Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Digging sensors out of an efficiency hole


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:

More articles from Materials Sciences:

nachricht Custom sequences for polymers using visible light
22.03.2018 | Tokyo Metropolitan University

nachricht The search for dark matter widens
21.03.2018 | American Institute of Physics

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

Modular safety concept increases flexibility in plant conversion

22.03.2018 | Trade Fair News

New interactive map shows climate change everywhere in world

22.03.2018 | Earth Sciences

New technologies and computing power to help strengthen population data

22.03.2018 | Earth Sciences

Science & Research
Overview of more VideoLinks >>>