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Big TV – Large Screen Makers are Forsaking OLED’s in Favor of Quantum Dots – Reuters October 30, 2014

Samsung Electronics' first curved, super-thin OLED television sets are displayed at the main office of the company in Seoul(Reuters) – The world’s biggest TV makers, Samsung Electronics Co Ltd and LG Electronics Inc, are turning to quantum dot technology for their next-generation TVs as it could still be years before OLED is affordable for the mass market.

 

The nascent technology involves incorporating a film of tiny light-emitting crystals into regular liquid crystal displays (LCD). The manufacturing process is relatively straightforward and offers improved picture quality at much cheaper cost than using organic light-emitting diodes (OLED).

The resulting lower prices could help the technology catch on far quicker. One industry analyst estimated a 55-inch quantum dot TV could be priced 30 to 35 percent more than a current LCD TV, while an OLED TV could be 5 times more expensive. LG recently launched a 65-inch ultra-high definition OLED TV for 12 million won ($11,350) in its home market of South Korea.

Samsung Electronics' first curved, super-thin OLED television sets are displayed at the main office of the company in Seoul

The only real challenge is securing enough quantum dot material from the small pool of suppliers, including Quantum Materials Corp and Nanoco Group PLC.

Nanoco last month said a South Korean plant being built by partner Dow Chemical Co will start quantum dot production in the first half of 2015. Analysts believe the output is destined for a local client.

On Wednesday, LG, the world’s No.2 TV maker after domestic rival Samsung, said it plans to make quantum dot TVs in addition to OLED TVs. Analysts regarded that a tacit acknowledgement that OLED needs more time for prices to come down before becoming the new standard.

“We are pursuing a dual-track strategy with quantum dot and OLED,” LG Chief Financial Officer Jung Do-hyun told analysts after the company reported earnings. OLED is the fundamentally superior product, he said.

Samsung Vice President Simon Sung told analysts on Thursday that quantum dot is among many technologies under consideration.

“How a technology will match with market conditions, when a technology will emerge as the main market segment is the most critical consideration,” Sung said. “We’ll respond aggressively after identifying such a market opportunity.”

At present, Japan’s Sony Corp is the only major electronics manufacturer selling quantum dot TVs. Last month, China’s TCL Multimedia Technology Holdings Ltd unveiled a quantum dot TV at the IFA tech expo in Berlin.

OLED RISK

LG and affiliate LG Display Co Ltd are the biggest champions of OLED TVs, in contrast to Samsung which has not released a model this year. Analysts say the lack of Samsung support could limit OLED growth prospects and keep prices high.

“In theory, OLED should become cheaper than LCD once production yields get better because OLED doesn’t need a backlight, but at this point both the scale and production yield remain low,” said CIMB analyst Lee Do-hoon.

“LG needs a product in the interim, and they seem to be saying they’ll look at market conditions and respond with quantum dot,” Lee said.

Samsung could be more aggressive than LG in pushing quantum dot as Korea’s No.1 consumer electronics maker appears less committed to a particular technology, analysts said. LG, on the other hand, risks undermining its OLED push.

“If LG focuses on quantum dot, it’d be basically the same as signaling that it will be difficult for OLED to go mainstream in the near term,” said CIMB’s Lee.

Researcher DisplaySearch forecasts 1.95 million quantum dot TV shipments next year, for just 0.8 percent of the market, growing to 25.5 million by 2020. IHS Technology sees OLED TV shipments at 7.8 million units by 2019 from 600,000 in 2015.

http://mobile.reuters.com/article/idUSKBN0IJ2LV20141030?irpc=932

Genesis Nanotech: Nanotechnology News & Updates  

1-water nano water-filter2Water Purification at the Molecular Level

Fracking for oil and gas is a dirty business. The process uses millions of gallons of water laced with chemicals and sand. Most of the contaminated water is trucked to treatment plants to be cleaned, which is costly and potentially environmentally hazardous. A Tufts engineer is researching how to create membranes for filters that may one day be able to purify the water right at a fracking site.

Water Purification at the Molecular Level: Research at Tufts University

1-rocket motor_news291014 Micro-Rockets with ‘Water-Fuel’ Neutralize Biological and Chemical Warfare With fears growing over chemical and biological weapons falling into the wrong hands, scientists are developing microrockets to fight back against these dangerous agents, should the need arise. In the journal ACS Nano, they describe new spherical micromotors that rapidly neutralize chemical and biological agents and use water as fuel.

Micro-Rockets with ‘Water’ Fuel to Neutralize Chemical & Biological Warfare

graphene-structureStart-Up Scales Graphene Production: Develops Bio-Sensors and Supercapacitors

An official of a materials technology and manufacturing startup says his company is addressing the challenge of scaling graphene production for commercial applications. Glenn Johnson, CEO of BlueVine Graphene Industries Inc., said many of the methodologies being utilized to produce graphene today are not easily scalable and require numerous post-processing steps to use it in functional applications. He said the company’s product development team has developed a way to scale the production of graphene to meet commercial volumes and many different applications.

Startup scales up graphene production, develops biosensors and supercapacitors

1-ACS Solar Band Gap nl-2014-03322a_0005Getting More Electricity Out of Solar Cells: MIT

New MIT model can guide design of solar cells that produce less waste heat, more useful current. When sunlight shines on today’s solar cells, much of the incoming energy is given off as waste heat rather than electrical current. In a few materials, however, extra energy produces extra electrons — behavior that could significantly increase solar-cell efficiency. An MIT team has now identified the mechanism by which that phenomenon happens, yielding new design guidelines for using those special materials to make high-efficiency solar cells.

