Graphene Research and the World’s 5 Biggest Problems: From Clean Water and Healthcare to Energy and Infastructure – Solutions based in Graphene may Hold the Key

In September 2015, world leaders gathered at a historic UN summit to adopt the Sustainable Development Goals (SDGs). These are 17 ambitious targets and indicators that help guide and coordinate governments and international organizations to alleviate global problems. For example, SDG 3 is to “ensure healthy lives and promote well-being for all at all ages.” Others include access to clean water, reducing the effects of climate change, and affordable healthcare.

If you think these goals might be difficult to meet, you’re right. Reports show progress is lacking in many of the 17 categories, implying they may not be met by the target date of 2030. However, paired with progress in social and political arenas, advances in science and technology could be a key accelerant to progress too.

Just one example? Graphene, a futuristic material with a growing set of potential applications.

Graphene is comprised of tightly-knit carbon atoms arranged into a sheet only one atom thick. This makes it the thinnest substance ever made, yet it is 200 times stronger than steel, flexible, stretchable, self-healing, transparent, more conductive than copper, and even superconductive. A square meter of graphene weighing a mere 0.0077 grams can support four kilograms. It is a truly remarkable material—but this isn’t news to science and tech geeks.

Headlines touting graphene as the next wonder material have been a regular occurrence in the last decade, and the trip from promise to practicality has felt a bit lengthy.

But that’s not unexpected; it can take time for new materials to go mainstream. Meanwhile, the years researching graphene have yielded a long list of reasons to keep at it.

Since first isolated in 2004 at the University of Manchester—work that led to a Nobel Prize in 2010— researchers all over the world have been developing radical ways to use and, importantly, make graphene. Indeed, one of the primary factors holding back widespread adoption has been how to produce graphene at scale on the cheap, limiting it to the lab and a handful of commercial applications. Fortunately, there have been advances toward mass production.

Last year, for example, a team from Kansas State University used explosions to synthesize large quantities of graphene. Their method is simple: Fill a chamber with acetylene or ethylene gas and oxygen. Use a vehicle spark plug to create a contained detonation. Collect the graphene that forms afterward. Acetylene and ethylene are composed of carbon and hydrogen, and when the hydrogen is consumed in the explosion, the carbon is free to bond with itself, forming graphene. This method is efficient because all it takes is a single spark.

Whether this technique will usher in the graphene revolution, as some have claimed, remains to be seen. What’s more certain is there will be no shortage of problems solved when said revolution arrives. Here’s a look at the ways today’s research suggests graphene may help the UN meet its ambitious development goals.

Clean Water

SDG 6 is to “ensure availability and sustainable management of water and sanitation for all.” As of now, the UN estimates that “water scarcity affects more than 40 percent of the global population and is projected to rise.”

Graphene-based filters could very well be the solution. Jiro Abraham from the University of Manchester helped develop scalable graphene oxide sieves to filter seawater. He claims, “The developed membranes are not only useful for desalination, but the atomic scale tunability of the pore size also opens new opportunity to fabricate membranes with on-demand filtration capable of filtering out ions according to their sizes.”

Furthermore, researchers from Monash University and the University of Kentucky have developed graphene filters that can filter out anything larger than one nanometer. They say their filters “could be used to filter chemicals, viruses, or bacteria from a range of liquids. It could be used to purify water, dairy products or wine, or in the production of pharmaceuticals.”

Carbon Emissions

SDG 13 focuses on taking “urgent action to combat climate change and its impacts.”

Of course, one of the main culprits behind climate change is the excessive amount of carbon dioxide being emitted into the atmosphere. Graphene membranes have been developed that can capture these emissions.

Researchers at the University of South Carolina and Hanyang University in South Korea independently developed graphene-based filters that can be used to separate unwanted gases from industrial, commercial, and residential emissions. Henry Foley at the University of Missouri has claimed these discoveries are “something of a holy grail.”

With these, the world might be able to stem the rise of CO2 in the atmosphere, especially now that we have crossed the important 400 parts per million threshold.

Healthcare

Many around the world do not have access to adequate healthcare, but graphene may have an impact here as well.

First of all, graphene’s high mechanical strength makes it a perfect material for replacing body parts like bones, and because of its conductivity it can replace body parts that require electrical current, like organs and nerves. In fact, researchers at the Michigan Technological University are working on using 3D printers to print graphene-based nerves, and this team is developing biocompatible materials using graphene to conduct electricity.

Graphene can also be used to make biomedical sensors for detecting diseases, viruses, and other toxins. Because every atom of graphene is exposed, due to it being only one atom thick, sensors can be far more sensitive. Graphene oxide sensors, for example, could detect toxins at levels 10 times less than today’s sensors. These sensors could be placed on or under the skin and provide doctors and researchers with vast amounts of information.

Chinese scientists have even created a sensor that can detect a single cancerous cell. Further, scientists at the University of Manchester report graphene oxide can hunt and neutralize cancer stem cells.

Infrastructure

SDG 9 is to “build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation.” Graphene-enhanced composites and other building materials could bring us closer to meeting this goal.

Recent research shows that the more graphene is added, the better the composite becomes. This means graphene can be added to building materials like concrete, aluminum, etc., which will allow for stronger and lighter materials.

Resins are also getting better thanks to the addition of graphene. Research by Graphene Flagship, the EU’s billion-euro project to further graphene research, and their partner Avanzare suggests “graphene enhances the functionality of the resin, combining graphene’s electrical conductivity and mechanical strength with excellent corrosion resistance.” Some uses for this are making pipes and storage tanks corrosion-resistant, and making stronger adhesives.

Energy

SDG 7 is to “ensure access to affordable, reliable, sustainable and modern energy for all.” Because of its light weight, conductivity, and tensile strength, graphene may make sustainable energy cheaper and more efficient.

For example, graphene composites can be used to create more versatile solar panels. Researchers at MIT say, “The ability to use graphene…is making possible truly flexible, low-cost, transparent solar cells that can turn virtually any surface into a source of electric power.”

We’ll also be able to build bigger and lighter wind turbines thanks to graphene composites.

