Researchers find a two-dimensional, self-assembling material that might produce solar cells or transistors.
David L. Chandler | MIT News Office
April 30, 2014
Researchers around the world have been working to harness the unusual properties of graphene, a two-dimensional sheet of carbon atoms. But graphene lacks one important characteristic that would make it even more useful: a property called a bandgap, which is essential for making devices such as computer chips and solar cells.
Now, researchers at MIT and Harvard University have found a two-dimensional material whose properties are very similar to graphene, but with some distinct advantages — including the fact that this material naturally has a usable bandgap.
The research, just published online in the Journal of the American Chemical Society, was carried out by MIT assistant professor of chemistry Mircea Dincă and seven co-authors.
The new material, a combination of nickel and an organic compound called HITP, also has the advantage of self-assembly: Its constituents naturally assemble themselves, a “bottom-up” approach that could lend itself to easier manufacturing and tuning of desired properties by adjusting relative amounts of the ingredients.
Research on such two-dimensional materials, which often possess extraordinary properties, is “all the rage these days, and for good reason,” Dincă says. Graphene, for example, has extremely good electrical and thermal conductivity, as well as great strength. But its lack of a bandgap forces researchers to modify it for certain uses — such as by adding other molecules that attach themselves to its structure — measures that tend to degrade the properties that made the material desirable in the first place.
The new compound, Ni3(HITP)2, shares graphene’s perfectly hexagonal honeycomb structure. What’s more, multiple layers of the material naturally form perfectly aligned stacks, with the openings at the centers of the hexagons all of precisely the same size, about 2 nanometers (billionths of a meter) across.
In these initial experiments, the researchers studied the material in bulk form, rather than as flat sheets; Dincă says that makes the current results — including excellent electrical conductivity — even more impressive, since these properties should be better yet in a 2-D version of the material. “There’s every reason to believe that the properties of the particles are worse than those of a sheet,” he says, “but they’re still impressive.”
What’s more, this is just the first of what could be a diverse family of similar materials built from different metals or organic compounds. “Now we have an entire arsenal of organic synthesis and inorganic synthesis,” Dincă says, that could be harnessed to “tune the properties, with atom-like precision and virtually infinite tunability.”
Such materials, Dincă says, might ultimately lend themselves to solar cells whose ability to capture different wavelengths of light could be matched to the solar spectrum, or to improved supercapacitors, which can store electrical energy until it’s needed.
In addition, the new material could lend itself to use in basic research on the properties of matter, or to the creation of exotic materials such as magnetic topological insulators, or materials that exhibit quantum Hall effects. “They’re in the same class of materials that have been predicted to have exotic new electronic states,” Dincă says. “These would be the first examples of these effects in materials made out of organic molecules. People are excited about that.”
Pingyun Feng, a professor of chemistry at the University of California at Riverside who was not involved in this work, says the approach used by this team is “novel and surprising,” and that “the quality of this work, from the synthetic design strategy to the probing of the structural details and to the discovery of exceptional electrical conductivity, is outstanding.” She adds that this finding “represents a major advance in the synthetic design of novel semiconducting materials.”
The work was supported by the U.S. Department of Energy and the Center for Excitonics at MIT.
According to a new research report published by Allied Market Research (Portland, OR), the global market for quantum dots (QDs) reached $316 million in 2013 and is expected to grow to $5.04 billion by 2020 at a compound annual growth rate (CAGR) of 29.9% in the period between 2014 and 2020.
However, the volume consumption will grow at a much faster rate of 116.5% during the same period, to reach 72 tons in 2020 — the result of a drop in QD price over time, attributable to the refinement of mass-production processes and high volume demand.
The report is called “Quantum Dot (QD) Market–Global Analysis, Growth, Trends, Opportunities, Size, Share and Forecast through 2020.”
Key drivers for growth of the QD market are efficient conversion of solar energy into power, the rising use of display devices, and utility in multiple applications, according to the report. Display and lighting-equipment manufacturers are eager to bring out QD-based products, which are currently the prime driver of QD market growth.
QD light emitters will be big
As for end-use categories, QD light-emitting devices will have the highest CAGR of 39% between now and 2020, says the report; other categories with lesser CAGRs include QD displays, lasers, chips, sensors, medical devices, and photovoltaics.
And as for materials, indium arsenide (InAs) QDs will have a leading market share of $1.18 billion in 2020, with cadmium selenide (CdSe), cadmium sulfide (CdS), cadmium telluride (CdTe), and silicon (Si) all runners-up.
Optoelectronics will lead revenue share at $1.77 billion in 2020, with other contenders being quantum optics, QD-based security and surveillance, renewable energy, and biological/healthcare imaging.
“The QD display market is set to grow exponentially as many companies such as Sony Corp., LG Display, etc. are getting into alliances with QD technology providers to commercialize QD displays, especially TV sets,” note analysts Shreyas Naidu and Priyanka Gotsurve. “QD technology enhances the color display by at least 50% and it is also an energy efficient technology.”
Some factors, such as high cost of technology and slow adoption due to extended research, are currently slowing market growth, although the growth of mass manufacturing and bulk purchasing will quickly negate the cost constraints. Further penetration of the technology in newer applications such as security and defense, food, and packaging will provide the essential future growth thrust to the market. Future use of newer and more cost effective materials will give QDs an added competitive edge over other materials such as organic dyes.
