News Article | August 22, 2016
Light can take many different forms. Even in our day-to-day life, sunlight is vastly different from fluorescent light. In physics, when studying interactions between light and tiny particles, the shape of the light can make a big difference. Scientists from Okinawa Institute of Science and Technology Graduate University (OIST) and collaborators at the University of Innsbruck in Austria found that the interactions between particles trapped in light distributed along an optical microfiber, as well as the speed of particle movement were different based on the light's characteristics. The results were recently published in Scientific Reports.
News Article | April 12, 2016
Queen and worker ants develop from the same sets of genes, but perform completely different ecological roles. How the same genes result in two types of individuals is an ongoing mystery. In the past, scientists have only studied a small number of ant species at a time to try to understand the nature of queen-worker differences. However, a team from the Okinawa Institute of Science and Technology Graduate University (OIST) in tandem with the University of Helsinki and other collaborators from around the world, recently looked at a large data set with 16 species that provides insight into the differences between queen and worker ants.
News Article | March 6, 2016
New research has proposed a design for a submerged marine turbine that could harness ocean currents as a potential renewable energy resource. Researchers from the Quantum Wave Microscopy Unit at Okinawa Institute of Science and Technology Graduate University (OIST) have published their proposition in the journal Renewable Energy. The researchers specifically proposed a submerged marine turbine that could harness the energy of the Kuroshio Current, a north-flowing ocean current on the west side of the North Pacific Ocean, up against Japan’s own east coast. The Kuroshio Current is similar to the more well-known Gulf Stream current that runs around the top side of the Atlantic Ocean, and could provide consistent electricity much like fossil fuels have done. The newly proposed design could see a submerged marine turbine operate in the middle layer of the Kuroshio Current, 100 metres below the surface, where the waters of the current flow steadily and relatively calmly, even during the violent storms and typhoons that make their home in the region. The design itself is more a hybrid of a kite and a wind turbine, and comprises a float, a counterweight, a nacelle to house the electricity generating components, and three blades. The turbine would be anchored to the seabed, while its position in the current would turn the blades, generating near-constant electricity. As the researchers note, though ocean currents are relatively slow — averaging only 1-1.5 m/s — water is over 800 times more dense than air, meaning that even slow ocean currents are comparable to strong winds — and with the added benefit of being constant in both direction and speed. Get CleanTechnica’s 1st (completely free) electric car report → “Electric Cars: What Early Adopters & First Followers Want.” Come attend CleanTechnica’s 1st “Cleantech Revolution Tour” event → in Berlin, Germany, April 9–10. Keep up to date with all the hottest cleantech news by subscribing to our (free) cleantech newsletter, or keep an eye on sector-specific news by getting our (also free) solar energy newsletter, electric vehicle newsletter, or wind energy newsletter.
News Article | March 6, 2016
New research has found that, contrary to popular belief, geographically separated wind farms are acting in surprisingly similar ways. A team of researchers, led by Professor Mahesh M. Bandi of the Okinawa Institute of Science and Technology Graduate University (OIST), published findings in the journal New Journal of Physics, revealing that, counter to what was previously thought, wind farms connected to the grid saw power outputs fluctuate in similar ways. “It’s generally assumed that geographically distributed wind farms are independent,” Bandi said. “In other words, the fluctuations in power output from one wind farm are different from that of another wind farm, say 50 km away.” However, the data that Bandi and his team analysed, based on Irish wind farms connected to the local grid, revealed that wind farms did not function separately to one another, but rather “became part of a larger geographic weather system that forces all the wind farms to have similar or correlated outputs for a time span of up to one day.” “If there is a medium that connects them, then one will observe that the two wind farms will fluctuate in a similar fashion,” Bandi continued. “This does not mean their outputs are exactly synchronized at every instant, but on average their outputs fluctuate very similar to each other. The average is important. That is what we mean by correlated.” The results of their analysis allowed the researchers to quantify two types of forecast error: a timescale error “that quantifies the timescales over which the forecast models fail to predict high frequency power fluctuations,” and a scaling error, “that establishes a difference in the self-similar scaling of fluctuations as observed for actual generated power vis à vis the power that was forecast to be generated.” If all of this seems a little vague, the full report is available for free to read on the New Journal of Physics website, and provides more context for the two errors that were the focus of the report. Get CleanTechnica’s 1st (completely free) electric car report → “Electric Cars: What Early Adopters & First Followers Want.” Come attend CleanTechnica’s 1st “Cleantech Revolution Tour” event → in Berlin, Germany, April 9–10. Keep up to date with all the hottest cleantech news by subscribing to our (free) cleantech newsletter, or keep an eye on sector-specific news by getting our (also free) solar energy newsletter, electric vehicle newsletter, or wind energy newsletter.