Further, graphene is already being used to enhance traditional lithium-ion batteries, which are the batteries commonly found in consumer electronics. Research is also being done into graphene aerogels for energy storage and supercapacitors. All of these will be essential for large-scale storage of renewable energy.

Over the next decade, graphene is likely to find more and more uses out in the real world, not only helping the UN and member states meet the SDGs, but enhancing everything from touch screens to MRI machines and from transistors to unknown uses as a superconductor.

New research is being published and new patents being filed regularly, so keep an eye out for this amazing material.

UC Berkeley Labs: A Semiconductor That Can Beat the Heat

Berkeley Lab, UC Berkeley scientists discover unique thermoelectric properties in cesium tin iodide

JULY 31, 2017

A newly discovered collective rattling effect in a type of crystalline semiconductor blocks most heat transfer while preserving high electrical conductivity – a rare pairing that scientists say could reduce heat buildup in electronic devices and turbine engines, among other possible applications.

A team led by scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) discovered these exotic traits in a class of materials known as halide perovskites, which are also considered promising candidates for next-generation solar panels, nanoscale lasers, electronic cooling, and electronic displays.

These interrelated thermal and electrical (or “thermoelectric”) properties were found in nanoscale wires of cesium tin iodide (CsSnI3). The material was observed to have one of the lowest levels of heat conductivity among materials with a continuous crystalline structure.

Image – Rattling structures of halide perovskites: cesium tin iodide (left) and cesium lead iodide (right). (Credit: Berkeley Lab/UC Berkeley)

This so-called single-crystal material can also be more easily produced in large quantities than typical thermoelectric materials, such as silicon-germanium, researchers said.

“Its properties originate from the crystal structure itself. It’s an atomic sort of phenomenon,” said Woochul Lee, a postdoctoral researcher at Berkeley Lab who was the lead author of the study, published the week of July 31 in the Proceedings of the National Academy of Sciences journal. These are the first published results relating to the thermoelectric performance of this single crystal material.

Researchers earlier thought that the material’s thermal properties were the product of “caged” atoms rattling around within the material’s crystalline structure, as had been observed in some other materials. Such rattling can serve to disrupt heat transfer in a material.

“We initially thought it was atoms of cesium, a heavy element, moving around in the material,” said Peidong Yang, a senior faculty scientist at Berkeley Lab’s Materials Sciences Division who led the study.

Jeffrey Grossman, a researcher at the Massachusetts Institute of Technology, then performed some theory work and computerized simulations that helped to explain what the team had observed. 

Researchers also used Berkeley Lab’s Molecular Foundry, which specializes in nanoscale research, in the study.

“We believe there is essentially a rattling mechanism, not just with the cesium. It’s the overall structure that’s rattling; it’s a collective rattling,” Yang said. “The rattling mechanism is associated with the crystal structure itself,” and is not the product of a collection of tiny crystal cages. “It is group atomic motion,” he added.

Within the material’s crystal structure, the distance between atoms is shrinking and growing in a collective way that prevents heat from easily flowing through.

But because the material is composed of an orderly, single-crystal structure, electrical current can still flow through it despite this collective rattling. Picture its electrical conductivity is like a submarine traveling smoothly in calm underwater currents, while its thermal conductivity is like a sailboat tossed about in heavy seas at the surface.

Yang said two major applications for thermoelectric materials are in cooling, and in converting heat into electrical current. For this particular cesium tin iodide material, cooling applications such as a coating to help cool electronic camera sensors may be easier to achieve than heat-to-electrical conversion, he said.

A challenge is that the material is highly reactive to air and water, so it requires a protective coating or encapsulation to function in a device.

Cesium tin iodide was first discovered as a semiconductor material decades ago, and only in recent years has it been rediscovered for its other unique traits, Yang said. “It turns out to be an amazing gold mine of physical properties,” he noted.

SEM images of suspended micro-island devices. Individual AIHP NW is suspended between two membranes. (Credit: Berkeley Lab/UC Berkeley)

To measure the thermal conductivity of the material, researchers bridged two islands of an anchoring material with a cesium tin iodide nanowire. The nanowire was connected at either end to micro-islands that functioned as both a heater and a thermometer. 
Researchers heated one of the islands and precisely measured how the nanowire transported heat to the other island.

They also performed scanning electron microscopy to precisely measure the dimensions of the nanowire. They used these dimensions to provide an exacting measure of the material’s thermal conductivity. The team repeated the experiment with several different nanowire materials and multiple nanowire samples to compare thermoelectric properties and verify the thermal conductivity measurements.

“A next step is to alloy this (cesium tin iodide) material,” Lee said. “This may improve the thermoelectric properties.”

Also, just as computer chip manufacturers implant a succession of elements into silicon wafers to improve their electronic properties – a process known as “doping” – scientists hope to use similar techniques to more fully exploit the thermoelectric traits of this semiconductor material. This is relatively unexplored territory for this class of materials, Yang said.

The research team also included other scientists from Berkeley Lab’s Materials Sciences Division and the Molecular Foundry, the Kavli Energy NanoScience Institute at UC Berkeley and Berkeley Lab, and UC Berkeley’s Department of Chemistry.

The Molecular Foundry is a DOE Office of Science User Facility that provides free access to state-of-the-art equipment and multidisciplinary expertise in nanoscale science to visiting scientists from all over the world.

This work was supported by the Department of Energy’s Office of Basic Energy Sciences.
More information about Peidong Yang’s research group: http://nanowires.berkeley.edu/.

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Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel Prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit http://www.lbl.gov.
DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

McMaster University: Researchers resolve problem holding back a Technology Revolution – Smaller, Nimbler Semiconductors that are expected to Replace Silicon – Carbon Nanotubes

 

Artistic rendition of a metallic carbon nanotube being pulled into solution, in analogy to the work described by the Adronov group. Credit: Alex Adronov, McMaster University

Imagine an electronic newspaper that you could roll up and spill your coffee on, even as it updated itself before your eyes.