Among geographic markets, North America has the highest revenue share due to early adoption. The region is expected to grow consistently and attain revenue of $1.92 billion by 2020.However, the Asia-Pacific market is expected to have the highest CAGR of 30.4% for the 2013-2020 analysis period.
Background
Quantum dot is small semiconductor in crystal format that is used in business verticals that use display and monitor devices and many other types of equipment. Global Nano-optimized market is expected to reach 3 trillion by 2015. Increasing demand for optimized devices with better performance and resolution quality is a major driving force to adopt quantum dot technology into various application areas. Brightness of quantum dots is 10-20 times higher than organic dyes. As the semiconductor material shrinks to quantum-dot level, it helps in altering the light wavelength material and covert material from insulator to conductor.
Quantum dot is semiconductor that can be used for different devices instead of searching for new semiconductor with special chemical composition. Major application market for quantum dot is Display and Monitor as quantum dots are used in LED. However, the process of manufacturing Blue quantum dots in size that is smaller than average is very difficult over other colors of quantum dots, this is acting as major limiting factor to adopt quantum dots in display and monitor products. Despite of few disadvantages, quantum dots are going to capture attention by major players, but it is very difficult for manufacturers to analyze potential application market of quantum dots. This report covers potential application segment and revenue generated by each segment. The global QD market is expected to grow from $316 million in 2013 to $5,040 million ($5.04 Billion) in 2020 at a CAGR of 29.9% for the analysis period (2013-2020).
Global QD market by application
The QD market is segmented into various applications such as biological imaging, optoelectronics, quantum optics, security & surveillance, and renewable energy. The biological imaging market is the most mature market in terms of revenue and it is expected to have consistent growth in the market. However, the optoelectronics application is expected to have the highest growth potential for the analysis period 2013 and 2020. The renewable energy application is the next fastest growing application in the QD market.
Global QD market by devices
The quantum dot based devices are the end-users of the technology as these particles are used to develop devices for various applications. The end-user segment consists of QD Medical Devices, QD LCD and LED Display Devices, QD Laser Devices, QD Photovoltaic Devices, QD Chip, QD Sensors, and QD LED Lighting Devices. The QD based medical devices currently have the highest market share as medical scientists have been engaged in developing these devices for more than two decades. However, the display devices are expected to have the highest growth rate in the QD market, as the technology enhances the color quality of display devices and saves energy. Photovoltaic devices are expected to have the second highest growth rate after display devices.
Global QD market by technology
QDs are produced by using various technologies such as colloidal synthesis, fabrication, viral assembly, electrochemical assembly, bulk manufacturing and cadmium free QD technology. Colloidal synthesis is the most popular technology in the market currently, as it has the potential to produce QDs at a large scale. However, it is expected that bulk manufacturing would have the highest revenue share with the highest growth rate due to its ability of large scale QD production with better quality. The cadmium free QD technology is expected to have the second highest growth, as it would be used in consumer applications, since cadmium has restrictions for use in these applications.
Global QD market by material
QDs are produced by processing some materials such as Cadmium Selenide, Cadmium Sulphide, Cadmium Telluride, Indium Arsenide, and Silicon. Cadmium Selenide was the most commonly used material to produce QDs in 2013 followed by Cadmium Sulfide, as these were the first materials that were ever used in the process. However, Indium Arsenide would have the highest growth rate for the analysis period 2013-2020 along with the highest revenue by 2020. The silicon material would have the second highest growth rate as it is observed that the light emission capacity of silicon is in excess of 70% and can be used in electronic devices to increase efficiency.
Global QD market by geography
The QD market is geographically segmented into North America, Europe, Asia-Pacific and Rest of the World (RoW). Currently, North America has the highest revenue share in the market followed by Europe due to early adoption of the QD technology. However, for the analysis period of 2012-2020, it is expected that the Asia-Pacific region would have the highest growth rate followed by the RoW region.
Global QD market competitive analysis
Key Companies profiles included in this report are Sony Corporation; Altair Nanotechnology,Inc; Evident Technologies, LG Display, Life Technologies Corporation, Microvision Inc; Quantum Material Corporation; Samsung Electronics Co. Ltd, Nexxus Lighting Microvision Inc. The companies have opted for partnerships and collaborations as a key strategy so that they can share the expertise to develop better QD based products and solutions, as it is an evolving technology.
Global QD market high level analysis
The report analyses the potency of suppliers and buyers along with threats of new entrants and substitute products based on the Porter’s five force analysis. The report also analyses the impact of the drivers, restraints and opportunities of the market as per the current market trends and projected future scenario. The key investment pockets are analyzed in the report based on the growth estimations of the application segment.
Reason for doing the study
The commercial prospects of the market are inclined towards growth due to the efficiency of QDs to produce energy efficient and flexible products and solutions. The market is currently at a pre-commercialized stage and the report covers the research efforts undertaken to commercialize the market. The market estimation are made on the basis of some assumptions of the past years volume production and expected production in the future and projected price fluctuations. The report gives a deep dive-analysis on applications in various sectors of the market to give market players an understanding about the important growth potential to maximize profits. The report also studies the impact and penetration of the QD technology in various geographic regions so that companies can understand end-user preferences to gain competitive advantage.