Getting more electricity out of solar cells

1-google developGoogle Developing Nanotechnology to Detect Cancer and Heart Disease

Google Inc. revealed Tuesday at a conference in California that it is creating a wearable device and a pill with nanoparticles to detect certain developing diseases in the body, the Wall Street Journal reported.

Andrew Conrad, Google‘s head of the Life Sciences team at the Google X research lab, revealed that the company’s goal is to provide an early warning system for cancer and other diseases with a more efficient detection rate.

Google Developing Nanotechnology To Detect Cancer, Heart Disease

1-Graphene solar-panel-array-img_assist-400x301Graphene Solar Panels

Graphene is made of a single layer of carbon atoms that are bonded together in a repeating pattern of hexagons. It is a 2 dimensional material with amazing characteristics, which grant it the title “wonder material”. It is extremely strong and almost entirely transparent and also astonishingly conductive and flexible. Graphene is made of carbon, which is abundant, and can be a relatively inexpensive material. Graphene has a seemingly endless potential for improving existing products as well as inspiring new ones.

Graphene Solar Panels

Applications of Nanomaterials Chart Picture1Nano-Materials fro the Next Generation of Electronics and Photovoltaics: Controlling Size

One of the longstanding problems of working with nanomaterials—substances at the molecular and atomic scale—is controlling their size. When their size changes, their properties also change. This suggests that uniform control over size is critical in order to use them reliably as components in electronics.

Put another way, “if you don’t control size, you will have inhomogeneity in performance,” says Mark Hersam. “You don’t want some of your cell phones to work, and others not.”

Nano-Materials for the Next Generation of Electronics and Photovoltaics – Controlling Size

1-BC Water safe_imageNanotechnology: Can New Discoveries Help Us Provide Clean Water and Clean Renewable Energy?

Nanotechnology and Our Future Nanotechnology has been called “The Next Industrial Revolution.” It will or already has, impacted almost every facet of our daily lives. From ‘Nano-Enabled’ Solar Energy & Storage, Nano-Enabled Water Filtraion & Remediation to ‘Nano-Enabled’ Drug Therapies for Cancer, Alzheimers and DiabetesNanotechnology will serve to advance our technology capabilities to meet the Vision for a Better Quality of Life for all of us who share this Planet Earth as ‘Home’.

Nanotechnology: Can New Discoveries Help Us Provide Clean Water and Clean Renewable Energy?

*** Note to Readers and Supporters ***1-business-partnerships

Do you have or do you know of a ‘Special Water Project’ that is looking for Partners and/ or Support? If so, please contact us via our Website’s ‘Contact Form’ at:

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Thank You! Genesis Nanotechnology – “Great Things from

1-Heating and Cooling 141028114716-largeOctober 28, 2014

Source:
American Institute of Physics (AIP)
Summary:
If you’ve gone for a spin in a luxury car and felt your back being warmed or cooled by a seat-based climate control system, then you’ve likely experienced the benefits of a class of materials called thermoelectrics. Thermoelectric materials convert heat into electricity, and vice versa, and have many advantages over traditional heating and cooling systems. Recently, researchers have observed that the performance of some thermoelectric materials can be improved by combining different solid phases.

f you’ve ever gone for a spin in a luxury car and felt your back being warmed or cooled by a seat-based climate control system, then you’ve likely experienced the benefits of a class of materials called thermoelectrics. Thermoelectric materials convert heat into electricity, and vice versa, and they have many advantages over more traditional heating and cooling systems.

Recently, researchers have observed that the performance of some thermoelectric materials can be improved by combining different solid phases — more than one material intermixed like the clumps of fat and meat in a slice of salami. The observations offer the tantalizing prospect of significantly boosting thermoelectrics’ energy efficiency, but scientists still lack the tools to fully understand how the bulk properties arise out of combinations of solid phases.

 

1-Heating and Cooling 141028114716-large

 

Now a research team based at the California Institute of Technology (Caltech) has developed a new way to analyze the electrical properties of thermoelectrics that have two or more solid phases. The new technique could help researchers better understand multi-phase thermoelectric properties – and offer pointers on how to design new materials to get the best properties.

The team describes their new technique in a paper published in the journal Applied Physics Letters, from AIP Publishing.

An Old Theory Does a 180

Because it’s sometimes difficult to separately manufacture the pure components that make up multi-phase materials, researchers can’t always measure the pure phase properties directly. The Caltech team overcame this challenge by developing a way to calculate the electrical properties of individual phases while only experimenting directly with the composite.

“It’s like you’ve made chocolate chip cookies, and you want to know what the chocolate chips and the batter taste like by themselves, but you can’t, because every bite you take has both chocolate chips and batter,” said Jeff Snyder, a researcher at Caltech who specializes in thermoelectric materials and devices.

To separate the “chips” and “batter” without un-baking the cookie, Snyder and his colleagues turned to a decades old theory, called effective medium theory, and they gave it a new twist.

“Effective medium theory is pretty old,” said Tristan Day, a graduate student in Snyder’s Caltech laboratory and first author on the APL paper. The theory is traditionally used to predict the properties of a bulk composite based on the properties of the individual phases. “What’s new about what we did is we took a composite, and then backed-out the properties of each constituent phase,” said Day.