It’s an example of the technological revolution that has been waiting to happen, except for one major problem that, until now, scientists have not been able to resolve.

Researchers at McMaster University have cleared that obstacle by developing a new way to purify carbon nanotubes – the smaller, nimbler semiconductors that are expected to replace silicon within computer chips and a wide array of electronics.

“Once we have a reliable source of pure nanotubes that are not very expensive, a lot can happen very quickly,” says Alex Adronov, a professor of Chemistry at McMaster whose research team has developed a new and potentially cost-efficient way to purify carbon nanotubes.

Carbon nanotubes – hair-like structures that are one billionth of a metre in diameter but thousands of times longer – are tiny, flexible conductive nano-scale materials, expected to revolutionize computers and electronics by replacing much larger silicon-based chips.

A major problem standing in the way of the new technology, however, has been untangling metallic and semiconducting carbon nanotubes, since both are created simultaneously in the process of producing the microscopic structures, which typically involves heating carbon-based gases to a point where mixed clusters of nanotubes form spontaneously as black soot.

Only pure semiconducting or metallic carbon nanotubes are effective in device applications, but efficiently isolating them has proven to be a challenging problem to overcome. Even when the nanotube soot is ground down, semiconducting and metallic nanotubes are knotted together within each grain of powder. Both components are valuable, but only when separated.

Researchers around the world have spent years trying to find effective and efficient ways to isolate carbon nanotubes and unleash their value.

While previous researchers had created polymers that could allow semiconducting carbon nanotubes to be dissolved and washed away, leaving metallic nanotubes behind, there was no such process for doing the opposite: dispersing the metallic nanotubes and leaving behind the semiconducting structures.

Now, Adronov’s research group has managed to reverse the electronic characteristics of a polymer known to disperse semiconducting nanotubes – while leaving the rest of the polymer’s structure intact. By so doing, they have reversed the process, leaving the semiconducting nanotubes behind while making it possible to disperse the metallic nanotubes.

The researchers worked closely with experts and equipment from McMaster’s Faculty of Engineering and the Canada Centre for Electron Microscopy, located on the university’s campus.

“There aren’t many places in the world where you can to this type of interdisciplinary work,” Adronov says.

The next step, he explains, is for his team or other researchers to exploit the discovery by finding a way to develop even more efficient polymers and scale up the process for commercial production.

The research is described in the cover story of Chemistry – A European Journal.

Explore further: Carbon nanotube ‘ink’ may lead to thinner, lighter transistors and solar cells

Journal reference:Chemistry – A European Journal

Provided by:McMaster University

 

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Stanford University: Flawed “nanodiamonds” could produce next-generation tools for imaging and communications

Close-up of purified diamondoids on a lab bench. Too small to see with the naked eye, diamondoids are visible only when they clump together in fine, sugar-like crystals like these.

 

Stanford and SLAC National Accelerator Laboratory jointly run the world’s leading program for isolating and studying diamondoids—the tiniest possible specks of diamond. Found naturally in petroleum fluids, these interlocking carbon cages weigh less than a billionth of a billionth of a carat (a carat weighs about the same as 12 grains of rice); the smallest ones contain just 10 atoms.

Over the past decade, a team led by two Stanford-SLAC faculty members—Nick Melosh, an associate professor of materials science and engineering and of photon science, and Zhi-Xun Shen, a professor of photon science and of physics and applied physics – has found potential roles for diamondoids in improving electron microscope images, assembling materials and printing circuits on computer chips. The team’s work takes place within SIMES, the Stanford Institute for Materials and Energy Sciences, which is run jointly with SLAC.

Before they can do that, though, just getting the diamondoids is a technical feat. It starts at the nearby Chevron refinery in Richmond, California, with a railroad tank car full of crude oil from the Gulf of Mexico. “We analyzed more than a thousand oils from around the world to see which had the highest concentrations of diamondoids,” says Jeremy Dahl, who developed key diamondoid isolation techniques with fellow Chevron researcher Robert Carlson before both came to Stanford—Dahl as a physical science research associate and Carlson as a visiting scientist.

Solutions containing diamondoids await purity analysis in a SLAC lab. Credit: Christopher Smith, SLAC National Accelerator Laboratory

The original isolation steps were carried out at the Chevron refinery, where the selected crudes were boiled in huge pots to concentrate the diamondoids. Some of the residue from that work came to a SLAC lab, where small batches are repeatedly boiled to evaporate and isolate molecules of specific weights. These fluids are then forced at high pressure through sophisticated filtration systems to separate out diamondoids of different sizes and shapes, each of which has different properties.

The diamondoids themselves are invisible to the eye; the only reason we can see them is that they clump together in fine, sugar-like crystals. “If you had a spoonful,” Dahl says, holding a few in his palm, “you could give 100 billion of them to every person on Earth and still have some left over.”

Recently, the team started using diamondoids to seed the growth of flawless, nano-sized diamonds in a lab at Stanford. By introducing other elements, such as silicon or nickel, during the growing process, they hope to make nanodiamonds with precisely tailored flaws that can produce single photons of light for next-generation optical communications and biological imaging.

Jeremy Dahl holds clumps of diamondoid crystals. Credit: Christopher Smith, SLAC National Accelerator Laboratory

Early results show that the quality of optical materials grown from diamondoid seeds is consistently high, says Stanford’s Jelena Vuckovic, a professor of electrical engineering who is leading this part of the research with Steven Chu, professor of physics and of molecular and cellular physiology.

“Developing a reliable way of growing the nanodiamonds is critical,” says Vuckovic, who is also a member of Stanford Bio-X. “And it’s really great to have that source and the grower right here at Stanford. Our collaborators grow the material, we characterize it and we give them feedback right away. They can change whatever we want them to change.”

