“At the Speed of Light” – New ‘Nanowires’ Support Integrated Nanophotonic Circuits


Nanowires 149_thumbnail_100A new combination of materials can efficiently guide electricity and light along the same tiny wire, a finding that could be a step towards building computer chips capable of transporting digital information at the speed of light.

Abstract

The continually increasing demands for higher-speed and lower-operating-power devices have resulted in the continued impetus to shrink photonic components. We demonstrate a primitive nanophotonic integrated circuit element composed of a single silver nanowire and single-layer molybdenum disulfide (MoS2 ) flake.

Using scanning confocal fluorescence microscopy and spectroscopy, we find that nanowire plasmons can excite MoS2 photoluminescence and that MoS2 excitons can decay into nanowire plasmons. Finally, we show that the nanowire may serve the dual purpose of both exciting MoS2 photoluminescence via plasmons and recollecting the decaying exciton as nanowire plasmons. The potential for subwavelength light guiding and strong nanoscale light–matter interaction afforded by our device may facilitate compact and efficient on-chip optical processing.

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© 2014 Optical Society of America

Funding By: Directorate for Mathematical and Physical Sciences (MPS)10.13039/100000086 (DMR-1309734); Office of Science, U.S. Department of Energy10.13039/100006132 (DE-FG02-05ER46207); NSF IGERT (DGE-0966089); Institute of Optics.

To read the Full Disclosure Paper Go Here:

http://www.opticsinfobase.org/optica/fulltext.cfm?uri=optica-1-3-149&id=300737

 

Nanowires 3 getImage

 

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Dateline Australia: World’s First Technology Breakthrough In Using Graphene For Micro Devices


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Next month, Dr. Iacopi will travel to Seattle in the US to address the 4th International Symposium on Graphene Devices.

 

 

 

 

Dr. Francesca Iacopi

Researchers are claiming world-first technology developed at Griffith University will harness the remarkable properties of graphene and could launch the next generation of mass produced, low-cost micro-devices.

Dr. Francesca Iacopi’s novel micro-fabrication process enables production-scale manufacturing of a material companies can use to commercially produce sensor devices which are biocompatible, chemically resistant and highly sensitive.

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“We believe this process will change the way we live by providing the ultimate in device miniaturisation,” says Dr Iacopi, from Griffith University’s Queensland Micro- and Nanotechnology Centre.

“It will influence a lot of different sectors because many modern applications relying on micro and nano-devices will be able to advance by incorporating this technology,” says Dr Iacopi, from Griffith University’s Queensland Micro and Nanotechnology Centre.

“For example, medicine is just one area where this technology can be applied. Someone with diabetes could have a nanochip sitting on their skin -– mass produced with the help of our micro-fabrication process — continuously monitoring their blood, and any changes can be relayed directly to a doctor.”

First isolated in the laboratory about a decade ago, graphene is pure carbon and one of the thinnest, lightest and strongest materials known.

A supreme conductor of electricity and heat, much has been written about its mechanical, electrical, thermal and optical properties and the possibilities with the fabrication of new and advanced micro-devices.

However, progress so far has been slow due to the difficulty in synthesising high quality graphene on to Silicon wafers, which would enable cost-effective mass production of such devices.

That problem has now been overcome.

Working with three PhDs, a postdoctorate, national and international collaborators Dr Iacopi has developed:

  • a low temperature process to synthesise graphene by using a metal alloy catalyst which produces a continuous, high quality, controllable graphene film;
  • a strategy for patterning graphene in such a way that it will grow only on a pre-patterned Silicon Carbide (SiC) layer on Silicon.

“Until now, high quality graphene was restricted to the use of expensive SiC wafers or the use of complicated transfer procedures to Silicon wafers. A cheaper substrate and a simpler methodology was badly needed to ensure the micro-devices would be cost-competitive,” says Dr Iacopi.

“At Griffith, we were the first develop a method for depositing a very high quality thin layer of SiC on to 300mm Si wafers.

“This work is still very early but the prospects are very exciting and broad-ranging.”

Dr Iacopi and her team have already begun seeking industry partners to leverage the technology in an industrial product.

