Bottles, packaging, furniture, car parts... all made of plastic. Today we find it difficult to imagine our lives without this key material that revolutionized technology over the last century.
There is wide-spread optimism in the scientific community that graphene will provide similar paradigm shifting advances in the decades to come. Mobile phones that fold, transparent and flexible solar panels, extra thin computers... the list of potential applications is endless. Scientists, industries and the European Commission are so convinced of the potential of graphene to revolutionize the world economy that they promise an injection of €1.000 million in graphene research.
The most recent discovery published in Nature Physics and made by researchers at the Institute of Photonic Science (ICFO), in collaboration with Massachusetts Institute of Technology, USA, Max Planck Institute for Polymer Research, Germany, and Graphenea S.L. Donostia-San Sebastian, Spain, demonstrate that graphene is able to convert a single photon that it absorbs into multiple electrons that could drive electric current (excited electrons) – a very promising discovery that makes graphene an important alternative material for light detection and harvesting technologies, now based on conventional semiconductors like silicon.
"In most materials, one absorbed photon generates one electron, but in the case of graphene, we have seen that one absorbed photon is able to produce many excited electrons, and therefore generate larger electrical signals" explains Frank Koppens, group leader at ICFO. This feature makes graphene an ideal building block for any device that relies on converting light into electricity. In particular, it enables efficient light detectors and potentially also solar cells that can harvest light energy from the full solar spectrum with lower loss.
The experiment consisted in sending a known number of photons with different energies (different colors) onto a monolayer of graphene. "We have seen that high energy photons (e.g. violet) are converted into a larger number of excited electrons than low energy photons (e.g. infrared). The observed relation between the photon energy and the number of generated excited electrons shows that graphene converts light into electricity with very high efficiency. Even though it was already speculated that graphene holds potential for light-to-electricity conversion, it now turns out that it is even more suitable than expected!" explains Tielrooij, researcher at ICFO.
Although there are some issues for direct applications, such as graphene's low absorption, graphene holds the potential to cause radical changes in many technologies that are currently based on conventional semiconductors. "It was known that graphene is able to absorb a very large spectrum of light colors. However now we know that once the material has absorbed light, the energy conversion efficiency is very high. Our next challenge will be to find ways of extracting the electrical current and enhance the absorption of graphene. Then we will be able to design graphene devices that detect light more efficiently and could potentially even lead to more efficient solar cells." concludes Koppens.
"Photoexcitation cascade and multiple hot-carrier generation in graphene". K.J. Tielrooij, J.C.W. Song, S.A. Jensen, A. Centeno, A. Pesquera, A. Zurutuza Elorza, M. Bonn, L.S. Levitov and F.H.L. Koppens.
ICFO-The Institute of Photonic Sciences was created in 2002 by the government of Catalonia and the Technical University of Catalonia - Barcelona Tech. ICFO is a center of research excellence devoted to the sciences and technologies of light with a triple mission: to conduct frontier research, train the next generation of scientists and technologists, and provide knowledge and technology transfer.
Research at ICFO targets the forefront of science and technology based on light with programs directed at applications in Health, Renewable Energies, Information Technologies, Security and Industrial processes, among others. The center currently hosts more than 250 researchers and PhD students working in more than 60 different laboratories. All research groups and facilities are located in a dedicated 14.000 m2 building situated in the Mediterranean Technology Park in the metropolitan area of Barcelona.
ICFO participates in a large number of projects and international networks of excellence and is host to the NEST program which is financed by Fundación Privada Cellex Barcelona. Groundbreaking research in graphene is being carried out at ICFO and through key collaborative research partnerships such as the FET Graphene Flagship. NEST Fellow Prof. Frank Koppens is the co-leader of the Optoelectonics work package within Flagship program.
Frank Koppens' Group: http://koppensgroup.icfo.es/
Graphene at ICFO: http://www.icfo.eu/graphene/index.htm
Brook Hardwick | Source: EurekAlert!
Further information: www.icfo.es
More articles from Materials Sciences:
Stacking 2-D materials produces surprising results
17.05.2013 | Massachusetts Institute of Technology
Engineered biomaterial could improve success of medical implants
15.05.2013 | University of Washington
Researchers have shown that, by using global positioning systems (GPS) to measure ground deformation caused by a large underwater earthquake, they can provide accurate warning of the resulting tsunami in just a few minutes after the earthquake onset.
For the devastating Japan 2011 event, the team reveals that the analysis of the GPS data and issue of a detailed tsunami alert would have taken no more than three minutes. The results are published on 17 May in Natural Hazards and Earth System Sciences, an open access journal of ...
A new study of glaciers worldwide using observations from two NASA satellites has helped resolve differences in estimates of how fast glaciers are disappearing and contributing to sea level rise.
The new research found glaciers outside of the Greenland and Antarctic ice sheets, repositories of 1 percent of all land ice, lost an average of 571 trillion pounds (259 trillion kilograms) of mass every year during the six-year study period, making the oceans rise 0.03 inches (0.7 mm) per year. ...
About 99% of the world’s land ice is stored in the huge ice sheets of Antarctica and Greenland, while only 1% is contained in glaciers.
However, the meltwater of glaciers contributed almost as much to the rise in sea level in the period 2003 to 2009 as the two ice sheets: about one third. This is one of the results of an international study with the involvement of geographers from the University of Zurich.
Second sound is a quantum mechanical phenomenon, which has been observed only in superfluid helium.
Physicists from the University of Innsbruck, Austria, in collaboration with colleagues from the University of Trento, Italy, have now proven the propagation of such a temperature wave in a quantum gas. The scientists have published their historic findings in the journal Nature.
Below a critical temperature, certain fluids become superfluid ...
Researchers use synthetic silicate to stimulate stem cells into bone cells
In new research published online May 13, 2013 in Advanced Materials, researchers from Brigham and Women's Hospital (BWH) are the first to report that synthetic silicate nanoplatelets (also known as layered clay) can induce stem cells to become bone cells without the need of additional bone-inducing factors.
Synthetic silicates are made ...
17.05.2013 | Physics and Astronomy
17.05.2013 | Physics and Astronomy
17.05.2013 | Physics and Astronomy
17.05.2013 | Event News
15.05.2013 | Event News
08.05.2013 | Event News