Nano-scale diamondoid crystals, seen above, are derived from petroleum. They have potential for applications in energy, electronics, and molecular imaging. Credit: Nick Melosh

Explore further: Forces within molecules can strengthen extra-long carbon-carbon bonds

Provided by: Stanford University

 

Quantum Dots: Enhancing Light-to-Current Conversion: Better Semiconductors, Solar Cells and Photdetectors

Single nanocrystal spectroscopy identifies the interaction between zero-dimensional CdSe/ZnS nano crystals (quantum dots) and two-dimensional layered tin disulfide as a non-radiative energy transfer, whose strength increases with increasing …more

Harnessing the power of the sun and creating light-harvesting or light-sensing devices requires a material that both absorbs light efficiently and converts the energy to highly mobile electrical current. Finding the ideal mix of properties in a single material is a challenge, so scientists have been experimenting with ways to combine different materials to create “hybrids” with enhanced features.

In two just-published papers, scientists from the U.S. Department of Energy’s Brookhaven National Laboratory, Stony Brook University, and the University of Nebraska describe one such approach that combines the excellent light-harvesting properties of quantum dots with the tunable electrical conductivity of a layered tin disulfide semiconductor.

The hybrid material exhibited enhanced light-harvesting properties through the absorption of light by the quantum dots and their energy transfer to tin disulfide, both in laboratory tests and when incorporated into electronic devices. The research paves the way for using these materials in optoelectronic applications such as energy-harvesting photovoltaics, light sensors, and light emitting diodes (LEDs).

According to Mircea Cotlet, the physical chemist who led this work at Brookhaven Lab’s Center for Functional Nanomaterials (CFN), a DOE Office of Science User Facility, “Two-dimensional metal dichalcogenides like tin disulfide have some promising properties for solar energy conversion and photodetector applications, including a high surface-to-volume aspect ratio. But no semiconducting material has it all. These materials are very thin and they are poor light absorbers. So we were trying to mix them with other nanomaterials like light-absorbing quantum dots to improve their performance through energy transfer.”

One paper, just published in the journal ACS Nano, describes a fundamental study of the hybrid quantum dot/tin disulfide material by itself. The work analyzes how light excites the quantum dots (made of a cadmium selenide core surrounded by a zinc sulfide shell), which then transfer the absorbed energy to layers of nearby tin disulfide.

“We have come up with an interesting approach to discriminate energy transfer from charge transfer, two common types of interactions promoted by light in such hybrids,” said Prahlad Routh, a graduate student from Stony Brook University working with Cotlet and co-first author of the ACS Nano paper. “We do this using single nanocrystal spectroscopy to look at how individual quantum dots blink when interacting with sheet-like tin disulfide. This straightforward method can assess whether components in such semiconducting hybrids interact either by energy or by charge transfer.”

The researchers found that the rate for non-radiative energy transfer from individual quantum dots to tin disulfide increases with an increasing number of tin disulfide layers. But performance in laboratory tests isn’t enough to prove the merits of potential new materials. So the scientists incorporated the hybrid material into an electronic device, a photo-field-effect-transistor, a type of photon detector commonly used for light sensing applications.

As described in a paper published online March 24 in Applied Physics Letters, the hybrid material dramatically enhanced the performance of the photo-field-effect transistors-resulting in a photocurrent response (conversion of light to electric current) that was 500 percent better than transistors made with the tin disulfide material alone.

“This kind of energy transfer is a key process that enables photosynthesis in nature,” said Chang-Yong Nam, a materials scientist at Center for Functional Nanomaterials and co-corresponding author of the APL paper. “Researchers have been trying to emulate this principle in light-harvesting electrical devices, but it has been difficult particularly for new material systems such as the tin disulfide we studied. Our device demonstrates the performance benefits realized by using both energy transfer processes and new low-dimensional materials.”

Cotlet concludes, “The idea of ‘doping’ two-dimensional layered materials with quantum dots to enhance their light absorbing properties shows promise for designing better solar cells and photodetectors.”

Explore further: Small size enhances charge transfer in quantum dots

More information: Yuan Huang et al. Hybrid quantum dot-tin disulfide field-effect transistors with improved photocurrent and spectral responsivity, Applied Physics Letters (2016). DOI: 10.1063/1.4944781

Huidong Zang et al. Nonradiative Energy Transfer from Individual CdSe/ZnS Quantum Dots to Single-Layer and Few-Layer Tin Disulfide, ACS Nano (2016). DOI: 10.1021/acsnano.6b01538

Journal reference: ACS Nano Applied Physics Letters

MIT: New Institute Creates Accelerated Innovations in Nano Enabled Fibers and Fabrics

Professor Yoel Fink, director of MIT’s Research Laboratory of Electronics

Photo: M. Scott Brauer

National public-private consortium led by MIT will involve manufacturers, universities, agencies, companies.

A wide range of industries are expected to benefit from these revolutionary fibers and textiles, including apparel, consumer products, automotive, medical devices, and consumer electronics. “Fibers and fabrics are ubiquitous,” Fink says. “Our institute will go everywhere a fiber and fabric goes.”

An independent nonprofit founded by MIT has been selected to run a new, $317 million public-private partnership announced today by Secretary of Defense Ashton Carter.

The partnership, named the Advanced Functional Fibers of America (AFFOA) Institute, has won a national competition for federal funding to create the latest Manufacturing Innovation Institute. It is designed to accelerate innovation in high-tech, U.S.-based manufacturing involving fibers and textiles.

The proposal for the institute was led by Professor Yoel Fink, director of MIT’s Research Laboratory of Electronics (RLE). The partnership includes 32 universities, 16 industry members, 72 manufacturing entities, and 26 startup incubators, spread across 27 states and Puerto Rico.

This is the eighth Manufacturing Innovation Institute established to date, and the first to be headquartered in New England. The headquarters will be established in Cambridge, Massachusetts, in proximity to the MIT campus and its U.S. Army-funded Institute for Soldier Nanotechnology, as well as the Natick Soldier Research Development and Engineering Center.

This unique partnership, Fink says, has the potential to create a whole new industry, based on breakthroughs in fiber materials and manufacturing. These new fibers and the fabrics made from them will have the ability to see, hear, and sense their surroundings; communicate; store and convert energy; monitor health; control temperature; and change their color.

