Ultrathin layers made of Tungsten and Selenium have been created at the Vienna University of Technology; experiments show that they may be used as flexible, semi-transparent solar cells
It does not get any thinner than this: The novel material graphene consists of only one atomic layer of carbon atoms and exhibits very special electronic properties. As it turns out, there are other materials too, which can open up intriguing new technological possibilities if they are arranged in just one or very few atomic layers. Researchers at the Vienna University of Technology have now succeeded for the first time in creating a diode made of tungsten diselenide. Experiments show that this material may be used to create ultrathin flexible solar cells. Even flexible displays could become possible.
Thin Layers are Different
At least since the Nobel Prize in physics was awarded in 2010 for creating graphene, the "two dimensional crystals" made of carbon atoms have been regarded as one of the most promising materials in electronics. In 2013, graphene research was chosen by the EU as a flagship-project, with a funding of one billion euros. Graphene can sustain extreme mechanical strain and it has great opto-electronic properties. With graphene as a light detector, optical signals can be transformed into electric pulses on extremely short timescales.
For one very similar application, however, graphene is not well suited for building solar cells. "The electronic states in graphene are not very practical for creating photovoltaics", says Thomas Mueller. Therefore, he and his team started to look for other materials, which, similarly to graphene, can arranged in ultrathin layers, but have even better electronic properties.
The material of choice was tungsten diselenide: It consists of one layer of tungsten atoms, which are connected by selenium atoms above and below the tungsten plane. The material absorbs light, much like graphene, but in tungsten diselenide, this light can be used to create electrical power.
The World's Thinnest Solar Cells
The layer is so thin that 95% of the light just passes through – but a tenth of the remaining five percent, which are absorbed by the material, are converted into electrical power. Therefore, the internal efficiency is quite high. A larger portion of the incident light can be used if several of the ultrathin layers are stacked on top of each other – but sometimes the high transparency can be a useful side effect. "We are envisioning solar cell layers on glass facades, which let part of the light into the building while at the same time creating electricity", says Thomas Mueller.
Today, standard solar cells are mostly made of silicon, they are rather bulky and inflexible. Organic materials are also used for opto-electronic applications, but they age rather quickly. "A big advantage of two-dimensional structures of single atomic layers is their crystallinity. Crystal structures lend stability", says Thomas Mueller.
The results of the experiments at the Vienna University of Technology have now been published in the journal "Nature Nanotechnology". The research field is extremely competitive: in the same issue of the journal, two more papers are published, in which very similar results are shown. Researchers at the MIT (Cambridge, USA) and at the University of Washington (Seattle, USA) have also discovered the great advantages of tungsten diselenide. There seems to be little doubt that this material will soon play an important role in materials science all over the world, much like graphene has in the last couple of years.
Prof. Thomas Müller
Vienna University of Technology
Gusshausstraße 27-29, 1040 Vienna
Florian Aigner | EurekAlert!
New concept for structural colors
18.05.2018 | Technische Universität Hamburg-Harburg
Saarbrücken mathematicians study the cooling of heavy plate from Dillingen
17.05.2018 | Universität des Saarlandes
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology