congress
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