The key to making the reversal work lies in the different way that each part of a composite thermoelectric material responds to a magnetic field. By measuring certain electrical properties over a range of different magnetic field strengths, the researchers were able to tease apart the influence of the two different phases.

The team tested their method on the widely studied thermoelectric Cu1.97Ag0.03Se, which consists of a main crystal structure of Cu2Se and an impurity phase with the crystal structure of CuAgSe.

Temperature Control of the Future?

Thermoelectric materials are currently used in many niche applications, including air-conditioned car seats, wine coolers, and medical refrigerators used to store temperature-sensitive medicines.

“The definite benefits of using thermoelectrics are that there are no moving parts in the cooling mechanism, and you don’t have to have the same temperature fluctuations typical of a compressor-based refrigerator that turns on every half hour, rattles a bit and then turns off,” said Snyder.

One of the drawbacks of the thermoelectric cooling systems, however, is their energy consumption.

If used in the same manner as a compressor-based cooling system, most commercial thermoelectrics would require approximately 3 times more energy to deliver the same cooling power. Theoretical analysis suggests the energy efficiency of thermoelectrics could be significantly improved if the right material combinations and structures were found, and this is one area where Synder and his colleagues’ new calculation methods may help.

Many of the performance benefits of multi-phase thermoelectrics may come from quantum effects generated by micro- and nano-scale structures. The Caltech researchers’ calculations make classical assumptions, but Snyder notes that discrepancies between the calculations and observed properties could confirm nanoscale effects.

Snyder also points out that while thermo-electrics may be less energy efficient than compressors, their small size and versatility mean they could be used in smarter ways to cut energy consumption. For example, thermoelectric-based heaters or coolers could be placed in strategic areas around a car, such as the seat and steering wheel. The thermoelectric systems would create the feeling of warmth or coolness for the driver without consuming the energy to change the temperature of the entire cabin.

“I don’t know about you, but when I’m uncomfortable in a car it’s because I’m sitting on a hot seat and my backside is hot,” said Snyder. “In principle, 100 watts of cooling on a car seat could replace 1000 watts in the cabin.”

Ultimately, the team would like to use their new knowledge of thermoelectrics to custom design ‘smart’ materials with the right properties for any particular application.

“We have a lot of fun because we think of ourselves as material engineers with the periodic table and microstructures as our playgrounds,” Snyder said.


Story Source:

The above story is based on materials provided by American Institute of Physics (AIP). Note: Materials may be edited for content and length.

1-SelfAssemblyAPS1Techniques for creating complex nanostructured materials through self-assembly of molecules have grown increasingly sophisticated. But carrying these techniques to the biological realm has been problematic. Recently, scientists from Northwestern University used self-assembly under controlled conditions to create a membrane consisting of layers with distinctly different structures.

 

 

Now, working at the U.S. Department of Energy’s Advanced Photon Source (APS), the team utilized small-angle x-ray scattering (SAXS) to better determine these structures and study how they form. This new information paves the way for design and synthesis of hierarchical structures with biomedical applications.

Peptide amphiphiles (PA) are chains of amino acids tipped with other molecules so that one end is hydrophilic (mixes well with water) and the other hydrophobic (not fond of water). In aqueous solution, PAs form long, thin nanofibers as the amino acid chains bind to adjacent chains to form β–sheets. The Northwestern University scientists had previously found that when an aqueous solution containing positively-charged PAs was put into contact with an aqueous solution of negatively charged hyaluronic acid (HA—a large biological molecule that occurs in connective and other tissues), a dense, fibrous layer formed within milliseconds, creating a barrier that kept the two solutions from mixing.

1-SelfAssemblyAPS1

More precisely, the researchers found that the fibrous layer prevents aggregated PAs from migrating to the HA side, but allows HA molecules to slowly insinuate themselves through the barrier to the PA side, on a timescale of minutes or longer.

The result was a three-zone membrane structure: a gel-like layer on the HA side, a fibrous mat consisting of PA nanofibers lying in the plane of the interface between the solutions, and a coating of fibers directed perpendicularly away from the interface and formed by electrostatically bound complexes of PA and HA (Image 1).

The team’s interest in these membranes hinged on possible biomedical uses in which the peptide sequence forming the nanofibers would have a chosen biological activity. In one example, they incorporated a heparin-binding sequence to promote angiogenesis (the formation of new blood vessels), so that the membrane might assist with tissue repair. For the three-zone structure to form, the researchers found that the HA solution had to contain heparin in a certain concentration range. Scanning electron microscopy clearly showed linear structure crossing the membrane that formed when heparin was present at 0.5% by weight (Image 2a), in contrast to the more homogeneous appearance of the membrane created in the absence of heparin (Image 2b).

Scanning electron micrographs show the homogeneous membrane that forms in the absence of heparin (A), while in the presence of heparin is a fibrous structure forms transverse to the membrane (B).Scanning electron micrographs show the homogeneous membrane that forms in the absence of heparin (A), while in the presence of heparin is a fibrous structure forms transverse to the membrane (B).The scientists turned to SAXS at the DuPont-Northwestern-Dow Collaborative Access Team beamline 5-ID-D at the Argonne APS, an Office of Science user facility. These studies yield insight into the precise structure of the three-zone membranes and a better understanding of the dynamics of their formation.