The new initiative will receive $75 million in federal funding out of a total of $317 million through cost sharing among the Department of Defense, industrial partners, venture capitalists, universities, nonprofits, and states including the Commonwealth of Massachusetts. The initial funding will cover a five-year period and will be administered through the new, independent, nonprofit organization set up for the purpose. The partnership, which will focus on both developing new technologies and training the workforce needed to operate and maintain these production systems, also includes a network of community colleges and experts in career and technical education for manufacturing.

“Massachusetts’s innovation ecosystem is reshaping the way that people interact with the world around them,” says Massachusetts Gov. Charlie Baker. “This manufacturing innovation institute will be the national leader in developing and commercializing textiles with extraordinary properties. It will extend to an exciting new field our ongoing efforts to nurture emerging industries, and grow them to scale in Massachusetts. And it will serve as a vital piece of innovation infrastructure, to support the development of the next generation of manufacturing technology, and the development of a highly skilled workforce.”

“Through this manufacturing innovation institute, Massachusetts researchers and Massachusetts employers will collaborate to unlock new advances in military technology, medical care, wearable technology, and fashion,” adds Massachusetts Lt. Gov. Karyn Polito. “This, in turn, will help drive business expansion, support the competitiveness of local manufacturers, and create new employment opportunities for residents across the Commonwealth.”

Announcing the new institute at an event at MIT, Carter stressed the importance of technology and innovation to the mission of the Department of Defense and to national security broadly: “The intersection of the two is truly an opportunity-rich environment. These issues matter. They have to do with our protection and our security, and creating a world where our fellow citizens can go to school and live their lives, and dream their dreams, and one day give their children a better future. Helping defend your country and making a better world is one of the noblest things that a business leader, a technologist, an entrepreneur, or a young person can do, and we’re all grateful to all of you for doing that with us.”

A new age of fabrics

For thousands of years, humans have used fabrics in much the same way, to provide basic warmth and aesthetics. Clothing represents “one of the most ancient forms of human expression,” Fink says, but one that is now, for the first time, poised to undergo a profound transformation — the dawn of a “fabric revolution.”

“What makes this point in time different? The answer is research,” Fink says: Objects that serve many complex functions are always made of multiple materials, whereas single-material objects, such as a drinking glass, usually have just a single, simple function. But now, new technology — some of it developed in Fink’s own laboratory — is changing all that, making it possible to integrate many materials and complex functional structures into a fabric’s very fibers, and to create fiber-based devices and functional fabric systems.

The semiconductor industry has shown how to combine millions of transistors into an integrated circuit that functions as a system; as described by “Moore’s law,” the number of devices and functions has doubled in computer chips every couple of years. Fink says the team envisions that the number of functions in a fiber will grow with similar speed, paving the way for highly functional fabrics.

The challenge now is to execute this vision, Fink says. While many textile and apparel companies and universities have figured out pieces of this puzzle, no single one has figured it all out.

“It turns out there is no company or university in the world that knows how to do all of this,” Fink says. “Instead of creating a single brick-and-mortar center, we set out to assemble and organize companies and universities that have manufacturing and ‘making’ capabilities into a network — a ‘distributed foundry’ capable of addressing the manufacturing challenges. To date, 72 manufacturing entities have signed up to be part of our network.”

“With a capable manufacturing network in place,” Fink adds, “the question becomes: How do we encourage and foster product innovation in this new area?” The answer, he says, lies at the core of AFFOA’s activities: Innovators across the country will be invited to execute “advanced fabric” products on prototyping and pilot scales. Moreover, the center will link these innovators with funding from large companies and venture capital investors, to execute their ideas through the manufacturing stage. The center will thus lower the barrier to innovation and unleash product creativity in this new domain, he says.

Promoting leadership in manufacturing

The federal selection process for the new institute was administered by the U.S. Department of Defense’s Manufacturing Technology Program and the U.S. Army’s Natick Soldier Research, Development and Engineering Center and Contracting Command in New Jersey. Retired Gen. Paul J. Kern will serve as chairman of the AFFOA Institute.

As explained in the original call for proposals to create this institute, the aim is to ensure “that America leads in the manufacturing of new products from leading edge innovations in fiber science, commercializing fibers and textiles with extraordinary properties. Known as technical textiles, these modern day fabrics and fibers boast novel properties ranging from being incredibly lightweight and flame resistant, to having exceptional strength. Technical textiles have wide-ranging applications, from advancing capabilities of protective gear allowing fire fighters to battle the hottest flames, to ensuring that a wounded soldier is effectively treated with an antimicrobial compression bandage and returned safely.”

In addition to Fink, the new partnership will include Tom Kochan, the George Maverick Bunker Professor of Management at MIT’s Sloan School of Management, who will serve as chief workforce officer coordinating the nationwide education and workforce development (EWD) plan. Pappalardo Professor of Mechanical Engineering Alexander Slocum will be the EWD deputy for education innovation. Other key MIT participants will include professors Krystyn Van Vliet from the Materials Science and Engineering and Biological Engineering departments; Peko Hosoi and Kripa Varanasi from the Department of Mechanical Engineering; and Gregory Rutledge from the Department of Chemical Engineering.

Among the industry partners who will be members of the partnership are companies such as Warwick Mills, DuPont, Steelcase, Nike, and Corning. Among the academic partners are Drexel University, the University of Massachusetts at Amherst, the University of Georgia, the University of Tennessee, and the University of Texas at Austin.

In a presentation last fall about the proposed partnership, MIT President L. Rafael Reif said, “We believe that partnerships — with industry and government and across academia — are critical to our capacity to create positive change.” He added, “Our nation has no shortage of smart, ambitious people with brilliant new ideas. But if we want a thriving economy, producing more and better jobs, we need more of those ideas to get to market faster.” Accelerating such implementation is at the heart of the new partnership’s goals.

Connecting skills, workers, and jobs

This partnership, Reif said, will be “a system that connects universities and colleges with motivated companies and with far-sighted government agencies, so we can learn from each other and work with each other. A system that connects workers with skills, and skilled workers with jobs. And a system that connects advanced technology ideas to the marketplace or to those who can get them to market.”

