Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Digging sensors out of an efficiency hole

19.09.2017

The key to ultrathin high-efficiency sensors and solar cells could be materials covered with tiny trenches.

Future ultrathin solar cells and light sources could have their surfaces covered by tiny trenches, after A*STAR researchers found such structures enhance efficiency by four orders of magnitude.


A*STAR researchers find tiny trenches patterned into a gold surface enhance photoluminescence efficiency. Reproduced from Ref. 1 and licensed under CC BY 4.0 © 2016 Z. Wang et al.

Joel Yang from the A*STAR Institute of Materials Research and Engineering was part of an international collaboration that achieved a 20,000-fold increase in the photoluminescence of a one atom-thick layer of tungsten diselenide, by mounting it on a gold surface patterned with narrow trenches [1].

Tungsten diselenide is promising for ultra-sensitive, ultra-thin light sensors, solar cells and light-emitting diodes, because of its ability to absorb light and re-emit at a different frequency. However this effect only occurs for a single atom layer, so its efficiency is very low – most of the light passes straight through.

Yang’s inspiration was to mount the layer on a gold surface and trap the light energy at the interface of the two layers in the form of surface plasmons. To enhance the absorption of light, they added trenches to the gold layer under the tungsten diselenide.

“It was very surprising that such a large enhancement could be possible,” says Yang.

The key was matching the trench size to the energy so that the plasmons were trapped in the trenches through a resonant process known as the Purcell effect.

The team shone 633-nanometer light onto the sample and measured the output at 750 nanometers. They found 12 nm wide trenches in a grid pattern with spacing 200 nanometers gave the highest photoluminescence – 20,000 times more than a bare layer of tungsten diselenide.

To create the structure, the team etched a very flat silicon crystal to create a grid of ridges. Next they deposited a layer of gold onto the silicon and then peeled it off to reveal trenches where the ridges had been.

“The narrowness of the trenches and the flatness of the metal film is important,” Yang says. “Any roughness will interact detrimentally with the two-dimensional material.”

The gold was immersed in water and a film of tungsten diselenide floated on the water’s surface. The gold was then slowly raised out of the solution, emerging with the thin layer on top.

The simple structure has many advantages, says Yang. “The entire surface is exposed to the user, which makes it easy for further research, such as functionalizing the surface with chemicals or adding electrodes”.

It is also easier to manufacture than other plasmonic devices, which require a second layer above the thin layer, creating a sandwich.

The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering.

Associated links

Press release from A*STAR
Research paper

Journal information

Wang, Z., Dong, Z., Gu, Y., Chang, Y. H., Zhang, L., Li, L. J., et al. Giant photoluminescence enhancement in tungsten-diselenide–gold plasmonic hybrid structures. Nature Communications 7, 11283 (2016).

A*STAR Research | asia-Research News
Further information:
http://www.researchsea.com/html/article.php/aid/11072/cid/2/research/technology/the_agency_for_science__technology_and_research__a_star_/digging_sensors_out_of_an_efficiency_hole___.html

More articles from Materials Sciences:

nachricht Strange but true: Turning a material upside down can sometimes make it softer
20.10.2017 | Universitat Autonoma de Barcelona

nachricht Metallic nanoparticles will help to determine the percentage of volatile compounds
20.10.2017 | Lomonosov Moscow State University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

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...

Im Focus: Breaking: the first light from two neutron stars merging

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....

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...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | 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

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>