Key Benefits
This report analyses the factors that are driving and limiting the growth of the market
Market estimations are done according to the market trends for the period 2013-2020
Analysis of key strategies adopted by market players through their press releases would assist in providing in-depth understanding of the market intelligence
Deep-dive analysis of various geographies would give an understanding of the trends in various regions so that companies can make region specific plans
In-depth analysis of segments such as applications, end-users (devices), technologies and materials provide insights that would allow companies to gain competitive edge
Flexible, indium-free solar cell with a transparent conductive film produced using the new Empa method
Transparent conductive films are now an integral part of our everyday lives. Whether in smartphones, tablets, laptops, flat screens or (on a larger scale) in solar cells. Yet they are expensive and complex to manufacture. Now, researchers at Empa have succeeded in developing a method of producing such TCO films, as they are known, that is not only cheaper, but also simpler and more environmentally friendly.
It is a requirement of the touchscreens for all our everyday gadgets that they are transparent and at the same time electrically conductive. Solar cells are also unable to operate without such a film, which allows sunlight to pass through it, but can also conduct the current generated. Conventional “transparent conductive oxide” (TCO) films consist of a mixture of indium and tin oxide. Indium in very much in demand in the electronics industry, but is rare, and therefore expensive.
A cheaper option (at least in terms of the materials used) employs zinc oxide mixed with aluminium, which is usually applied to the substrate in a high vacuum by means of plasma sputtering. However, the manufacturing process is complex, making it similarly expensive. In addition, it is energy-intensive and therefore not ideal from an ecological perspective. Empa researchers at the Laboratory for Thin Films and Photovoltaics have now developed a water-based method of applying a TCO film made of aluminium and zinc salts onto a substrate—without a vacuum.
Less energy consumption
The transparent conductive film under an electron microscope: the crystals are grown widthways, close together using a “molecular lid” – giving the film optimum conductivity.Another advantage of the new method is that during the last stage of production, in which the TCO film is “cured”, the substrate does not have to be heated to 400 to 600 degrees as was previously the case, but only to 90 degrees. “This means that our method is not only cheaper and more environmentally friendly, but also requires less energy and it is even possible to use more heat-sensitive substrates, such as flexible plastics”, explains Harald Hagendorfer from the research team.
The biggest difference, however, lies in the principle behind the manufacturing process. Whereas with the sputtering method, the TCO film is deposited onto the substrate in a high vacuum using a high-energy plasma, with the Empa method, this occurs through a type of molecular self-organization. Thus, the TCO film grows “by itself”—with no subsequent high-temperature thermal treatment. A short irradiation process with a UV lamp is sufficient to produce excellent conductivity.
Yet here too, a problem had to be overcome: aluminium zinc oxide (AZO) prefers to grow tapering upwards—like stalagmites in a limestone cave. For optimum conductivity, however, there must be no gaps between the “pillars”. The simple solution devised by the Empa team was to use a “molecular lid” during the crystal growing process. Thus, the material can only grow to a limited height and instead grows widthways, resulting in a compact film which is transparent and has optimum conductivity.
TCO films to become even more efficient
The Empa team, led by Ayodhya Tiwari, is now working to further improve the AZO films. In terms of electrical conductivity and transparency, they can already compete with indium-containing TCO films, but some optimisation is still required with regard to their use in solar cells. Tiwari and his colleagues want to reduce the TCO film thickness from one to two microns to just a few hundred nanometres. This would allow the AZO films to be used in flexible solar cells, further reducing the amount of material used. Tiwari’s team is also currently working with another Empa research group on the indium-free production of organic solar cells, which would make the process cheaper and more sustainable. There certainly seems to be a considerable amount of interest in the new method. Industrial project partners are already on board, opening up the possibility that Empa TCO films may soon be manufactured on a large scale.
A substrate is introduced into the aqueous aluminium zinc oxide solution (AZO); a polycrystalline ordered film then grows on it. Then, UV light is all that is required to make the transparent film conductive.
The courtyard between MIT.nano and Building 4 looking west from Building 8 toward the Great Dome. Image: Wilson Architects
Starting in 2018, researchers from across MIT will be able to take advantage of comprehensive facilities for nanoscale research in a new building to be constructed at the very heart of the Cambridge campus.
The 200,000-square-foot building, called “MIT.nano,” will house state-of-the-art cleanroom, imaging, and prototyping facilities supporting research with nanoscale materials and processes—in fields including energy, health, life sciences, quantum sciences, electronics, and manufacturing. An estimated 2,000 MIT researchers may ultimately make use of the building, says electrical engineering professor Vladimir Bulović, faculty lead on the MIT.nano project and associate dean for innovation in the School of Engineering.
“MIT.nano will sit at the heart of our campus, and it will be central to fulfilling MIT’s mission in research, education, and impact,” says MIT President L. Rafael Reif. “The capabilities it provides and the interdisciplinary community it inspires will keep MIT at the forefront of discovery and innovation, and give us the power to solve urgent global challenges. By following the lead of faculty and student interest, MIT has a long tradition of placing bold bets on strategic future technologies, and we expect MIT.nano to pay off in the same way, for MIT and for the world.”
MIT.nano will house two interconnected floors of cleanroom laboratories containing fabrication spaces and materials growth laboratories, greatly expanding the Institute’s capacity for research involving components that are measured in billionths of a meter—a scale at which cleanliness is paramount, as even a single speck of dust vastly exceeds the nanoscale. The building will also include the “quietest” space on campus—a floor optimized for low vibration and minimal electromagnetic interference, dedicated to advanced imaging technologies—and a floor of teaching laboratory space. Finally, the facility will feature an innovative teaching and research space, known as a Computer-Aided Visualization Environment (CAVE), allowing high-resolution views of nanoscale features.