Part of the power of this new collaboration, Fink says, is combining the particular skills and resources of the different partners so that they “add up to something that’s more than the sum of the parts.” Existing large companies can contribute both funding and expertise, smaller startup companies can provide their creative new ideas, and the academic institutions can push the research boundaries to open up new technological possibilities.

“MIT recognizes that advancing manufacturing is vital to our innovation process, as we explored in our Production in the Innovation Economy (PIE) study,” says MIT Provost Martin Schmidt. “AFFOA will connect our campus even more closely with industries (large and small), with educational organizations that will develop the skilled workers, and with government at the state and federal level — all of whom are necessary to advance this new technology. AFFOA is an exciting example of the public-private partnerships that were envisioned in the recommendation of the Advanced Manufacturing Partnership.”

“Since MIT’s start, there has always been an emphasis on ‘mens et manus,’ using our minds and hands to make inventions useful at scales that impact the nation and the world,” adds Van Vliet, the director of manufacturing innovation for MIT’s Innovation Initiative, who has served as the faculty lead in coordinating MIT’s response to manufacturing initiatives that result from the Advanced Manufacturing Partnership. “What makes this new partnership very exciting is, this is for the first time a manufacturing institute headquartered in our region that connects our students and our faculty with local and national industrial partners, to really scale up production of many new fiber and textile technologies.”

“Participating in this group of visionaries from government, academia, and industry — who are all motivated by the goal of advancing a new model of American textile manufacturing and helping to develop new products for the public and defense sectors — has been an exciting process,” says Aleister Saunders, Drexel University’s senior vice provost for research and a leader of its functional fabrics center. “Seeing the success we’ve already had in recruiting partners at the local level leads me to believe that on a national level, these centers of innovation will be able to leverage intellectual capital and regional manufacturing expertise to drive forward new ideas and new applications that will revolutionize textile manufacturing across the nation.”

“Revolutionary fabrics and fibers are modernizing everything from battlefield communication to medical care,” says U.S. Congressmen Joe Kennedy III (D-Mass.). “That the Commonwealth would be chosen to lead the way is no surprise. From Lowell to Fall River, our ability to merge cutting-edge technology with age-old ingenuity has sparked a new day for the textile industry. With its unparalleled commitment to innovation, MIT is the perfect epicenter for scaling these efforts. I applaud President Reif, Professor Fink, and all of the partners involved for this tremendous success.”

The innovations that led to the “internet of things” and the widespread incorporation of digital technology into manufacturing have brought about a revolution whose potential is unlimited and will generate “brilliant ideas that people will be able to bring to this task of making sure that America stays number one in each and every one of these fields,” said Senator Ed Markey (D-Mass.) at the MIT event. “The new institute we are announcing today will help ensure that both Massachusetts and the United States can expand our technological edge in a new generation of fiber science.”

A wide range of industries are expected to benefit from these revolutionary fibers and textiles, including apparel, consumer products, automotive, medical devices, and consumer electronics. “Fibers and fabrics are ubiquitous,” Fink says. “Our institute will go everywhere a fiber and fabric goes.”

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Quantum dots enhance light-to-current conversion in layered semiconductors

Single nanocrystal spectroscopy identifies the interaction between zero-dimensional CdSe/ZnS nano crystals (quantum dots) and two-dimensional layered tin disulfide as a non-radiative energy transfer, whose strength increases with increasing …more

Harnessing the power of the sun and creating light-harvesting or light-sensing devices requires a material that both absorbs light efficiently and converts the energy to highly mobile electrical current. Finding the ideal mix of properties in a single material is a challenge, so scientists have been experimenting with ways to combine different materials to create “hybrids” with enhanced features.

In two just-published papers, scientists from the U.S. Department of Energy’s Brookhaven National Laboratory, Stony Brook University, and the University of Nebraska describe one such approach that combines the excellent light-harvesting properties of quantum dots with the tunable electrical conductivity of a layered tin disulfide semiconductor. The hybrid material exhibited enhanced light-harvesting properties through the absorption of light by the quantum dots and their energy transfer to tin disulfide, both in laboratory tests and when incorporated into electronic devices. The research paves the way for using these materials in optoelectronic applications such as energy-harvesting photovoltaics, light sensors, and light emitting diodes (LEDs).

According to Mircea Cotlet, the physical chemist who led this work at Brookhaven Lab’s Center for Functional Nanomaterials (CFN), a DOE Office of Science User Facility, “Two-dimensional metal dichalcogenides like tin disulfide have some promising properties for solar energy conversion and photodetector applications, including a high surface-to-volume aspect ratio. But no semiconducting material has it all. These materials are very thin and they are poor light absorbers. So we were trying to mix them with other nanomaterials like light-absorbing quantum dots to improve their performance through energy transfer.”

One paper, just published in the journal ACS Nano, describes a fundamental study of the hybrid quantum dot/tin disulfide material by itself. The work analyzes how light excites the quantum dots (made of a cadmium selenide core surrounded by a zinc sulfide shell), which then transfer the absorbed energy to layers of nearby tin disulfide.

“We have come up with an interesting approach to discriminate energy transfer from charge transfer, two common types of interactions promoted by light in such hybrids,” said Prahlad Routh, a graduate student from Stony Brook University working with Cotlet and co-first author of the ACS Nano paper. “We do this using single nanocrystal spectroscopy to look at how individual quantum dots blink when interacting with sheet-like tin disulfide. This straightforward method can assess whether components in such semiconducting hybrids interact either by energy or by charge transfer.”

The researchers found that the rate for non-radiative energy transfer from individual quantum dots to tin disulfide increases with an increasing number of tin disulfide layers. But performance in laboratory tests isn’t enough to prove the merits of potential new materials. So the scientists incorporated the hybrid material into an electronic device, a photo-field-effect-transistor, a type of photon detector commonly used for light sensing applications.

As described in a paper published online March 24 in Applied Physics Letters, the hybrid material dramatically enhanced the performance of the photo-field-effect transistors-resulting in a photocurrent response (conversion of light to electric current) that was 500 percent better than transistors made with the tin disulfide material alone.