 

Perovskite: New Wonder Material to make Cheaper & Easier to Manufacture LED’s


 

 

ledsmadefromColourful LEDs made from a material known as perovskite could lead to LED displays which are both cheaper and easier to manufacture in future. 

A hybrid form of perovskite – the same type of material which has recently been found to make highly efficient solar cells that could one day replace silicon – has been used to make low-cost, easily manufactured LEDs, potentially opening up a wide range of in future, such as flexible colour displays.

This particular class of semiconducting perovskites have generated excitement in the solar cell field over the past several years, after Professor Henry Snaith’s group at Oxford University found them to be remarkably efficient at converting light to electricity. In just two short years, perovskite-based solar cells have reached efficiencies of nearly 20%, a level which took conventional silicon-based 20 years to reach.

ledsmadefrom

Now, researchers from the University of Cambridge, University of Oxford and the Ludwig-Maximilians-Universität in Munich have demonstrated a new application for perovskite , using them to make high-brightness LEDs. The results are published in the journal Nature Nanotechnology.

Perovskite is a general term used to describe a group of materials that have a distinctive crystal structure of cuboid and diamond shapes. They have long been of interest for their superconducting and ferroelectric properties. But in the past several years, their at converting light into electrical energy has opened up a wide range of potential applications.

The perovskites that were used to make the LEDs are known as organometal halide perovskites, and contain a mixture of lead, carbon-based ions and halogen ions known as halides. These materials dissolve well in common solvents, and assemble to form perovskite crystals when dried, making them cheap and simple to make.

“These organometal halide perovskites are remarkable semiconductors,” said Zhi-Kuang Tan, a PhD student at the University of Cambridge’s Cavendish Laboratory and the paper’s lead author. “We have designed the diode structure to confine electrical charges into a very thin layer of the perovskite, which sets up conditions for the electron-hole capture process to produce light emission.”

The perovskite LEDs are made using a simple and scalable process in which a perovskite solution is prepared and spin-coated onto the substrate. This process does not require high temperature heating steps or a high vacuum, and is therefore cheap to manufacture in a large scale. In contrast, conventional methods for manufacturing LEDs make the cost prohibitive for many large-area display applications.

“The big surprise to the semiconductor community is to find that such simple process methods still produce very clean semiconductor properties, without the need for the complex purification procedures required for traditional semiconductors such as silicon,” said Professor Sir Richard Friend of the Cavendish Laboratory, who has led this programme in Cambridge.

“It’s remarkable that this material can be easily tuned to emit light in a variety of colours, which makes it extremely useful for colour displays, lighting and optical communication applications,” said Tan. “This technology could provide a lot of value to the ever growing flat-panel display industry.”

The team is now looking to increase the efficiency of the LEDs and to use them for diode lasers, which are used in a range of scientific, medical and industrial applications, such as materials processing and medical equipment. The first commercially-available LED based on perovskite could be available within five years.

Explore further: Scientists develop pioneering new spray-on solar cells

More information: Nature Nanotechnology, www.nature.com/nnano/journal/v… /nnano.2014.149.html

Read more at: http://phys.org/news/2014-08-material-perovskite.html#jCp

Supercomputer Speed from a Tiny “Chip” that Mimics the Human Brain


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IBM’s new neurosynaptic processor intergrates 1 million neurons and 256 million (414) synapses on a single chip. Credit: IBMResearchers Thursday unveiled a powerful new postage-stamp size chip delivering supercomputer performance using a process that mimics the human brain.

The so-called “neurosynaptic” is a breakthrough that opens a wide new range of computing possibilities from self-driving cars to that can installed on a smartphone, the scientists say.

The researchers from IBM, Cornell Tech and collaborators from around the world said they took an entirely new approach in design compared with previous computer architecture, moving toward a system called “cognitive computing.”

“We have taken inspiration from the cerebral cortex to design this chip,” said IBM chief scientist for brain-inspired computing, Dharmendra Modha, referring to the command center of the brain.

He said existing computers trace their lineage back to machines from the 1940s which are essentially “sequential number-crunching calculators” that perform mathematical or “left brain” tasks but little else.