“The tools of nanotechnology will play a critical part in how many engineering disciplines solve the problems of the 21st century, and MIT.nano will shape the Institute’s role in these advances,” says Ian A. Waitz, dean of the School of Engineering and the Jerome C. Hunsaker Professor of Aeronautics and Astronautics. “This project represents one of the largest commitments to research in MIT’s history. MIT.nano will carry the last two decades of research into new realms of application and discovery.”
“Usually we talk about how science enables new technology, but discovery is a two-way street,” adds Maria Zuber, MIT’s vice president for research and the E.A. Griswold Professor of Geophysics. “In MIT.nano, technology will advance basic science through the extraordinary observations that will be possible in this state-of-the-art facility.”
MIT.nano will be a 200,000-square-foot research facility for nanoscale research constructed at the very heart of the MIT campus. The building will house state-of-the-art cleanroom, imaging, and prototyping facilities supporting research with nanoscale materials and processes—in fields including energy, health, life sciences, quantum sciences, electronics, and manufacturing.
The four-level MIT.nano will replace the existing Building 12, and will retain its number, occupying a space alongside the iconic Great Dome. It will be interconnected with neighboring buildings, and accessible from MIT’s Infinite Corridor—meaning, Bulović says, that the new facility will be just a short walk from the numerous departments that will use its tools.
“This building needs to be centrally located, because nanoscale research is now central to so many disciplines,” says Bulović, who is the Fariborz Maseeh Professor in Emerging Technology at MIT.
Users of the new facility, he adds, are expected to come from more than 150 research groups at MIT. They will include, for example, scientists who are working on methods to “print” parts of human organs for transplantation; who are creating superhydrophobic surfaces to boost power-plant efficiency; who work with nanofluids to design new means of locomotion for machines, or new methods for purifying water; who aim to transform the manufacturing of pharmaceuticals; and who are using nanotechnology to reduce the carbon footprint of concrete, the world’s most ubiquitous building material.
The research that will take place in MIT.nano could also help the world meet its growing energy needs, Bulović says. For example, cloud computing already consumes 1.3% of the world’s electricity; as this technology proliferates, its energy use is projected to grow a thousandfold over the coming decade. Hardware based on nanoscale switching elements—a new technology now being pursued by MIT researchers—could prove crucial in reducing the energy footprint of cloud computing.
“But we have many urgent challenges that existing technology cannot address,” Bulović says. “If we want to make sweeping change—more than incremental progress—in the most urgent technical areas, we need this building and the tools of nanoscience and nanotechnology housed within it.”
“The need for advanced facilities to support nanoscale research was identified in 2011 as the Institute’s highest academic priority as part of the MIT 2030 process to envision how our campus might evolve to meet future needs for research and education,” says Israel Ruiz, MIT’s executive vice president and treasurer. “It is wonderful to see we are boldly moving to accomplish our goal.”
Cleanroom facilities, by their nature, are among the most energy-intensive buildings to operate: Enormous air-handling machinery is needed to keep their air filtered to an extraordinarily high standard. Travis Wanat, the senior project manager at MIT who is overseeing the MIT.nano project, explains that while ventilation systems for ordinary offices or classrooms are designed to exchange the air two to six times per hour, cleanroom ventilation typically requires a full exchange 250 times an hour. The fans and filters necessary to handle this volume of air require an entire dedicated floor above each floor of cleanrooms in MIT.nano.
But MIT.nano will incorporate many energy-saving features: Richard Amster, director of campus engineering and construction, has partnered with Julie Newman, MIT’s director of sustainability. Together, they are working within MIT, as well as with the design and contracting teams, “to develop the most efficient building possible for cleanroom research and imaging,” Amster says.
Toward that end, MIT.nano will use heat-recovery systems on the building’s exhaust vents. The building will also be able to sense the local cleanroom environment and adjust the need for air exchange, dramatically reducing MIT.nano’s energy consumption. Dozens of other features aim to improve the building’s efficiency and sustainability.
Despite MIT.nano’s central location, the floor devoted to advanced imaging technology will have “more quiet space than anywhere on campus,” Bulović says: The facility is situated as far as possible from the noise of city streets and subway and train lines that flank MIT’s campus.
Indeed, protection from these sources of noise and mechanical vibration dictated the building’s location, from among five campus sites that were considered. According to national standards on ambient vibration, Bulović says, parts of MIT.nano will rate two levels better than the standard typically used for such high-quality imaging spaces.
Another important goal of the building’s design—by Wilson Architects in Boston—is the creation of environments that foster interactions among users, including those from different disciplines. The building’s location at a major campus “crossroads,” its extensive use of glass walls that allow views into lab and cleanroom areas, and its soaring lobbies and other common areas are all intended to help foster such interactions.
“Nanoscale research is inherently interdisciplinary, and this building was designed to encourage collaboration,” Bulović says.
