Processes which lend materials new characteristics are generally complicated and therefore often rather difficult to reproduce. So surprise turns to astonishment when scientists report on new methods which not only produce outstanding results despite the fact that they use economically priced starting materials but also do not need expensive instrumentation.
Just a simple framework made of polystyrene
This is exactly what Jamil Elias and Laetitia Philippe of Empa's Mechanics of Materials and Nanostructures Laboratory in Thun have succeeded in doing. They used polystyrene spheres as a sort of scaffolding to create three-dimensional nanostructures of semiconducting zinc oxide on various substrates. The two scientists are convinced that the (nanostructured) «rough» but regularly-structured surfaces they have produced this way can be exploited in a range of electronic and optoelectronic devices such as solar cells and also short wave lasers, light emitting diodes and field emission displays.
The scientific world reacted promptly. The paper in which the results were reported was published in January 2010 in the on line edition of «Advanced Materials». In the same month it became the most frequently downloaded article, and in April it was selected to appear on the Inside Front Cover of the journal.
The principle behind the process is quite simple. Little spheres of polystyrene a few micrometers in diameter are placed on an electrically conducting surface where they orient themselves in regular patterns. Polystyrene is cheap and ubiquitous – it is widely used as a packaging material (for example for plastic yoghurt pots) or as insulating material in expanded form as a solidified foam.
Hollow bodies with prickles for photovoltaic applications
The tiny balls of polystyrene anchored in this way form the template on which the nanowires are desposited. Jamil Elias has succeeded in using an electrochemical method which himself has developed to vary the conductivity and electrolytic properties of the polystyrene balls in such way that the zinc oxide is deposited on the surface of the microspheres. Over time regular nanowires grow from this surface, and when this process is complete the polystyrene is removed, leaving behind hollow spherical structures with spines – little sea-urchins, as it were! Tightly packed on the underlying substrate, the sea-urchins lend it a three-dimensional structure, thereby increasing considerably its surface area.
This nanostructured surface is predestined for use in photovoltaic applications. The researchers expect that it will have excellent light scattering properties. This means the surface will be able to absorb significantly more sunlight and therefore be able to convert radiated energy into electricity more efficiently. In a project supported by the Swiss Federal Office of Energy (SFOE), Laetitia Philippe and her research team are developing extremely thin absorbers (ETAs) for solar cells, based these zinc oxide nanostructures.
Literature reference: J. Elias, C. Lévy-Clément, M. Bechelany, J. Michler, G.-Y. Wang, Z. Wang, L. Philippe: Hollow Urchin – like ZnO thin Films by Electrochemical Deposition, Advanced Materials, Volume 22, Issue 14, Pages 1607 – 1612 (April 12, 2010) http://www3.interscience.wiley.com/journal/123240975/abstract DOI: 10.1002/adma.200903098
Dr. Jamil Elias | EurekAlert!
Strange but true: Turning a material upside down can sometimes make it softer
20.10.2017 | Universitat Autonoma de Barcelona
Metallic nanoparticles will help to determine the percentage of volatile compounds
20.10.2017 | Lomonosov Moscow State University
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
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...
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...
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...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
20.10.2017 | Information Technology
20.10.2017 | Materials Sciences
20.10.2017 | Interdisciplinary Research