The new chip dubbed “TrueNorth” works to mimic the “right brain” functions of sensory processing—responding to sights, smells and information from the environment to “learn” to respond in different situations, Modha said.

It accomplishes this task by using a huge network of “neurons” and “synapses,” similar to how the human brain functions by using information gathered from the body’s sensory organs.

The researchers designed TrueNorth with one million programmable neurons and 256 million programmable synapses, on a chip with 4,096 cores and 5.4 billion transistors.

A key to the performance is the extremely low energy use on the new chip, which runs on the equivalent energy of a hearing-aid battery. This can allow a chip installed in a car or smartphone to perform supercomputer calculations in without connecting to the cloud or other network.

Sensor becomes the computer

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Infographic: A brain-inspired chip to transform mobility and Internet of Things through sensory perception. Credit: IBM 

“You could have better sensory processors without the connection to Wi-Fi or the cloud.

This would allow a self-driving vehicle, for example, to detect problems and deal with them even if its data connection is broken.

“It can see an accident about to happen,” Modha said.

Similarly, a mobile phone can take smells or visual information and interpret them in real time, without the need for a network connection.

“After years of collaboration with IBM, we are now a step closer to building a computer similar to our brain,” said Rajit Manohar, a researcher at Cornell Tech, a graduate school of Cornell University.

The project funded by the US Defense Advanced Research Projects Agency (DARPA) published its research in a cover article on the August 8 edition of the journal Science.

The researchers say TrueNorth in some ways outperforms today’s supercomputers although a direct comparison is not possible because they operate differently.

But they wrote that TrueNorth can deliver from 46 billion to 400 billion “synaptic” calculations per second per watt of energy. That compares with the most energy-efficient supercomputer which delivers 4.5 billion “floating point” calculations per second and per watt.

The chip was fabricated using Samsung’s 28-nanometer process technology.

“It is an astonishing achievement to leverage a process traditionally used for commercially available, low-power mobile devices to deliver a chip that emulates the by processing extreme amounts of sensory information with very little power,” said Shawn Han of Samsung Electronics, in a statement.

“This is a huge architectural breakthrough that is essential as the industry moves toward the next-generation cloud and big-data processing.”

Modha said the researchers have produced only the chip and that it could be years before commercial applications become available.

But he said it “has the potential to transform society” with a new generation of computing technology. And he noted that hybrid computers may be able to one day combine the “left brain” machines with the new “right brain” devices for even better performance.

Explore further: IBM to spend $3 bn aiming for computer chip breakthrough

More information: “A million spiking-neuron integrated circuit with a scalable communication network and interface,” by P.A. Merolla et al. Science, 2014. www.sciencemag.org/lookup/doi/… 1126/science.1254642

Efficient Triple-Junction Polymer Solar Cell Design Sets New Record


Triple Junc SC id36745_1. Copyright © Nanowerk

Organic solar cells are conventionally made from two materials: a donor and an acceptor, which facilitates an efficient charge separation. For the acceptor, the most commonly used molecule is one of the blue absorbing fullerenes. This leaves the absorption spectrum of the donor material responsible to cover as much as possible of the solar spectrum. But most organic semiconductors only have a small optical bandwidth.

Consequently, solar cells based on such materials only catch a small part of the solar spectrum. This problem can be overcome with a properly designed stacked or tandem configuration, in which several organic materials are tuned so that each absorbs a separate part of the spectrum, thereby increasing the efficiency of the overall device. High bandgap semiconductor materials are used to absorb the short wavelength radiation, with longer wavelength parts transmitted to subsequent semiconductors.

In this context, researchers have set great hopes in the development of multi-junction solar cells, hoping to substantially exceed the performance of single-junction organic photovoltaics. In theory, a solar cell with an infinite number of junctions could obtain a maximum power conversion efficiency (PCE) of nearly 87% under highly concentrated sun light.

The challenge is to develop a semiconductor material system that can attain a wide range of bandgaps and be grown with high crystalline quality. New research coming out of the Yang Yang lab at the University of California, Los Angeles (UCLA), one of the leading labs for organic tandem solar cell research, presents an efficient design for a triple-junction organic tandem solar cell featuring a configuration of bandgap energies designed to maximize the tandem photocurrent output.