“MIT’s enduring leadership in technology and science is made possible by the interconnective nature of our community, and our total potential is greater than the sum of our parts,” adds Timothy Swager, the John D. MacArthur Professor of Chemistry. “At an intellectual level this is driven by our collective commitment to excellence and innovation, but the physical proximity of researchers at MIT is the heart and soul of this special atmosphere. MIT.nano will serve to enhance these interactions and provide an opportunity-rich venue where chemistry, biology, physics, and engineering all converge to create devices and understanding that will empower MIT researchers to reach new heights in innovation.”
The choice of MIT.nano’s central location is not without compromise, Bulović says: There is very limited access to the construction site—only three access roads, each with limited headroom—so planning for the activities of construction and delivery vehicles, and for the demolition of the current Building 12 and construction of MIT.nano, will present a host of logistical challenges. “It’s like building a ship in a bottle,” Bulović says.
But addressing those challenges will ultimately be well worth it, he says, pointing out that an estimated one-quarter of MIT’s graduate students and 20 percent of its researchers will make use of the facility. The new building “signifies the centrality of nanotechnology and nanomanufacturing for the needs of the 21st century. It will be a key innovation hub for the campus.”
All current occupants of Building 12 will be relocated by June, when underground facilities work, to enable building construction, will commence; at that point, fences will be erected around the constriction zone. The existing Building 12 will be demolished in spring 2015 and construction of MIT.nano is slated to begin in summer 2015.
Series of still scanning electron micrographs (a to d) show how the electron beam is used to create nanowires. Images: Junhao Lin /Vanderbilt
Junhao Lin, a Vanderbilt Univ. graduate student and visiting scientist at Oak Ridge National Laboratory (ORNL), has found a way to use a finely focused beam of electrons to create some of the smallest wires ever made. The flexible metallic wires are only three atoms wide: One thousandth the width of the microscopic wires used to connect the transistors in today’s integrated circuits.
Lin’s achievement is described in an article published online in Nature Nanotechnology. According to his advisor Sokrates Pantelides, a prof. of physics and engineering at Vanderbilt Univ., and his collaborators at ORNL, the technique represents an exciting new way to manipulate matter at the nanoscale and should give a boost to efforts to create electronic circuits out of atomic monolayers, the thinnest possible form factor for solid objects.
“Junhao took this project and really ran with it,” said Pantelides.
Lin made the tiny wires from a special family of semiconducting materials that naturally form monolayers. These materials, called transition-metal dichalcogenides (TMDCs), are made by combining the metals molybdenum or tungsten with either sulfur or selenium. The best-known member of the family is molybdenum disulfide, a common mineral that is used as a solid lubricant.
Atomic monolayers are the object of considerable scientific interest these days because they tend to have a number of remarkable qualities, such as exceptional strength and flexibility, transparency and high electron mobility. This interest was sparked in 2004 by the discovery of an easy way to create graphene, an atomic-scale honeycomb lattice of carbon atoms that has exhibited a number of record-breaking properties, including strength, electricity and heat conduction. Despite graphene’s superlative properties, experts have had trouble converting them into useful devices, a process materials scientists call functionalization. So researchers have turned to other monolayer materials like the TMDCs.
Other research groups have already created functioning transistors and flash memory gates out of TMDC materials. So the discovery of how to make wires provides the means for interconnecting these basic elements. Next to the transistors, wiring is one of the most important parts of an integrated circuit. Although today’s integrated circuits (chips) are the size of a thumbnail, they contain more than 20 miles of copper wiring.
“This will likely stimulate a huge research interest in monolayer circuit design,” Lin said. “Because this technique uses electron irradiation, it can in principle be applicable to any kind of electron-based instrument, such as electron-beam lithography.”
One of the intriguing properties of monolayer circuitry is its toughness and flexibility. It is too early to predict what kinds of applications it will produce, but “If you let your imagination go, you can envision tablets and television displays that are as thin as a sheet of paper that you can roll up and stuff in your pocket or purse,” Pantelides commented.
In addition, Lin envisions that the new technique could make it possible to create three-dimensional circuits by stacking monolayers “like Lego blocks” and using electron beams to fabricate the wires that connect the stacked layers.
The nanowire fabrication was carried out at ORNL in the microscopy group that was headed until recently by Stephen J. Pennycook, as part of an ongoing Vanderbilt-ORNL collaboration that combines microscopy and theory to study complex materials systems.
(Published on April 1, 2014). A cloaking paint developed by Michigan Engineers sprays on clear and dries invisible. Once dry, it guides light around an object, causing it to become transparent. (NOTE: This technology only works one day each year on April 1.)
As nanotechnology blurs the line between science and science fiction, Christoph Ellison has developed a paint that guides rays of light around an object. Still in development, the distortions allow the outline of the object to be seen, preventing true invisibility.
About the Professor: Christoph Ellison is an Assistant Professor at the University of Michigan College of Engineering (http://www.engin.umich.edu/). His research at the Center for Nano-optics includes nano-colloids, nano-gels, negative index materials and superlensing.
Battery graphite demand could double in 6 years with no growth elsewhere US automotive giant, Tesla, has revealed plans to build a new $5bn lithium-ion battery (Li-ion battery) ‘gigafactory’ which could potentially increase natural graphite demand by up to 37% by 2020.
The factory, which is forecast to start production by 2017, is expecting to have an output of 35 gWh/year by as early as 2020, which would over double the size of the current market.
Its important to stress that the plant is in the planning stage and capacities depend strongly on market demand, but Tesla believes it can be the market leader by producing low cost batteries in the USA.