The heparin-free membranes produced well-defined Bragg peaks, while the three-zone membranes did not. Moreover, membranes that arose in the presence of smaller heparin concentrations showed larger Bragg peaks than those produced when the heparin concentration was higher, indicating a competition between two structures whose outcome depended on heparin levels.

A time-series of SAXS measurements on a heparin-free experiment showed that the Bragg peaks began to form a few minutes after the two solutions were brought into contact, and reached full strength after about 45 minutes.

Interpreting the SAXS findings in the light of their previous experiments and the known properties of PAs and HA, the scientists explain the differences between the two types of membrane as the result of different kinds of aggregation. In the absence of heparin, the PA and HA come together in nanospherical aggregates that pack together in a cubic arrangement, over a period of some tens of minutes, to form a membrane that generates well-defined Bragg peaks.

When heparin is present, by contrast, it binds strongly with the PA and alters its interaction with AH molecules. In this case, a barrier of nanofibers lying parallel to the solution interface forms immediately, then acts as a diffusion barrier through which HA slowly passes. As it emerges on the other side, it binds to PA to form nanofibers that grow perpendicular to the interface. This ordered nanofiber array produces no Bragg peaks.

The increased understanding and control of these processes derived from this research could make it possible to build bioactive membranes with a variety of structures and purposes.

Electrostatic Control of Structure in Self-Assembled Membranes

Source: Argonne National Laboratory

 

This video shows the manual stretching of a single 5 µm-arm silicon spiral for 8 cycles, which demonstrates mechanical robustness and reliability. (Video: Integrated Nanotechnology Laboratory, KAUST)

 

1-KAUST 04d5b1fProf. Muhammad Mustafa Hussain, Associate Professor of Electrical Engineering at KAUST, and his group, have developed an innovative type of ultra-stretchable silicon (up to 10 times its original length) for flexible electronics. This “smart skin” represents and important advance in the future development of foldable electronics and photovoltaics.

The flexibility required when fabricating flexible electronic components has led to the use of plastic substrates, carbon nanomaterials, and different transfer techniques to fabricate flexible devices. One of the biggest obstacles to mass adoption of flexible electronics has been the incompatibility of most of these solutions with industry’s state-of-the-art silicon-based CMOS processes – which still produce about 90% of today’s electronics. Researchers have now demonstrated ultra-stretchability in monolithic single-crystal silicon. The design is based on an all silicon-based network of hexagonal islands connected through spiral springs. “With this structure, we have been able to achieve a remarkable stretch ratio of about 1000% using a brittle material such as silicon,” Muhammad Mustafa Hussain, an Associate Professor of Electrical Engineering at King Abdullah University of Science and Technology (KAUST), tells Nanowerk. Hussain and his team have published their findings in Applied Physics Letters (“Design and characterization of ultra-stretchable monolithic silicon fabric”). The fabrication process is based on conventional microfabrication techniques consisting on five basic steps: Starting with a silicon-on-insulator wafer (50 µm), 1) a gold hard mask is first deposited on silicon-on-insulator and then patterned using 2) photolithography and 3) reactive ion etching (RIE). Next, 4) the silicon is deeply, anisotropically etched (DRIE) until the buried oxide layer is reached and then the hard mask is removed. Finally, 5) the silicon structure is release with vapor hydrofluoric acid, which removes the underlying oxide layer.

 

microfabrication process for stretchable siliconSummarized fabrication process flow with digital photographs of final designs. (a) Hard mask deposition. (b) Photolithography step. (c) Hard mask’s patterning. (d) Silicon DRIE and hard mask removal. (e) Release of silicon structures with VHF. (f) Digital photographs and zoom-ins of an array of 800 µm-side-hexagons interconnected by single 5 µm-arm spirals (scale bar is 2mm long, 1mm for the first zoom-in and 0.5mm for the spiral zoom-in). (g) Digital photographs and zoom-ins of an array of 800 µm-sidehexagons interconnected by double 2 µm-arm spirals (scale bar is 2mm long, 0.5mm for the first zoom-in and 0.2mm for the spiral zoom-in). (© AIP) Hussain points out that device implementation can be achieved through CMOS-compatible fabrication previous to the 5-step release process described above. The resulting single-spiral structures can be stretched to a ratio more than 1000%, while remaining below a 1.2% strain. Moreover, these network structures have demonstrated area expansions as high as 30 folds in arrays.

“While handling still remains a challenge, our method can provide ultra-stretchable and adaptable electronic systems for distributed network of high-performance macro-electronics especially useful for wearable electronics and bio-integrated devices,” says Hussain. The researchers are currently working to demonstrate electronic devices implemented on top of their hexagon islands and interconnected through the spiral springs to form stretchable sensor networks with outstanding electrical performance and mechanical robustness.

 

Since the battery is still in prototype phase, last month Graphene 3D Labs announced a partnership with Stony Brook University in Long Island, NY, for a round of quality control testing to get it to the next step.

Graphene 3D Labs recently introduced their 3D printed graphene battery prototype in the Inside 3D Printing Conference in Santa Clara, California. The prototype battery is composed of nanoplatelets of graphene that are added to polymers, and can already produce the same amount of energy as a common AA battery. The company states that these batteries will be able to be integrated into a 3D-printed object while that object is still being built, which grants the batteries enhanced performance potential (compared to non-integrated batteries) due to precise customization.