The key innovation in this study, reported in the July 14, 2014 online edition of Advanced Materials (“An Efficient Triple-Junction Polymer Solar Cell Having a Power Conversion Efficiency Exceeding 11%”), is the demonstration of organic materials being able to mimic the record-setting efficiency of triple-junction structures in III-V solar cells. III-V based solar cells constructed with the industry-standard GaInP/GaInAs/Ge technology have achieved the highest energy conversion efficiencies of all solar cells, with the current record exceeding 40%.

“In III–V multijunction solar cells, the optimal arrangement for a high-current-output triple-junction tandem cell features one wide-bandgap absorber (2.0–1.85 eV), one medium-bandgap absorber (1.4–1.2 eV), and one low-bandgap absorber (1.0–0.7 eV)”, Chun-Chao Chen, a graduate student in Yang’s lab and first author of the paper, explains to Nanowerk. “This optimal design rule cannot be applied directly to organic solar cells, however, because of the lack of efficient donor materials having bandgaps as low as 1 eV. Therefore, we set out to determine a practical combination of bandgap energies for triple junctions to develop an efficient organic tandem solar cell structure.”

 

 

Layer stacks of a triple-junction tandem solar cell

Schematic representation of the complete device structure: Layer stacks of the triple-junction tandem solar cell in the inverted architecture. (Reprinted with permission by Wiley-VCH Verlag)

For their design, the team used three materials with different energy bandgaps (1.9, 1.58, and 1.4 eV) as electron donors, blended with fullerene derivatives. With this arrangement of bandgap energies, they fabricated a highly efficient triple-junction tandem solar cell having a PCE of 11% – exceeding the record efficiency of a double-junction tandem solar cell, previously demonstrated by Yang’s group as well.

Energy levels of various materials for solar cells

 

Energy levels of the materials investigated in this study. Values for ITO, ZnO, and WO3 were measured using ultraviolet photoelectron spectroscopy (UPS); other values were taken from the literature. (Reprinted with permission by Wiley-VCH Verlag)

 

The specific problem in triple-junction solar cells is the complicated optical interference effect between each subcell included in the tandem. “When there are two junctions in tandem, the optical effect is easy to resolve,” say the UCLA researchers. “However, when it comes to triple junctions, you can not use trial and error to find out the optimal layer thickness for absorption for each subcell.”

To solve this issue, and in order to understand how each subcell works and how much current it can deliver, the team carried out in-depth and detailed optical simulations for each subcell. Benefiting from this tool, they came up with a simple and effective structure for connecting the subcells in tandem solar cells. This interconnecting structure, made of WO3/PEDOT:PSS/ZnO, is completely solution processed, thus keeping the orthogonal processing advantage of organic solar cells unchanged – regardless of how many junctions are added.

According to the UCLA team, “this design significantly strengthens our faith in tandem structure for organic solar cell.” They also points out that one of the outcomes of this study is the message that innovations in device architecture can potentially push the efficiencies of organic solar cell technology into the realm of inorganic photovoltaics.

The team is confident that their experience and knowledge gained from designing tandem solar cells can be transferred to other photovoltaic technologies – e.g. hybrid solar cells; perovskite solar cell; CIGS solar cells. Last year, for instance, they have shown that tandem structures can be combined with existing semitransparent solar cell design can result in a doubling of efficiency (read more: “Transparent film could coat windows, smartphone screens with energy-harvesting material“).

Read more: Efficient triple-junction polymer solar cell design sets new record http://www.nanowerk.com/spotlight/spotid=36745.php#ixzz39Ya0Onsn

Translating Science into Business: The Business of Organic Semiconductors


 

KAUST karl

“There are many things which can go wrong when starting a company; but the worst thing that can go wrong is to not do it,” said Prof. Karl Leo, Director of KAUST’s Solar & Photovoltaics Engineering Research Center, when speaking at an Entrepreneurship Center speaker series event this past spring. Wearing the dual hats of scientist and entrepreneur, Prof. Leo is the author of 440 publications, holds more than 50 patents, and has co-created 8 companies which have generated over 300 jobs.