In IM Data‘s calculations, Tesla’s plant – which is set to be based in the south-west USA – will consume at least 28,000 tonnes of spherical graphite every year if operating at capacity. This equates to 93,000 tonnes of flake graphite if produced to today’s standards which sees raw material wastage of up to 70%.
If achieved, battery demand for natural graphite will increase 112% from today’s levels of 83,000 tpa. This is assuming no other growth in regions such as Asia which is today’s primary consuming region.
While R&D firms have been actively exploring non-graphitic carbon anode alternatives, the position of graphite anodes as the current material of choice for Li-ion battery producers means the graphite industry is likely to be the beneficiary of this growth.
Whether Tesla plans to utilise spherical graphite – made from large natural flake graphite – or synthetic materials remains unclear.
Nonetheless, expansion of the battery market for electric vehicles (EVs) on this scale presents a valuable opportunity to graphite suppliers.
Seizing an opportunity
In 2012, consumption from the battery sector constituted 8% of global natural graphite demand.
For the natural graphite market to supply the type of market growth Tesla are forecasting, large flake graphite output will need to increase significantly over the coming years.
IM Data estimates that large flake grades (+80 mesh and larger) only made up just over 20% of total flake graphite output of 375,000 tonnes in 2013, and with competition for these grades from other traditional markets (i.e. the refractories sector), new projects are likely to be required to meet the battery market demand.
A number of junior projects are aiming to reach production over the coming 2-3 years, many boasting large flake reserves capable of supplying new hi-tech markets.
With China’s large flake reserves depleting, and the efficiency of the country’s spherodization process under question, these projects have an opportunity to play a major role in supplying emerging markets.
Tesla’s rapid EV expansion plans are, however, centered around lowering Li-ion battery costs by over 30% per kWh, which will allow the company to bring a more price competitive product to market.
Raw material costs are therefore likely to be under close scrutiny as the company gears up for production, meaning any potential graphite suppliers will have to be competitive not only with other producers but also alternative carbon anode companies.
The FOB price of Chinese uncoated spherical graphite, 99.95% C, 15 microns stands at $3,400/tonne today, while prices of coated spherical graphite – the final material used in battery anodes – is valued at around three times this level.
From Ford to Tesla?
In 1913, Henry Ford introduced the use of an assembly line in the production of the Ford Model T motor car, which revolutionised the automobile industry and brought an affordable product to market in the US.
Over a century on and Tesla’s plans to internalise its Li-ion battery production could prove just as pivotal in the emergence of the EV market, unlocking a lucrative new layer of demand for natural graphite producers.
Although the use of graphite in Li-ion battery technologies is not a new concept, the quantities used in more developed portable device markets, such as phones or tablets, are not substantial enough to be a major source of demand for flake graphite.
As much as 56kg of graphite is, however, used per EV, making the market an exciting new prospect for the graphite community which has fueled a wave of interest in recent years.
While the market has failed to expand at the rate many had forecast –both the US and China have fallen short of government growth targets – EVs present the most feasible opportunity for graphite producers to diversify from traditional industrial markets.
If Tesla manages to meet its expansion plans over the coming six years, the company is likely to further the cause of not only the EV industry, but also the graphite market in its path.
How many graphite mines will Tesla need?
Should Tesla choose to use spherical graphite sourced from natural flake as its raw material of choice, at capacity the plant will need substantial volumes.
As outlined earlier, a conservative case will see the plant demanding 93,000 tonnes of flake graphite but in a bullish case this could rise as high as 140,000 tonnes. The challenge for the graphite industry will be not only the volumes but the sufficient quantity of medium and large flake graphite.
At present, medium flake (-100 mesh) graphite from China is used to produce spherical graphite which is then coated in Japan. Should the new, more economical processing techniques take off in the next two years as expected, a large portion of this demand will be for large flake (+80 mesh) and spherical graphite production hubs will emerge in Europe and North America.
The flake footprint of each mine varies quite significantly, each with its own blend of large and medium flakes in addition to fines. Therefore a number of mines will need to be built to satisfy a Tesla plant running at full capacity.
Below, IM Data offers the following consumption scenarios for Tesla’s battery plant by 2020:
Conservative case for Tesla plant running at capacity
A new study from Los Alamos National Laboratory and the University of Milano-Bicocca demonstrates that superior light-emitting properties of quantum dots can be applied in solar energy, boosting the output of solar cells and allowing for the integration of photovoltaic-active architectural elements into buildings.
A house window that doubles as a solar panel could be on the horizon, thanks to recent quantum-dot work by Los Alamos National Laboratory researchers in collaboration with scientists from University of Milano-Bicocca (UNIMIB), Italy. Their project demonstrates that superior light-emitting properties of quantum dots can be applied in solar energy by helping more efficiently harvest sunlight.
This schematic shows how the quantum dots are embedded in the plastic matrix and capture sunlight to improve solar panel efficiency.
“The key accomplishment is the demonstration of large-area luminescent solar concentrators that use a new generation of specially engineered quantum dots,” said lead researcher Victor Klimov of the Center for Advanced Solar Photophysics (CASP) at Los Alamos.
Quantum dots are ultra-small bits of semiconductor matter that can be synthesized with nearly atomic precision via modern methods of colloidal chemistry. Their emission color can be tuned by simply varying their dimensions. Color tunability is combined with high emission efficiencies approaching 100 percent. These properties have recently become the basis of a new technology – quantum dot displays – employed, for example, in the newest generation of the Kindle Fire e-reader.