Home > Press > Visualizing atoms of perovskite crystals: OIST researchers conduct the first atomic resolution study of perovskites used in next generation solar cells Abstract: Organic-inorganic perovskite materials are key components of the new generation of solar cells. Understanding properties of these materials is important for improving lifetime and quality of solar cells. Researchers from the Energy Materials and Surface Sciences (EMSS) Unit, led by Prof. Yabing Qi, at the Okinawa Institute of Science and Technology Graduate University (OIST) in collaboration with Prof. Youyong Li's group from Soochow University (China) and Prof. Nam-Gyu Park's group from Sungkyunkwan University (Korea) report in the Journal of the American Chemical Society the first atomic resolution study of organic-inorganic perovskite. Perovskites are a class of materials with the general chemical formula ABX3. A and B are positive ions bound by negative ions X. Organic-inorganic perovskites used in solar cells are usually methylammonium lead halides (CH3NH3PbX3, where X is bromine, iodine, or chlorine). The OIST scientists used a single crystal of methylammonium lead bromide (CH3NH3PbBr3) to create topographic images of its surface with a scanning tunneling microscope. This microscope uses a conducting tip that moves across the surface in a manner very similar to a finger moving across a Braille sign. While the bumps in Braille signs are a few millimetres apart, the microscope detects bumps that are more than million times smaller -- atoms and molecules. This is achieved by the quantum tunneling effect -- the ability of an electron to pass through a barrier. The probability of an electron passing between the material surface and the tip depends on the distance between the two. The resulting atomic-resolution topographic images reveal positions and orientations of atoms and molecules, and also provide a detailed look at structural defects in the surface. "At room temperature atoms and molecules are quite mobile, so we decided to freeze the crystal to almost absolute zero (-269ºC) to get a good picture of its atomic structure," says Dr Robin Ohmann, a member of the EMSS Unit and the first author of the paper. The crystal was cut and studied in a vacuum to avoid contamination of the surface. Dr Ohmann's colleagues from Soochow University calculated atomic structures using principles of quantum physics and then compared them with scanning tunneling microscopy data. The researchers discovered that methylammonium molecules can rotate and that they favour specific orientations that lead to two types of surface structures with distinctly different properties. Apart from rotation, these molecules affect positions of neighbouring bromine ions, further altering the atomic structure. Since the structure dictates the electronic properties of the material, the geometric positions of atoms are essential for understanding of solar cells. Scanning tunneling microscope images also reveal local imperfections caused by dislocations of molecules and ions and, probably, missing atoms. These imperfections may affect device performance, for example, by changing electrical properties such as conductivity. The structure of perovskite materials is temperature-sensitive and the observed structure of the frozen crystal might not be fully identical to the structure at room temperature. However, the comprehensive description of perovskite crystals at the atomic level paves the way to better understanding of their behaviour under real-life conditions. The current findings shed light on molecule-ion interplay on the surface of an organic-inorganic crystal and should help to improve designs of future solar cells. The next goal of the researchers is to examine interactions between perovskites and other molecules, for example water molecules that are known to interfere with the performance of solar cells. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.