A physicist by training, Prof. Leo highlighted the point that he is primarily a scientist who stumbled onto business by chance. “For me it’s always started with and been about the science,” he says. All his spin-off companies came about as a result of basic research he and his group conducted on organic semiconductors. Speaking specifically to the young KAUST researchers hoping to emulate his success as academics and entrepreneurs, Prof. Leo said: “The message I want to pass along is if you really want to do things, just be curious. Don’t say I want to do research to make a company. Do very basic research and the spin-off ideas will come along.”

The Growing Influence of Organic Semiconductors

Prof. Karl Leo started doing research on organic semiconductors about 20 years ago. He has since been passionate about this field’s developments and future potential. Despite his early skepticism resulting from the ephemeral lifetime of organic semiconductors in the ’90s, the performance levels of LED devices for instance have gone from just a few minutes of useful life then to virtually not aging today. “In the long-term, as in 20 to 30 years from now, almost everything will be organics,” he believes. “Silicon has dominated electronics for a long time but organic is something new.” Organic products have evolved into a variety of applications such as: small OLED displays, OLED televisions, OLED lighting, OPV and organic electronics.

Organics, as opposed to traditional silicon-based semiconductors, are by nature essentially lousy semiconductors. Mobility, or the speed at which electrons move on these materials, is a really important property. However, when looking at the electronic properties of semiconductors, carbon offers interesting developments for the performance of organics. For instance, graphene, which is a carbon-based organic material, has even higher mobility than silicon.

Organic Semi untitled

One of the companies Prof. Karl Leo co-founded and began operating out of Dresden, Germany in 2003, Novaled, became a leader in in organic light-emitting diode (OLED) field. OLEDs are made up of multiple thin layers of organic materials, known as OLED stacks. They essentially emit light when electricity is applied to them. Novaled became a pioneer in developing highly efficient and long-lifetime OLED structures; and it currently holds the world record in power efficiency. They key to Novaled’s success, as Prof. Leo explains, is “the simple discovery that you can dope organics.” This was a major breakthrough achieved simply adding a very little amount of another molecule.

This organic conductivity doping technology, used to enhance the performance of OLED devices, was the main factor leading to the company being purchased by Samsung in 2013.

Organic Photovoltaics: Technology of the Future

Following the successful commercial penetration of OLED displays in the consumer electronics market, Prof. Karl Leo has since turned his focus on organic photovoltaics. “I think organic PV is something that can change the world,” said Leo. Among the many advantages of organic photovoltaics are that they are thin organic layers which can be applied on flexible plastic substrates. They consume little energy, can be made transparent, and are compatible with low-cost large-area production technologies. Because they are transparent, they can be made into windows for instance, and also be manufactured in virtually any color. All these characteristics make organic PV ideal for consumer products.

Again based on basic research conducted by his group, Prof. Leo also started a company, Heliatek, which is now a world-leader in the production of organic solar film. Heliatek has developed the current world record in the efficiency of transparent solar cells. The company also holds the record for efficiency of opaque cells at 12 percent. Leo believes that it’s possible to achieve up to 20 percent efficiency in the near future, which will be necessary to compete with silicon and become commercially viable.

Don’t Believe Business Plans

Prof. Leo explained that the experience he and his team gained from launching a successful company like Novaled helped them to both define the objectives and obtain funding from investors for his solar cell company, Heliatek. “Once you create a successful company, things get much easier,” he said. But Leo also cautioned the budding entrepreneurs in the audience to be willing to adapt as they present and implement their ideas.

“If you have a good idea and you are convinced you have a good idea, never give up,” he said. But being able to adapt to market needs is also crucial. For instance, Leo’s original business plan for Novaled focused on manufacturing displays. But the realities of the market, and the prohibitive cost of manufacturing displays, convinced his team that the smarter way to go was to supply materials. At the end of the day, what really succeeded in getting a venture capital firm’s attention, after haven been told no 49 times, was his team’s ability to demonstrate the value of the technology.

