Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

‘Nanospears’ Could Lead to Better Solar Cells, Lasers, Lighting

13.08.2009
Growing – and precisely aligning – microscopic, spear-shaped zinc oxide crystals on a surface of single-crystal silicon, researchers at Missouri University of Science and Technology may have developed a method to make more efficient solar cells.

Dr. Jay A. Switzer and his colleagues at Missouri S&T report in the journal Chemistry of Materials that their simple, inexpensive process could also lead to new materials for ultraviolet lasers, solid-state lighting and piezoelectric devices.

“It’s kind of like growing rock candy crystals on a string,” says Switzer, the Donald L. Castleman/Foundation for Chemical Research Professor of Discovery at Missouri S&T. But instead of using sugar water and string, Switzer’s team grows the zinc oxide “nanospears” on the single-crystal silicon placed in a beaker filled with an alkaline solution saturated with zinc ions. The process yields tilted, single-crystal, spear-shaped rods that grow out of the silicon surface, like tiny spikes.

The spears are about 100-200 nanometers in diameter – hundreds of times smaller than the width of a human hair – and about 1 micrometer in length. A nanometer – visible only with the aid of a high-power electron microscope – is one billionth of a meter, and some nanomaterials are only a few atoms in size.

The research is reported today (Tuesday, Aug. 11) in the journal’s online ASAP (“as soon as publishable”) section and will appear in an upcoming issue. The complete article, titled “Tilted Epitaxial ZnO Nanospears on Si(001) by Chemical Bath Deposition,” is available on the ASAP website at http://pubs.acs.org/doi/abs/10.1021/cm9010019.

Zinc oxide is a semiconductor that possesses some unusual physical properties, Switzer says. The material both absorbs and emits light, so it could be used in solar cells to absorb sunshine as well as in lasers or solid-state lighting as an emitter of light.

Silicon is also a semiconductor, but it absorbs light at a different part of the spectrum than zinc oxide. By growing zinc oxide on top of the silicon, “you’re putting two semiconductors on top of each other,” thereby widening the spectrum from which a solar cell could draw light, Switzer says.

“You can absorb more light and possibly get more power out” with a zinc oxide-silicon solar cell, he says.

Previous efforts to grow zinc oxide on silicon have been limited to expensive ultra-high-vacuum methods, and because of silicon’s high reactivity, it’s been impossible to deposit the zinc oxide directly, without the use of a third material as a buffer. In addition, previous attempts to align the two materials epitaxially – or perfectly one on top of the other – have been unsuccessful until now. By tilting the nanospears 51 degrees, Switzer and his team have reduced the mismatch from 40 percent to just 0.2 percent, a near-perfect alignment.

Epitaxially aligning the zinc oxide and silicon is important to ensure higher efficiency, Switzer says.

Switzer’s research is supported through a four-year, $700,000 grant from the Department of Energy’s Office of Basic Energy Sciences, Materials Sciences and Engineering Division.

Switzer’s co-authors for the Chemistry of Materials paper are Guojun Mu and Rakesh V. Gudavarthy, both graduate students in the Chemistry Department at Missouri S&T, and Dr. Elizabeth A. Kulp, a postdoctoral associate at Missouri S&T.

Andrew Careaga | Newswise Science News
Further information:
http://www.mst.edu

More articles from Power and Electrical Engineering:

nachricht Did you know that infrared heat and UV light contribute to the success of your barbecue?
26.07.2017 | Heraeus Noblelight GmbH

nachricht Ultrathin device harvests electricity from human motion
24.07.2017 | Vanderbilt University

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

CCNY physicists master unexplored electron property

26.07.2017 | Physics and Astronomy

Molecular microscopy illuminates molecular motor motion

26.07.2017 | Life Sciences

Large-Mouthed Fish Was Top Predator After Mass Extinction

26.07.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>