“This kind of energy transfer is a key process that enables photosynthesis in nature,” said Chang-Yong Nam, a materials scientist at Center for Functional Nanomaterials and co-corresponding author of the APL paper. “Researchers have been trying to emulate this principle in light-harvesting electrical devices, but it has been difficult particularly for new material systems such as the tin disulfide we studied. Our device demonstrates the performance benefits realized by using both energy transfer processes and new low-dimensional materials.”

Cotlet concludes, “The idea of ‘doping’ two-dimensional layered materials with quantum dots to enhance their light absorbing properties shows promise for designing better solar cells and photodetectors.”

Explore further: Small size enhances charge transfer in quantum dots

More information: Yuan Huang et al. Hybrid quantum dot-tin disulfide field-effect transistors with improved photocurrent and spectral responsivity, Applied Physics Letters (2016). DOI: 10.1063/1.4944781

Huidong Zang et al. Nonradiative Energy Transfer from Individual CdSe/ZnS Quantum Dots to Single-Layer and Few-Layer Tin Disulfide, ACS Nano (2016). DOI: 10.1021/acsnano.6b01538

Journal reference: ACS Nano

Read more at: http://phys.org/news/2016-04-quantum-dots-light-to-current-conversion-layered.html#jCp

Read more at: http://phys.org/news/2016-04-quantum-dots-light-to-current-conversion-layered.html#jCp

Cornell University: Quantum Dot Solids for Enhanced Energy Absorption and Light Emission

Just as the single-crystal silicon wafer forever changed the nature of communication 60 years ago, a group of Cornell researchers is hoping its work with quantum dot solids – crystals made out of crystals – can help usher in a new era in electronics.

The team, led by Tobias Hanrath, associate professor in the Robert Frederick Smith School of Chemical and Biomolecular Engineering, and graduate student Kevin Whitham, has fashioned two-dimensional superstructures out of single-crystal building blocks. Through a pair of chemical processes, the lead-selenium nanocrystals are synthesized into larger crystals, then fused together to form atomically coherent square superlattices.

The difference between these and previous crystalline structures is the atomic coherence of each 5-nanometer crystal (a nanometer is one-billionth of a meter). They’re not connected by a substance between each crystal – they’re connected to each other. The electrical properties of these superstructures potentially are superior to existing semiconductor nanocrystals, with anticipated applications in energy absorption and light emission.

“As far as level of perfection, in terms of making the building blocks and connecting them into these superstructures, that is probably as far as you can push it,” Hanrath said, referring to the atomic-scale precision of the process.

Watch Video: “Assembling Quantum Dots Into Superlattices”

Associate professor Tobias Hanrath explains his group’s work on assembling quantum dots into ordered, two-dimensional superlattices, the subject of a paper published Feb. 22 in Nature Materials. The work has potential applications in optoelectronics. Credit: Cornell University

The Hanrath group’s paper, “Charge transport and localization in atomically coherent quantum dot solids,” is published in this month’s issue of Nature Materials.

This latest work has grown out of previous published research by the Hanrath group, including a 2013 paper published in Nano Letters that reported a new approach to connecting quantum dots through controlled displacement of a connector molecule, called a ligand. That paper referred to “connecting the dots” – i.e. electronically coupling each quantum dot – as being one of the most persistent hurdles to be overcome.

That barrier seems to have been cleared with this new research. The strong coupling of the nanocrystals leads to formation of energy bands that can be manipulated based on the crystals’ makeup, and could be the first step toward discovering and developing other artificial materials with controllable electronic structure.

Still, Whitham said, more work must be done to bring the group’s work from the lab to society. The structure of the Hanrath group’s superlattice, while superior to ligand-connected nanocrystal solids, still has multiple sources of disorder due to the fact that all nanocrystals are not identical. This creates defects, which limit electron wave function.

“I see this paper as sort of a challenge for other researchers to take this to another level,” Whitham said. “This is as far as we know how to push it now, but if someone were to come up with some technology, some chemistry, to provide another leap forward, this is sort of challenging other people to say, ‘How can we do this better?'”

Hanrath said the discovery can be viewed in one of two ways, depending on whether you see the glass as half empty or half full.

“It’s the equivalent of saying, ‘Now we’ve made a really large single-crystal wafer of silicon, and you can do good things with it,'” he said, referencing the game-changing communications discovery of the 1950s. “That’s the good part, but the potentially bad part of it is, we now have a better understanding that if you wanted to improve on our results, those challenges are going to be really, really difficult.”

Explore further: Nanocrystal infrared LEDs can be made cheaply

More information: Kevin Whitham et al. Charge transport and localization in atomically coherent quantum dot solids, Nature Materials (2016). DOI: 10.1038/nmat4576

Journal reference: Nature Materials

 

 

 

Rice U. Researchers Fine-Tune Quantum Dots from Coal

Graphene quantum dots made from coal, introduced in 2013 by the Rice University lab of chemist James Tour, can be engineered for specific semiconducting properties in either of two single-step processes.

In a new study this week in the American Chemical Society journal Applied Materials & Interfaces, Tour and colleagues demonstrated fine control over the graphene oxide dots’ size-dependent band gap, the property that makes them semiconductors. Quantum dots are semiconducting materials that are small enough to exhibit quantum mechanical properties that only appear at the nanoscale.

Tour’s group found they could produce quantum dots with specific semiconducting properties by sorting them through ultrafiltration, a method commonly used in municipal and industrial water filtration and in food production.

The other single-step process involved direct control of the reaction temperature in the oxidation process that reduced coal to quantum dots. The researchers found hotter temperatures produced smaller dots, which had different semiconducting properties.

Tour said graphene quantum dots may prove highly efficient in applications ranging from medical imaging to additions to fabrics and upholstery for brighter and longer-lasting colors. “Quantum dots generally cost about $1 million per kilogram and we can now make them in an inexpensive reaction between coal and acid, followed by separation. And the coal is less than $100 per ton.”

The dots in these experiments all come from treatment of anthracite, a kind of coal. The processes produce batches in specific sizes between 4.5 and 70 nanometers in diameter.