“Business plans are useful but they must not be overestimated,” said Prof. Leo. Business plans are a good indicator of how entrepreneurs are able to structure their thoughts, identify markets and create a roadmap, but “nobody is able to predict the future in a business plan; it’s not possible.”

 

Definition of Organic Semi-Conductors: Background

An organic semiconductor is an organic material with semiconductor properties, that is, with an electrical conductivity between that of insulators and that of metals. Single molecules, oligomers, and organic polymers can be semiconductive. Semiconducting small molecules (aromatic hydrocarbons) include the polycyclic aromatic compounds pentacene, anthracene, and rubrene. Polymeric organic semiconductors include poly(3-hexylthiophene), poly(p-phenylene vinylene), as well as polyacetylene and its derivatives.

There are two major overlapping classes of organic semiconductors. These are organic charge-transfer complexes and various linear-backbone conductive polymers derived from polyacetylene. Linear backbone organic semiconductors include polyacetylene itself and its derivatives polypyrrole, and polyaniline.

At least locally, charge-transfer complexes often exhibit similar conduction mechanisms to inorganic semiconductors. Such mechanisms arise from the presence of hole and electron conduction layers separated by a band gap.

Although such classic mechanisms are important locally, as with inorganic amorphous semiconductors, tunnelling, localized states, mobility gaps, and phonon-assisted hopping also significantly contribute to conduction, particularly in polyacetylenes. Like inorganic semiconductors, organic semiconductors can be doped. Organic semiconductors susceptible to doping such as polyaniline (Ormecon) and PEDOT:PSS are also known as organic metals

 

Further Information

Genesis Nanotech Headlines Are Out!


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SUBCOMMITTE EXAMINES BREAKTHROUGH NANOTECHNOLOGY OPPORTUNITIES FOR AMERICA

Chairman Terry: “Nanotech is a true science race between the nations, and we should be encouraging the transition from research breakthroughs to commercial development.”

WASHINGTON, DCThe Subcommittee on Commerce, Manufacturing, and Trade, chaired by Rep. Lee Terry (R-NE), today held a hearing on:

“Nanotechnology: Understanding How Small Solutions Drive Big Innovation.”

 

 

electron-tomography

“Great Things from Small Things!” … We Couldn’t Agree More!

 

Quantum Dots may turn House Windows into Solar Panels


 

New-QD-Solar-Cell-id35756-150x150A house window that doubles as a solar panel could be on the horizon, thanks to recent quantum-dot work by researchers at Los Alamos National Laboratory in the US in collaboration with scientists from University of Milano-Bicocca (UNIMIB) in Italy.

Their work, published earlier this year in Nature Photonics, demonstrates that superior light-emitting properties of quantum dots can be applied in solar energy by helping more efficiently harvest sunlight.

“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 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.

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 toward the slab edge equipped with a solar cell.

Quantum dots are embedded in the plastic matrix and capture sunlight to improve solar-panel efficiency.
Courtesy Los Alamos Lab.
 
LUMINESCENT SOLAR CONCENTRATOR AS LIGHT HARVESTER

Sergio Brovelli, a faculty member at UNIMIB and a co-author of the paper, 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.”

Because of highly efficient, color-tunable emission and solution processability, quantum dots are attractive materials for use in inexpensive, large-area LSCs. To overcome a nagging problem of light reabsorption, the Los Alamos and UNIMIB researchers developed LSCs based on quantum dots with artificially induced large separation between emission and absorption bands, known as 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.

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 across) of polymethylmethacrylate. While being large by quantum dot standards, the active particles are still tiny, only about hundred angstroms across.

QUANTUM DOTS USED FOR NEW DISPLAYS

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%.3D Printing dots-2

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.

In a new SPIE.TV video, Lawrence Berkeley National Lab director Paul Alivisatos demonstrates the Kindle Fire quantum-dot display.