 

Graphene 3D Lab is a joint-venture between Graphene Labs and Lomiko Metals. The company focuses on the development of high-performance graphene-enhanced materials for 3D Printing. Graphene 3D Lab trades in the Canadian stock exchange (TSX:GGG), and we recently posted an interview with the company’s founder and COO.

Back in May 2013, Lomiko Metals, SBUY and Graphene Labs signed an agreement to investigate graphene based applications – mainly supercapacitors and batteries.

 

 

 

 

 

Battery basics

1-Graphene Eneloop-battery-design-img_assist-300x290Batteries serve as a mobile source of power, allowing electricity-operated devices to work without being directly plugged into an outlet. While many types of batteries exist, the basic concept by which they function remains similar: one or more electrochemical cells convert stored chemical energy into electrical energy. A battery is usually made of a metal or plastic casing, containing a positive terminal (a cathode), a negative terminal (an anode) and electrolytes that allow ions to move between them. A separator (a permeable polymeric membrane) creates a barrier between the anode and cathode to prevent electrical short circuits while also allowing the transport of ionic charge carriers that are needed to close the circuit during the passage of current. Finally, a collector is used to conduct the charge outside the battery, through the connected device.

When the circuit between the two terminals is completed, the battery produces electricity through a series of reactions. The anode experiences an oxidation reaction in which two or more ions from the electrolyte combine with the anode to produce a compound, releasing electrons. At the same time, the cathode goes through a reduction reaction in which the cathode substance, ions and free electrons combine into compounds. Simply put, the anode reaction produces electrons while the reaction in the cathode absorbs them and from that process electricity is produced. The battery will continue to produce electricity until electrodes run out of necessary substance for creation of reactions.

1-Graphene Eneloop-battery-design-img_assist-300x290

Battery types and characteristics

Batteries are divided into two main types: primary and secondary. Primary batteries (disposable), are used once and rendered useless as the electrode materials in them irreversibly change during charging. Common examples are the zinc-carbon battery as well as the alkaline battery used in toys, flashlights and a multitude of portable devices. Secondary batteries (rechargeable), can be discharged and recharged multiple times as the original composition of the electrodes is able to regain functionality. Examples include lead-acid batteries used in vehicles and lithium-ion batteries used for portable electronics.

Batteries come in various shapes and sizes for countless different purposes. Different kinds of batteries display varied advantages and disadvantages. Nickel-Cadmium (NiCd) batteries are relatively low in energy density and are used where long life, high discharge rate and economical price are key. They can be found in video cameras and power tools, among other uses. NiCd batteries contain toxic metals and are environmentally unfriendly. Nickel-Metal hydride batteries have a higher energy density than NiCd ones, but also a shorter cycle-life. Applications include mobile phones and laptops. Lead-Acid batteries are heavy and play an important role in large power applications, where weight is not of the essence but economic price is. They are prevalent in uses like hospital equipment and emergency lighting.

Lithium-Ion (Li-ion) batteries are used where high-energy and minimal weight are important, but the technology is fragile and a protection circuit is required to assure safety. Applications include cell phones and various kinds of computers. Lithium Ion Polymer (Li-ion polymer) batteries are mostly found in mobile phones. They are lightweight and enjoy a slimmer form than that of Li-ion batteries. They are also usually safer and have longer lives.  However, they seem to be less prevalent since Li-ion batteries are cheaper to manufacture and have higher energy density.

Graphene and batteries

Graphene, a sheet of carbon atoms bound together in a honeycomb lattice pattern, is hugely recognized as a “wonder material” due to the myriad of astonishing attributes it holds. It is a potent conductor of electrical and thermal energy, extremely lightweight chemically inert, and flexible with a large surface area. It is also considered eco-friendly and sustainable, with unlimited possibilities for numerous applications.

graphene-structure

In the field of batteries, conventional battery electrode materials (and prospective ones) are significantly improved when enhanced with graphene. Graphene can make batteries light, durable and suitable for high capacity energy storage, as well as shorten charging times. It will extend the battery’s life-time, which is negatively linked to the amount of carbon that is coated on the material or added to electrodes to achieve conductivity, and graphene adds conductivity without requiring the amounts of carbon that are used in conventional batteries.

Graphene can improve such battery attributes as energy density and form in various ways. Li-ion batteries can be enhanced by introducing graphene to the battery’s anode and capitalizing on the material’s conductivity and large surface area traits to achieve morphological optimization and performance.

It has also been discovered that creating hybrid materials can also be useful for achieving battery enhancement. A hybrid of Vanadium Oxide (VO2) and graphene, for example, can be used on Li-ion cathodes and grant quick charge and discharge as well as large charge cycle durability. In this case, VO2 offers high energy capacity but poor electrical conductivity, which can be solved by using graphene as a sort of a structural “backbone” on which to attach VO2 – creating a hybrid material that has both heightened capacity and excellent conductivity.

Another example is LFP ( Lithium Iron Phosphate) batteries, that is a kind of rechargeable Li-ion battery. It has a lower energy density than other Li-ion batteries but a higher power density (an indicator of of the rate at which energy can be supplied by the battery). Enhancing LFP cathodes with graphene allowed the batteries to be lightweight, charge much faster than Li-ion batteries and have a greater capacity than conventional LFP batteries.

In addition to revolutionizing the battery market, combined use of graphene batteries and supercapacitors could yield amazing results, like the noted concept of improving the electric car’s driving range and efficiency.