Enlarge

Rice University scientists have produced graphene quantum dots produced from coal with tuned band gaps and photoluminescent properties. These quantum dots, seen with an electron microscope, average 70 nanometers in diameter. Credit: Tour Group/Rice University

Graphene quantum dots are photoluminescent, which means they emit light of a particular wavelength in response to incoming light of a different wavelength. The emitted light ranges from green (smaller dots) to orange-red (larger dots). Because the emitted color also depends on the dots’ size, this property can also be tuned, Tour said. The lab found quantum dots that emit blue light were easiest to produce from bituminous coal.

The researchers suggested their quantum dots may also enhance sensing, electronic and photovoltaic applications. For instance, catalytic reactions could be enhanced by manipulating the reactive edges of quantum dots. Their fluorescence could make them suitable for metal or chemical detection applications by tuning to avoid interference with the target materials’ emissions.

Enlarge

Rice University scientists have produced graphene quantum dots produced from coal with tuned band gaps and photoluminescent properties. These quantum dots are about 4.5 nanometers in diameter. Credit: Tour Group/Rice University

Explore further: Making quantum dots glow brighter

Read more at: http://phys.org/news/2015-03-fine-tune-quantum-dots-coal.html#jCp

Rice University: Silicon Oxide Memories Catch Manufacturers’ Eye

Rice’s silicon oxide memories catch manufacturers’ eye: Use of porous silicon oxide reduces forming voltage, improves manufacturability

Houston, TX | Posted on July 10th, 2014

Rice University’s breakthrough silicon oxide technology for high-density, next-generation computer memory is one step closer to mass production, thanks to a refinement that will allow manufacturers to fabricate devices at room temperature with conventional production methods.

First discovered five years ago, Rice’s silicon oxide memories are a type of two-terminal, “resistive random-access memory” (RRAM) technology. In a new paper available online in the American Chemical Society journal Nano Letters, a Rice team led by chemist James Tour compared its RRAM technology to more than a dozen competing versions.

“This memory is superior to all other two-terminal unipolar resistive memories by almost every metric,” Tour said. “And because our devices use silicon oxide — the most studied material on Earth — the underlying physics are both well-understood and easy to implement in existing fabrication facilities.” Tour is Rice’s T.T. and W.F. Chao Chair in Chemistry and professor of mechanical engineering and nanoengineering and of computer science.

Tour and colleagues began work on their breakthrough RRAM technology more than five years ago. The basic concept behind resistive memory devices is the insertion of a dielectric material — one that won’t normally conduct electricity — between two wires. When a sufficiently high voltage is applied across the wires, a narrow conduction path can be formed through the dielectric material.

The presence or absence of these conduction pathways can be used to represent the binary 1s and 0s of digital data. Research with a number of dielectric materials over the past decade has shown that such conduction pathways can be formed, broken and reformed thousands of times, which means RRAM can be used as the basis of rewritable random-access memory.

RRAM is under development worldwide and expected to supplant flash memory technology in the marketplace within a few years because it is faster than flash and can pack far more information into less space. For example, manufacturers have announced plans for RRAM prototype chips that will be capable of storing about one terabyte of data on a device the size of a postage stamp — more than 50 times the data density of current flash memory technology.

The key ingredient of Rice’s RRAM is its dielectric component, silicon oxide. Silicon is the most abundant element on Earth and the basic ingredient in conventional microchips. Microelectronics fabrication technologies based on silicon are widespread and easily understood, but until the 2010 discovery of conductive filament pathways in silicon oxide in Tour’s lab, the material wasn’t considered an option for RRAM.

Since then, Tour’s team has raced to further develop its RRAM and even used it for exotic new devices like transparent flexible memory chips. At the same time, the researchers also conducted countless tests to compare the performance of silicon oxide memories with competing dielectric RRAM technologies.

“Our technology is the only one that satisfies every market requirement, both from a production and a performance standpoint, for nonvolatile memory,” Tour said. “It can be manufactured at room temperature, has an extremely low forming voltage, high on-off ratio, low power consumption, nine-bit capacity per cell, exceptional switching speeds and excellent cycling endurance.”

This scanning electron microscope image and schematic show the design and composition of new RRAM memory devices based on porous silicon oxide that were created at Rice University.

Credit: Tour Group/Rice University

In the latest study, a team headed by lead author and Rice postdoctoral researcher Gunuk Wang showed that using a porous version of silicon oxide could dramatically improve Rice’s RRAM in several ways. First, the porous material reduced the forming voltage — the power needed to form conduction pathways — to less than two volts, a 13-fold improvement over the team’s previous best and a number that stacks up against competing RRAM technologies. In addition, the porous silicon oxide also allowed Tour’s team to eliminate the need for a “device edge structure.”

“That means we can take a sheet of porous silicon oxide and just drop down electrodes without having to fabricate edges,” Tour said. “When we made our initial announcement about silicon oxide in 2010, one of the first questions I got from industry was whether we could do this without fabricating edges. At the time we could not, but the change to porous silicon oxide finally allows us to do that.”

Wang said, “We also demonstrated that the porous silicon oxide material increased the endurance cycles more than 100 times as compared with previous nonporous silicon oxide memories. Finally, the porous silicon oxide material has a capacity of up to nine bits per cell that is highest number among oxide-based memories, and the multiple capacity is unaffected by high temperatures.”

Tour said the latest developments with porous silicon oxide — reduced forming voltage, elimination of need for edge fabrication, excellent endurance cycling and multi-bit capacity — are extremely appealing to memory companies.

“This is a major accomplishment, and we’ve already been approached by companies interested in licensing this new technology,” he said.

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Study co-authors — all from Rice — include postdoctoral researcher Yang Yang; research scientist Jae-Hwang Lee; graduate students Vera Abramova, Huilong Fei and Gedeng Ruan; and Edwin Thomas, the William and Stephanie Sick Dean of Rice’s George R. Brown School of Engineering, professor in mechanical engineering and materials science and in chemical and biomolecular engineering.