Light-harvesting antennas
A luminescent solar concentrator (LSC) is a photon management device, representing a slab of transparent material that contains highly efficient emitters such as dye molecules or quantum dots. Sunlight absorbed in the slab is re-radiated at longer wavelengths and guided towards the slab edge equipped with a solar cell.
Klimov explained, “The LSC serves as a light-harvesting antenna which concentrates solar radiation collected from a large area onto a much smaller solar cell, and this increases its power output.”
“LSCs are especially attractive because in addition to gains in efficiency, they can enable new interesting concepts such as photovoltaic windows that can transform house facades into large-area energy generation units,” said Sergio Brovelli, who worked at Los Alamos until 2012 and is now a faculty member at UNIMIB.
Because of highly efficient, color-tunable emission and solution processability, quantum dots are attractive materials for use in inexpensive, large-area LSCs. One challenge, however, is an overlap between emission and absorption bands in the dots, which leads to significant light losses due to the dots re-absorbing some of the light they produce.
“Giant” but still tiny, engineered dots
To overcome this problem the Los Alamos and UNIMIB researchers have developed LSCs based on quantum dots with artificially induced large separation between emission and absorption bands (called a large Stokes shift).
These “Stokes-shift” engineered quantum dots represent cadmium selenide/cadmium sulfide (CdSe/CdS) structures in which light absorption is dominated by an ultra-thick outer shell of CdS, while emission occurs from the inner core of a narrower-gap CdSe. The separation of light-absorption and light-emission functions between the two different parts of the nanostructure results in a large spectral shift of emission with respect to absorption, which greatly reduces losses to re-absorption.
To implement this concept, Los Alamos researchers created a series of thick-shell (so-called “giant”) CdSe/CdS quantum dots, which were incorporated by their Italian partners into large slabs (sized in tens of centimeters) of polymethylmethacrylate (PMMA). While being large by quantum dot standards, the active particles are still tiny – only about hundred angstroms across. For comparison, a human hair is about 500,000 angstroms wide.
“A key to the success of this project was the use of a modified industrial method of cell-casting, we developed at UNIMIB Materials Science Department” said Francesco Meinardi, professor of Physics at UNIMIB.
Spectroscopic measurements indicated virtually no losses to re-absorption on distances of tens of centimeters. Further, tests using simulated solar radiation demonstrated high photon harvesting efficiencies of approximately 10% per absorbed photon achievable in nearly transparent samples, perfectly suited for utilization as photovoltaic windows.
Despite their high transparency, the fabricated structures showed significant enhancement of solar flux with the concentration factor of more than four. These exciting results indicate that “Stokes-shift-engineered” quantum dots represent a promising materials platform. It may enable the creation of solution processable large-area LSCs with independently tunable emission and absorption spectra.
Funding: The Center for Advanced Solar Photophyscis (CASP) is an Energy Frontier Research Center funded by the Office of Science of the US Department of Energy.
The work of the UNIMIB team was conducted within the UNIMIB Department of Materials Science and funded by Fondazione Cariplo (2012-0844) and the European Community’s Seventh Framework Programme (FP7/2007-2013; grant agreement no. 324603).
Publication: Francesco Meinardi, et al., “Large-area luminescent solar concentrators based on ‘Stokes-shift-engineered’ nanocrystals in a mass-polymerized PMMA matrix,” Nature Photonics (2014); doi:10.1038/nphoton.2014.54
*** “Great Things from Small Things” has written and re-published many articles over the past several years on the “wee tiny” nano-materials called Quantum Dots. Their enabling applications across a broad spectrum of Markets & Industries from Electronics, Textiles, Drug Therapies, Bio-Medicines to Solar Energy Generation/ Storage and Display Screens, has been well documented. It would seem these new “wonder nano-materials” are poised to change the entire landscape of how we innovate and manufacture almost everything.
So what’s the catch? What has delayed a broader acceptance and integration of quantum dots into the marketplace? It would seem the answer lies not in the efficacy & validity of the new ‘nano-materials’ but more in the age old and time tested axiom of: “Low Cost + High Consistency + Ability to Mass Scale = Commercial Success.
A new company Nano Assembly has plans to change all that. Business Investigative writer Osama Natto highlights the High Profile Team and award winning company’s collaboration with KAUST (King Abdullah University of Science and Technology) to integrate these disruptive game changing materials in the broader marketplace for commercial success.
Article by Osama Natto
The Problem
Quantum dots are expensive enough to limit their otherwise broad applicability.
The standard way to make these semiconductor particles is to heat a solution to a high temperature in a small flask and inject a special agent. However, the solution will cool down naturally, and manual operation cannot maintain the high temperature needed for efficient production.
One can scale production of quantum dots up by using a larger flask, but this does not produce quality results. One can also use a continuous-flow reactor to benefit from higher consistency and automatic operation, as well as production of quantum dots in different sizes, but this still does not produce high-quality quantum dots.
The Solution
The Nano Assembly team has found a new method for producing quantum dots consistently and at a significantly lower price than competitors.
How the Product Works
The optical and electrical properties of quantum dots depend on their size and type. Different sizes emit different colors and exhibit a different absorption spectrum. Quantum dots must be produced according to careful standards.