 

DOI: 10.1117/2.4201407.10

Subcommittee Examines Breakthrough Nanotechnology Opportunities for America


Applications-of-Nanomaterials-Chart-Picture1SUBCOMMITTE EXAMINES BREAKTHROUGH NANOTECHNOLOGY OPPORTUNITIES FOR AMERICA
July 29, 2014

WASHINGTON, DCThe Subcommittee on Commerce, Manufacturing, and Trade, chaired by Rep. Lee Terry (R-NE), today held a hearing on “Nanotechnology: Understanding How Small Solutions Drive Big Innovation.” Nanotechnology is science, engineering, and technology conducted at the nanoscale, which is approximately 1 to 100 nanometers (one nanometer is a billionth of a meter). This technology brings great opportunities to advance a broad range of industries, bolster our U.S. economy, and create new manufacturing jobs. Members heard from several nanotech industry leaders about the current state of nanotechnology and the direction that it is headed.UNIVERSITY OF WATERLOO - New $5 million lab

“Just as electricity, telecommunications, and the combustion engine fundamentally altered American economics in the ‘second industrial revolution,’ nanotechnology is poised to drive the next surge of economic growth across all sectors,” said Chairman Terry.

 

 

Applications of Nanomaterials Chart Picture1

Dr. Christian Binek, Associate Professor at the University of Nebraska-Lincoln, explained the potential of nanotechnology to transform a range of industries, stating, “Virtually all of the national and global challenges can at least in part be addressed by advances in nanotechnology. Although the boundary between science and fiction is blurry, it appears reasonable to predict that the transformative power of nanotechnology can rival the industrial revolution. Nanotechnology is expected to make major contributions in fields such as; information technology, medical applications, energy, water supply with strong correlation to the energy problem, smart materials, and manufacturing. It is perhaps one of the major transformative powers of nanotechnology that many of these traditionally separated fields will merge.”

Dr. James M. Tour at the Smalley Institute for Nanoscale Science and Technology at Rice University encouraged steps to help the U.S better compete with markets abroad. “The situation has become untenable. Not only are our best and brightest international students returning to their home countries upon graduation, taking our advanced technology expertise with them, but our top professors also are moving abroad in order to keep their programs funded,” said Tour. “This is an issue for Congress to explore further, working with industry, tax experts, and universities to design an effective incentive structure that will increase industry support for research and development – especially as it relates to nanotechnology. This is a win-win for all parties.”

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Professor Milan Mrksich of Northwestern University discussed the economic opportunities of nanotechnology, and obstacles to realizing these benefits. He explained, “Nanotechnology is a broad-based field that, unlike traditional disciplines, engages the entire scientific and engineering enterprise and that promises new technologies across these fields. … Current challenges to realizing the broader economic promise of the nanotechnology industry include the development of strategies to ensure the continued investment in fundamental research, to increase the fraction of these discoveries that are translated to technology companies, to have effective regulations on nanomaterials, to efficiently process and protect intellectual property to ensure that within the global landscape, the United States remains the leader in realizing the economic benefits of the nanotechnology industry.”

James Phillips, Chairman & CEO at NanoMech, Inc., added, “It’s time for America to lead. … We must capitalize immediately on our great University system, our National Labs, and tremendous agencies like the National Science Foundation, to be sure this unique and best in class innovation ecosystem, is organized in a way that promotes nanotechnology, tech transfer and commercialization in dramatic and laser focused ways so that we capture the best ideas into patents quickly, that are easily transferred into our capitalistic economy so that our nation’s best ideas and inventions are never left stranded, but instead accelerated to market at the speed of innovation so that we build good jobs and improve the quality of life and security for our citizens faster and better than any other country on our planet.”

Chairman Terry concluded, “Nanotech is a true science race between the nations, and we should be encouraging the transition from research breakthroughs to commercial development. I believe the U.S. should excel in this area.”

– See more at: http://energycommerce.house.gov/press-release/subcommittee-examines-breakthrough-nanotechnology-opportunities-america#sthash.YnSzFU10.dpuf

Low Cost Laser Technique Improves Electrical & Photo Conductivity in Nanomaterials


NUS Laser 49845NUS scientists use low cost technique to improve properties and functions of nanomaterials: By ‘drawing’ micropatterns on nanomaterials using a focused laser beam, scientists could modify properties of nanomaterials for effective applications in photonic and optoelectric applications

Singapore | Posted on July 22nd, 2014

Through the use of a simple, efficient and low cost technique involving a focused laser beam, two NUS research teams, led by Professor Sow Chorng Haur from the Department of Physics at the NUS Faculty of Science, demonstrated that the properties of two different types of materials can be controlled and modified, and consequently, their functionalities can be enhanced.