Batteries and Supercapacitors

While there are certain types of batteries that are able to store a large amount of energy, they are very large, heavy and release energy slowly. Capacitors, on the other hand, are able to charge and discharge quickly but hold much less energy than a battery. The use of graphene in this area, though, presents exciting new possibilities for energy storage, with high charge and discharge rates and even economical affordability. Graphene-improved performance thereby blurs the conventional line of distinction between supercapacitors and batteries.

Li-Polymer-battery-vs-supercapacitor-img_assist-400x229

Commercial Graphene-enhanced Battery Products

In June 2014, US based Vorbeck Materials announced the Vor-Power strap, a lightweight flexible power source that can be attached to any existing bag strap to enable a mobile charging station (via 2 USB and one micro USB ports). the product weighs 450 grams, provides 7,200 mAh and is probably the world’s first graphene-enhanced battery.

Vorbeck-vor-power-img_assist-400x217

In May 2014, American company Angstron Materials rolled out several new graphene products. The products, said to become available roughly around the end of 2014, include a line of graphene-enhanced anode materials for Lithium-ion batteries. The battery materials were named “NANO GCA” and are supposed to result in a high capacity anode, capable of supporting hundreds of charge/discharge cycles by combining high capacity silicon with mechanically reinforcing and conductive graphene.

Developments are also made in the field of graphene batteries for electric vehicles, such as Graphene Nanochem and Sync R&D’s October 2014 plan to co-develop graphene-enhanced Li-ion batteries for electric buses, under the Electric Bus 1 Malaysia program. In August 2014, Tesla suggested the development of a “new battery technology” that will almost double the capacity for their Model S electric car. It is unofficial but reasonable to assume graphene involvement in this battery. UK based Perpetuus Carbon Group and OXIS Energy agreed in June 2014 to co-develop graphene-based electrodes for Lithium-Sulphur batteries, which will offer improved energy density and possibly enable electric cars to drive a much longer distance on a single battery charge.

Another interesting venture, announced in September 2014 by US based Graphene 3D Labs, regards plans to print 3D graphene batteries. These graphene-based batteries can potentially outperform current commercial batteries as well as be tailored to various shapes and sizes.

Other prominent companies which declared intentions to develop and commercialize graphene-enhanced battery products are: Grafoid, SiNode together with AZ Electronic Materials, XG Sciences, Graphene Batteries together with CVD Equipment and CalBattery.

Exciting research in the field of Graphene Batteries

The field of graphene-enhanced batteries is brimming with activity and research, striving to develop and improve materials. One example of such research is the development of better performing and cheaper Li-ion batteries made by researchers from the University of Southern California in April 2014. The anode was made from silicon and the cathode was made of sulfur powder coated with graphene oxide. Another example is Wuhan University of Technology’s development of a new graphene-based high-energy electrode for Li-ion batteries in August 2014, using a 3D-crumpled graphene that encapsulates Nickel-Sulfide.

The Korean KAIST institute developed in August 2014 a new method of fabricating defect-free graphene. This enabled them to develop a promising high-performance anode for Li-ion batteries. Also in August 2014, researchers from Rice University developed a new chemical process that can be used to create a tough, ultra-light foam (called GO-0.5BN) that is made from two 2D ,materials: graphene oxide and hexagonal boron nitride (hBN) platelets. This foam can serve as a structural component in applications such as electrodes for batteries, supercapacitors and gas absorption material.

In April 2014, researchers from the University of Southern California developed better performing and cheaper Li-ion batteries. The anode in these batteries is made from Silicon (and is said to be three times more powerful and longer lasting compared to conventional graphite anodes). The cathode is made of sulfur powder coated with graphene oxide. the GO coating seems to solve sulfur’s poor conductivity and cyclability issues, resulting in newly developed cathodes that offer 5 times the capacity of commercial ones.

“Graphene … The Wonder Material!”

Further reading

1-Transparent diet(Phys.org) —All objects’ colors are determined by the way that light scatters off of them. By manipulating the light scattering, scientists can control the wavelengths at which light is transmitted and reflected by objects, changing their appearance.

 

 

In a new study published in Physical Review Letters, researchers have developed a new method for manipulating . They theoretically show how to induce in otherwise opaque materials using the complex dipole-dipole interactions present in a large number of interacting quantum emitters, such as atoms or molecules. This ability could have several potential , such as producing slow or stopped light, along with applications in the field of attosecond physics.

“The significance of our work is in the discovery of a very neat phenomenon (dipole-induced electromagnetic transparency [DIET]), which may be used to control light propagation in optically active media,” coauthor Eric Charron, Professor at the University of Paris-Sud in Orsay, France, told Phys.org. “We showed how light scattering by a nanometric size system, collectively responding through strongly coupled two-level atoms/molecules, can be manipulated by altering the material parameters: an otherwise opaque medium can be rendered transparent at any given frequency, by adequately adjusting the relative densities of the atoms/molecules composing it.”

As the scientists explain, light scattering is very well understood when dealing with individual quantum emitters; that is, single atoms or molecules. But the physics becomes much more complex when dealing with two or more interacting emitters. In this case, the electromagnetic field experienced by an emitter depends not only on the light beam striking its surface, but also on all of the electromagnetic fields radiated by all of its neighbors, which in turn are affected by the emitter in question.