The Technology Nano Assembly’s dual-stage servo control method allows the production of quantum dots without the broad peaks and troughs that come from other methods. The lower the absorption peak, the higher the quality of the quantum dots.
Where It Fits into the Market The quantum dots produced by Nano Assembly can be used anywhere that more expensively-produced quantum dots are utilized, allowing competing offerings to be replaced.
Patent Status The team has already filed for a patent and published their work in a high-impact journal.
Benefits to Saudi Economy These “low-cost and high quality quantum dots” could allow tech products already popular in Saudi Arabia, such as mobile phones, to include more efficient displays while remaining inexpensive. The team’s affordable quantum dots could also allow more people access to high-quality medical imaging, and improve solar cell technology to allow effective harvest of one of Saudi Arabia’s greatest natural resources: sunlight.
Usages
In part due to their ability to produce a rainbow of bright colors efficiently, quantum dots are used in display technologies. Since quantum dots are so tiny, they can also move anywhere in the human body, making them useful in the field of medical imaging as replacements for fluorescence-based biosensors that use organic dyes. Quantum dots can also be used as the absorbing photovoltaic material in solar cells.
Features and Benefits of the Product
High quality relative to competitors’ quantum dots
Low cost relative to competitors’ quantum dots
Market
Since quantum dots are used to make other products, Nano Assembly would be operating in the business-to-business market, although applications in fields like solar power also leave the door open for business-to-government sales.
Competitive Landscape
Current methods for producing quantum dots include high-temperature dual injection synthesis, molecular seeding, and a variation of the high-temperature dual injection method that incorporates a continuous flow system.
(Image courtesy of King Abdullah University of Science and Technology)
Credentials Dr. Pan has earned both a Bachelor of Science and Master of Science from Anhui Polytechnic University, along with a Ph.D. in Chemistry from the University of Science and Technology of China. He is now participating in a post-doctoral fellowship at KAUST. Within the Nano Assembly team, Dr. Pan is in charge of production.
El-Ballouli holds a Bachelor of Science in Chemistry and a Master of Science in Organic Chemistry from the American University of Beirut. She is currently a Ph.D. student at KAUST. Her primary area of interest is continuous-flow synthesis and size separation of quantum dots for assembly in solar cells. El-Ballouli is in charge of product testing for the team.
Dr. Bakr has earned a Bachelor of Science in Materials Science and Engineering from the Massachusetts Institute of Technology (MIT), as well as both a Master of Science and Ph.D. in Applied Physics from Harvard University. He is currently an Assistant Professor of Materials Science and Engineering, and Principal Investigator at KAUST. Dr. Bakr acts as scientific adviser to the Nano Assembly team.
Dr. Sargent holds a Bachelor of Science in Engineering Physics from Queen’s University, along with a Ph.D. in Electrical and Computer Engineering (Photonics) from the University of Toronto. He is the Vice Dean of Research for the Faculty of Applied Science & Engineering, a Professor in the Department of Electrical & Computer Engineering (ECE), and a KAUST Investigator. Dr. Sargent is the technique and business adviser for the team.
Timeline
Nano Assembly has already begun the process of incorporating their company. Their immediate task is to set up the production line that they have prepared, test it, and scale it up. They are expecting significant annual growth through 2017.
Big-Picture Impact on the Saudi Economy
The availability of high-quality quantum dots at a low price could help more tech-savvy companies and entrepreneurs enter the electronics, solar power, and medical imaging fields, among others. It could also help existing companies produce more cost-effective offerings within these fields. Either way, the end result would be a more technologically advanced and competitive Saudi Arabia.
Quantum dots, a technology with significant potential in optical applications and energy efficiency, is incredibly expensive and complicated to manufacture. This fact alone would be enough to keep this high potential technology out of industry use. In addition to such obstacles, conventional chemical synthesis of QDs must occur at high temperatures using toxic solvents, making waste removal a challenge. However, QDs can be used to advance medical imaging, light emitting diodes, and solar cells in commercial applications.
A process invented by Lehigh University Chemical Engineering professor Bryan Berger now allows for the manufacturing of quantum dots in a safer way and at a fraction of the cost. Whereas in conventional production techniques QDs could cost over $10,000 per gram, this manufacturing technique cuts that cost to about $1 per gram. Enabling a larger scale of production makes QDs a viable technology for use in commercial applications.
Learn more about Berger’s Facile, High Yield Synthesis and Purification of CdS Quantum Dots from Optimized Strains of S. Maltophelia on Lehigh’s Technology Publisher.
Quantum dots, a technology with significant potential in optical applications and energy efficiency, is incredibly expensive and complicated to manufacture. This fact alone would be enough to keep this high potential technology out of industry use. In addition to such obstacles, conventional chemical synthesis of QDs must occur at high temperatures using toxic solvents, making waste removal a challenge. However, QDs can be used to advance medical imaging, light emitting diodes, and solar cells in commercial applications.
A process invented by Lehigh University Chemical Engineering professor Bryan Berger now allows for the manufacturing of quantum dots in a safer way and at a fraction of the cost. Whereas in conventional production techniques QDs could cost over $10,000 per gram, this manufacturing technique cuts that cost to about $1 per gram. Enabling a larger scale of production makes QDs a viable technology for use in commercial applications.
Genesis Nanotechnologyo and l o 
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