Said Prof Sow, “In our childhood, most of us are likely to have the experience of bringing a magnifying glass outdoors on a sunny day and tried to focus sunlight onto a piece of paper to burn the paper. Such a simple approach turns out to be a very versatile tool in research. Instead of focusing sunlight, we can focus laser beam onto a wide variety of nanomaterials and study effects of the focused laser beam has on these materials.”

NUS Laser 49845

Mesoporous silicon nanowires were scanned by a focused laser beam in two different patterns, imaged by bright-field optical microscope, as depicted by (a) and (c), as well as fluorescence microscopy, as depicted by (b) and (d). Evidently, the images hidden in boxes shown in (a) and (c) are clearly revealed under fluorescence microscopy.

Micropatterns ‘drawn’ on MoS2 films could enhance electrical conductivity and photo conductivity

Molybdenum disulfide (MoS2), a class of transition metal dichalcogenide compound, has attracted great attention as an emerging two-dimensional (2D) material due to wide recognition of its potential in and optoelectronics. One of the many fascinating properties of 2D MoS2 film is that its properties depend on the thickness of the film. In addition, its properties can be modified once the film is modified chemically. Hence one of the challenges in this field is the ability to create microdevices out of the MoS2 film comprising components with different thickness or chemical nature.

To address this technological challenge, Prof Sow, Dr Lu Junpeng, a postdoctoral candidate from the Department of Physics at the NUS Faculty of Science, as well as their team members, utilised an optical microscope-focused laser beam setup to ‘draw’ micropatterns directly onto large area MoS2 films as well as to thin the films.

With this simple and low cost approach, the scientists were able to use the focused laser beam to selectively ‘draw’ patterns onto any region of the film to modify properties of the desired area, unlike other current methods where the entire film is modified.

Interestingly, they also found that the electrical conductivity and photoconductivity of the modified material had increased by more than 10 times and about five times respectively. The research team fabricated a photodetector using laser modified MoS2 film and demonstrated the superior performance of MoS2 for such application.

This innovation was first published online in the journal ACS Nano on 24 May 2014.

Hidden images ‘drawn’ by focused laser beam on silicon nanowires could improve optical functionalities

In a related study published in the journal Scientific Reports on 13 May 2014, Prof Sow led another team of researchers from the NUS Faculty of Science, in collaboration with scientists from Hong Kong Baptist University, to investigate how ‘drawing’ micropatterns on mesoporous silicon nanowires could change the properties of nanowires and advance their applications.

The team scanned a focused laser beam rapidly onto an array of mesoporous silicon nanowires, which are closely packed like the tightly woven threads of a carpet. They found that the focused laser beam could modify the optical properties of the nanowires, causing them to emit greenish-blue fluorescence light. This is the first observation of such a laser-modified behaviour from the mesoporous silicon nanowires to be reported.

The researchers systematically studied the laser-induced modification to gain insights into establishing control over the optical properties of the mesoporous silicon nanowires. Their understanding enabled them to ‘draw’ a wide variety of micropatterns with different optical functionalities using the focused laser beam.

To put their findings to the test, the researchers engineered the functional components of the nanowires with interesting applications. The research team demonstrated that the micropatterns created at a low laser power are invisible under bright-field optical microscope, but become apparent under fluorescence microscope, indicating the feasibility of hidden images.

Further research

The fast growing field of electronics and optoelectronics demands precise material deposition with application-specific optical, electrical, chemical, and mechanical properties.

To develop materials with properties that can cater to the industry’s demands, Prof Sow, together with his team of researchers, will extend the versatile focused laser beam technique to more nanomaterials. In addition, they will look into further improving the properties of MoS2 and mesoporous silicon with different techniques.

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