Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Zinc Oxide Materials Tapped for Tiny Energy Harvesting Devices

14.01.2015

New research helps pave the way toward highly energy-efficient zinc oxide-based micro energy harvesting devices with applications in portable communications, healthcare and environmental monitoring, and more.

Today, we’re surrounded by a variety of electronic devices that are moving increasingly closer to us – we can attach and wear them, or even implant electronics inside our bodies.


Giwan Yoon/Korea Advanced Institute of Science and Technology

This illustration shows stacked flexible nanogenerators (left), and a cross-sectional transmission electron microscopy image of the ZnO/AlN-stacked structure. The scale bar on the right represents 200 nm.

Many types of smart devices are readily available and convenient to use. The goal now is to make wearable electronics that are flexible, sustainable and powered by ambient renewable energy.

This last goal inspired a group of Korea Advanced Institute of Science and Technology (KAIST) researchers to explore how the attractive physical features of zinc oxide (ZnO) materials could be more effectively used to tap into abundant mechanical energy sources to power micro devices. They discovered that inserting aluminum nitride insulating layers into ZnO-based energy harvesting devices led to a significant improvement of the devices’ performance. The researchers report their findings in the journal Applied Physics Letters, from AIP Publishing.

“Mechanical energy exists everywhere, all the time, and in a variety of forms – including movement, sound and vibration. The conversion from mechanical energy to electrical energy is a reliable approach to obtain electricity for powering the sustainable, wireless and flexible devices – free of environmental limitations,” explained Giwan Yoon, a professor in the Department of Electrical Engineering at KAIST.

Piezoelectric materials such as ZnO, as well as several others, have the ability to convert mechanical energy to electrical energy, and vice versa. “ZnO nanostructures are particularly suitable as nanogenerator functional elements, thanks to their numerous virtues including transparency, lead-free biocompatibility, nanostructural formability, chemical stability, and coupled piezoelectric and semiconductor properties,” noted Yoon.

The key concept behind the group’s work? Flexible ZnO-based micro energy harvesting devices, aka “nanogenerators,” can essentially be comprised of piezoelectric ZnO nanorod or nanowire arrays sandwiched between two electrodes formed on the flexible substrates. In brief, the working mechanisms involved can be explained as a transient flow of electrons driven by the piezoelectric potential.

“When flexible devices can be easily mechanically deformed by various external excitations, strained ZnO nanorods or nanowires tend to generate polarized charges, which, in turn, generate piezoelectronic fields,” said Yoon. “This allows charges to accumulate on electrodes and it generates an external current flow, which leads to electronic signals. Either we can use the electrical output signals directly or store them in energy storage devices.”

Other researchers have reported that the use of insulating materials can help provide an extremely large potential barrier. “This makes it critically important that insulating materials are carefully selected and designed – taking both the material properties and the device operation mechanism into consideration,” said Eunju Lee, a postdoctoral researcher in Yoon’s group.

To date, however, there have been few efforts made to develop new insulating materials and assess their applicability to nanogenerator devices or determine their effects on the device output performance.

The KAIST researchers proposed, for the first time, new piezoelectric ZnO/aluminum nitride (AlN) stacked layers for use in nanogenerators.

“We discovered that inserting AlN insulating layers into ZnO-based harvesting devices led to a significant improvement of their performance – regardless of the layer thickness and/or layer position in the devices,” said Lee. “Also, the output voltage performance and polarity seem to depend on the relative position and thickness of the stacked ZnO and AlN layers, but this needs to be explored further.”

The group’s findings are expected to provide an effective approach for realizing highly energy-efficient ZnO-based micro energy harvesting devices. “This is particularly useful for self-powered electronic systems that require both ubiquity and sustainability – portable communication devices, healthcare monitoring devices, environmental monitoring devices and implantable medical devices,” pointed out Yoon. And there are potentially many other applications.

Next up, Yoon and colleagues plan to pursue a more in-depth study to gain a much more precise and comprehensive understanding of device operation mechanisms. “We’ll also explore the optimum device configurations and dimensions based on the operation mechanism analysis work,” he added.

The article, "Characteristics of piezoelectric ZnO/AlN—stacked flexible nanogenerators for energy harvesting applications," is authored by Eunju Lee, Jaedon Park, Munhyuk Yim, Yeongseon Kim and Giwan Yoon. It will be published in the journal Applied Physics Letters on January 13, 2015 (DOI: 10.1063/1.4904270). After that date, it can be accessed at: http://scitation.aip.org/content/aip/journal/apl/106/2/10.1063/1.4904270

The authors of this paper are affiliated with Korea Advanced Institute of Science and Technology.

ABOUT THE JOURNAL

Applied Physics Letters features concise, rapid reports on significant new findings in applied physics. The journal covers new experimental and theoretical research on applications of physics phenomena related to all branches of science, engineering, and modern technology. See: http://apl.aip.org 

Contact Information
Jason Socrates Bardi
American Institute of Physics
jbardi@aip.org
240-535-4954
@jasonbardi

Jason Socrates Bardi | newswise

More articles from Materials Sciences:

nachricht Spin current detection in quantum materials unlocks potential for alternative electronics
16.10.2017 | DOE/Oak Ridge National Laboratory

nachricht Missing atoms in a forgotten crystal bring luminescence
11.10.2017 | King Abdullah University of Science & Technology (KAUST)

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

Im Focus: New nanomaterial can extract hydrogen fuel from seawater

Hybrid material converts more sunlight and can weather seawater's harsh conditions

It's possible to produce hydrogen to power fuel cells by extracting the gas from seawater, but the electricity required to do it makes the process costly. UCF...

Im Focus: Small collisions make big impact on Mercury's thin atmosphere

Mercury, our smallest planetary neighbor, has very little to call an atmosphere, but it does have a strange weather pattern: morning micro-meteor showers.

Recent modeling along with previously published results from NASA's MESSENGER spacecraft -- short for Mercury Surface, Space Environment, Geochemistry and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

Conference Week RRR2017 on Renewable Resources from Wet and Rewetted Peatlands

28.09.2017 | Event News

 
Latest News

A single photon reveals quantum entanglement of 16 million atoms

16.10.2017 | Physics and Astronomy

The melting ice makes the sea around Greenland less saline

16.10.2017 | Earth Sciences

On the generation of solar spicules and Alfvenic waves

16.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>