1-Transparent diet

Illustration of a thin, dense vapor of quantum emitters (blue disk) interacting with an incident electromagnetic field. Physicists have shown that strong dipole-dipole interactions in the quantum emitters can be used to manipulate the light …more

Each quantum emitter can have a dipole, meaning a positive side and a negative side, due to an uneven distribution of electrons within the emitter. In a dense “vapor” of many quantum emitters, strong dipole-dipole couplings can then occur. The collective effects usually result in an enhancement of the light-matter interaction, although a very complicated one.

 Here, the researchers have theoretically shown that strong dipole-dipole interactions in a dense vapor of quantum emitters can be used to manipulate the spectral properties of the light scattered by the emitters. In particular, the medium may become transparent at a particular frequency that can be controlled to a certain extent.

The scientists explain that, on the most basic level, DIET results from destructive interference between the electromagnetic waves emitted by the quantum emitters. DIET is also closely related to another phenomenon, called electromagnetically-induced transparency (EIT). EIT is also based on destructive interference, but it is induced by a laser instead of dipole-dipole interactions.

The scientists expect that DIET could have many of the same applications as EIT, which include the generation of slow light or stopped light by interactions with the medium. Slow light has a variety of optical applications, including information transmission, switches, and high-resolution spectrometers. Also, in the field of attosecond physics, DIET could potentially be used to generate high harmonics in dense atomic or molecular gases.

The researchers anticipate that DIET can be experimentally implemented in a few different ways, including in atomic vapor confined in a cell as well as in ultracold dense atomic clouds. However, both systems still face challenges for demonstrating DIET, which must be addressed in the future.

“Currently our goal is to hunt for the observation of DIET in multilevel atomic or molecular systems,” Charron said. “Each emitter will behave as a series of oscillating dipoles, and this is expected to yield a series of transparency windows, thus opening the way for more elaborate and flexible manipulation strategies. We will publish new results on this topic in Arxiv in the next few weeks. Moreover, DIET offers yet another way to slow the light due to strong anomalous dispersion. We thus plan to develop the study of slow light with DIET in the near future, with potential applications for information processing.”

Explore further: Quantum holograms as atomic scale memory keepsake

 

2-atomicstruct(Phys.org) —Scientists have long observed that the wettability of graphene – an essentially two-dimensional crystalline allotrope of carbon that it interacts oddly with light and with other materials – can be reversed between hydrophobic and hydrophilic states by applying ultraviolet (UV) irradiation. However, an explanation for this behavior has remained elusive.

 

Recently, researchers at The University of New South Wales and University of Technology, Sydney investigating this phenomenon both experimentally and by calculations using density functional theory (DFT) – a computational quantum mechanical modeling method – finding that UV irradiation enables this reversible and controllable transition in graphene films having induced defects by water splitting adsorption on the graphene surface of H2O molecules in air. (Water splitting is the chemically dissociative reaction in which water is separated into hydroxyl and hydrogen; hydroxyl is a chemical functional group containing an oxygen atom connected by a covalent bond to a hydrogen atom; and adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface.)

The scientists conclude that their discovery may provide new insights into the fundamental principles of with -based materials, and could thereby lead to other applications – including electrocatalysis, nanomaterials; nanoelectromechanical systems, biomaterials, microfluidic devices, hybrid organic systems, and other advanced multifunctional systems.

Dr. Zhimin Ao discussed the paper that he, Doctoral Student Zhemi Xu and their co-authors published in Scientific Reports and the main challenges the researchers faced. “The main challenge – and the motivation for the conducting the study – was to reveal the real mechanism of the reversible wettability transition under UV irradiation and isolate it from various possible reasons, such as the contamination of chemicals on samples or induced by molecules in air,” Ao tells Phys.org. “We also had to identify H2O rather than other possible molecules in air, which contributes the wettability transition under UV irradiation.” After determining the contribution of H2O, he adds, another challenge was to understand the adsorption type of H2O for the wettability transition – that is, chemical or physical adsorption.

“Secondly,” Ao continues, “to eliminate drawbacks from chemical doping and induced defects – such as organic molecules on the graphene sample – that may be an important factor in graphene’s wettability transition under UV, the samples were stored for two hours in a vacuum to remove contaminants on the graphene surface.” As a result, most of the remaining graphene defects, such as vacancies, edges and grain boundary, would be there due to the synthesis process.

“According to our calculations, on defects of vacancies, edge and grain boundary, water splitting can be easier to achieve. However, other defects can also affect the wettability of graphene, such as aluminum doping, which has been reported by another paper1 of my group.”

 

The reaction pathways for the dissociative adsorption of an H2O and an O2 molecule on graphene. Pristine graphene (a) and (b); graphene with mono-atom vacancy (c) and (d); divacancy (e) and (f); edge (g) and (h); grain boundary (i) and (j). …more

The key technique the researchers used to address these challenges was to combine experiment and first-principles calculations. “In our experiment, we demonstrated that the wettability of graphene could be reversibly tuned through UV irradiation in air and vacuum storage,” Ao says. “In addition, computational calculations enable us to understand the exact effect of each individual factor.” After comparing their experimental and calculation results, the scientists found that Raman spectra from the experiment were similar to that of H2O dissociative adsorption on graphene. (In graphene research, Raman spectroscopy is used to determine the number and orientation of layers, the quality and types of edge, and the effects of perturbations, such as electric and magnetic fields, strain, and doping.)

Moreover, they also considered irradiations at different conditions, such as in O2 and H2O rich environments, and found that H2O concentration clearly affected the wettability change of graphene after irradiation. “Therefore,” Ao adds, “we concluded that H2O dissociative adsorption on graphene induces the reversible wettability transition.”

The direct application for this approach is water splitting – a very important step in, for example, hydrogen generation: Using the technique in this work, H2O molecules could be easily split into OH and H+ groups and adsorbed on defect-induced graphene under UV irradiation. After irradiation, the two groups can be easily desorbed from the graphene and produce hydrogen, allowing the graphene to be used continually as a catalyst for water splitting.

Ao points out that when fabricating devices based on graphenefor example, solar cells – layer-by-layer materials fabrication is required. “Hydrophilic graphene is more easily modified and combined with other materials than is hydrophobic graphene. For example, in the case of biomaterials, hydrophilic graphene would be desirable for the biomolecule contact.”

It turns out that achieving graphene reversible wettability can be accomplished using other techniques, including external electric fields, plasma treatment, magnetic fields, and neutron diffraction. “Actually, the work with achieving graphene reversible wettability using external electric fields was also reported2 by my group based on first-principle calculations. Compared with using external electric fields, UV irradiation is easily realized in experiment, while a very high electric field is required to realize the wettability transition,” noting that an experiment under strong electric field is underway. “Plasma has even greater energy, and may induce more defects in graphene. However, the plasma treatment process is more complicated and has higher greater requirements.”

 

Calculated Raman spectra of graphene. (a) With water, and (b) with oxygen dissociatively adsorbed. Credit: Xu, Z. et al. Reversible Hydrophobic to Hydrophilic Transition in Graphene via Water Splitting Induced by UV Irradiation. Sci. Rep. 4, 6450.

Looking ahead, Ao notes that they need to further clarify the mechanism for graphene’s hydrophobic to hydrophilic transition under UV irradiation because the latter itself can induce graphene defects. “Although UV irradiation was believed to induce defects in graphene, the problem is that these defects aren’t obvious because this energy source is not strong enough. To further clarify the reversible wettability mechanism, we may use different energy sources to investigate the transition, such as X-ray and neutron diffraction.” They also plan to investigate conductivity change and transport properties under UV irradiation.

“High electrical conductivity graphene film with high hydrophilicity is always desirable,” Ao tells Phys.org. “However, these two properties are normally resisting each other. When working with graphene-based devices, exploring the electric conductivity variation of graphene in such processes can help to control and balance these two properties.”

Other areas that might benefit from their study, Ao concludes, include sensors and hydrogen generation and storage.

Explore further: On the edge of grapheme

 

Published on October 25, 2014 at 9:30 AM

A University of Houston researcher is trying a novel approach to create high efficiency, low cost solar cells in an effort to bring the cost down to that of traditional electricity sources.

The picture above shows: (a) epitaxial gallium-arsenide thin film on flexible metal foil, and (b) schematic of the multilayer architecture developed in this work to grow epitaxial gallium-arsenide thin film on metal foil. Credit: University of Houston

Venkat Selvamanickam, M.D. Anderson Chair professor of mechanical engineering and director of the Applied Research Hub at the Texas Center for Superconductivity at UH, received a $1,499,994 grant from the U.S. Department of Energy SunShot Initiative to produce high efficiency, inexpensive thin film photovoltaics.

The grant is part of the department’s SunShot Initiative, created in 2011 to make solar energy cost-competitive with other forms of electricity by the end of the decade. Since then, it has funded more than 350 projects, with a goal of bringing the cost of solar electricity to about $0.06 per kilowatt-hour.

Selvamanickam, whose lab already produces thin film superconducting wire, said he began thinking several years ago about developing a technique to produce solar cells using a technique similar to the one he uses for coating semiconductors as thin films on low-cost metal substrates, based on a similar roll-to-roll manufacturing technology.

The solar cells targeted by Selvamanickam are different from the solar panels people are accustomed to seeing on rooftops. Solar cells traditionally are produced on silicon wafers, while the most efficient solar cells are composed of a germanium wafer, topped with gallium-arsenide.

But that type of solar cell is expensive, Selvamanickam said, both because of the high costs of the germanium wafer and the manufacturing process. And the germanium wafers are small, requiring a large number to cover much area. Consequently, they are used mainly for space applications.

His process involves using a metal foil tape with a germanium thin film – although he said another substance could be used as a base – and moving it at high speed with the roll-to-roll technology, coating it in a vacuum chamber with vapors of gallium and arsine.

The work is being done in Selvamanickam’s Energy Devices Fabrication Laboratory at the UH Energy Research Park. The Energy Research Park was established by the University in 2010 to conduct translational research to rapidly develop and transfer new technologies to industry. The new project with SunShot will be conducted in collaboration with the South Dakota School of Mines and Technology.

Selvamanickam said his team presented proof-of-concept with his application to the Energy Department, showing high-quality gallium arsenide thin films on metal foils. Those results were published in the journal Applied Physics Letters in September.

Other researchers have used roll-to-roll manufacturing technology for solar cells but not with the germanium-gallium-arsenide materials and so they had much lower efficiency, he said.

Single-junction solar cells on germanium wafers produced with gallium-arsenide can operate at an efficiency of 28.5 percent, with a cost of several dollars per watt. Selvamanickam’s goal is to produce a solar cell that operates at 24 percent efficiency at a cost of 20 cents per watt.

Source: http://www.uh.edu/


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