Nanotechnology Makes LED Displays Brighter, Clearer & Cheaper to Make


1-LED's shutterstock_146111753Nanotechnology attempts to control atoms and molecules on the scale of less than 100 nanometers. A nanometer is one-billionth of a meter. So, imagine trying to build a computer chip or microscopic device in this small space!

Stephen Chou has dominated the field of nanotechnology in recent years. He is a Packard Fellow, an inductee of the New Jersey Technology Hall of Fame and has published almost 300 scientific papers. He currently holds 15 patents and has applied for over 40 more. Furthermore, Chou is the founder of Nanonex Corporation and NanoOpto Corporation.

1-LED's shutterstock_146111753

In 2012, Stephen Chou used nanotechnology to show researchers and manufacturers how to almost double the efficiency of solar cells. Now, he has turned his attention to the construction of LEDs (light-emitting diodes). Consequently, consumer products may soon boast that their LED displays are 57 percent more energy efficient, 57 percent brighter and deliver 400 percent more clarity. This technology will be especially important for future smartphones. And while Apple fans are (rightfully so) raving over the new iPhone 6, Chou says the new technology will produce screens that are easier to see, much more defined and will last up to 10 times longer.

Nanotechnology for LEDs

Current nanotechnology allows for working at the level of about 90 nanometers; however, Chou’s technique will reduce that playing field down to 10 nanometers. Chou’s team can actually bend light at a sub-wavelength dimension, which enables them to ensure that more of the light emitted reaches the surface.

The physical structure incorporated is known as PlaCSH (plasmonic cavity with subwavelength hole array). With PlaCSH, Chou’s team achieved a light extraction level of 60 percent, reports ScienceDaily, which is an incredible leap for the 3 percent that we see in cell phones currently. Chou states, “New nanotechnology can change the rules of the ways we manipulate light. We can use this to make devices with unprecedented performance.” That means you will see more clearly, not just on your smartphone screen, but with any device—whether automotive, instrument-fixed or appliance-based that incorporates LED lighting.

Other Uses of Nanotechnology

Chou’s work also has been applied to the world of medicine. One of the areas where nanotechnology may apply is immunoassay, which is a standard test used in the early detection of medical conditions like Alzheimer’s disease and cancer. Thanks to nanotechnology, immunoassay could become 3 million times more sensitive.

Immunoassay uses biomarkers, or the chemicals linked with diseases, and when those markers are present, then the test produces a fluorescent glow, explains Princeton’s School of Engineering and Applied Science. The brighter the light, the more biomarkers that are present. Nanotechnology will help make this process even more sensitive because it can detect fainter traces of light. Chou and other researchers at Princeton created gold and glass structures that were small enough to be seen with an electron microscope and increased the flueorescence signal of the immunoassays. Overall, this means your chances of early detection of a serious disease would increase exponentially.

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Engineers efficiently ‘mix’ light at the nanoscale


1A-engineerseffThe race to make computer components smaller and faster and use less power is pushing the limits of the properties of electrons in a material. Photonic systems could eventually replace electronic ones, but the fundamentals of computation, mixing two inputs into a single output, currently require too much space and power when done with light.

Researchers at the University of Pennsylvania have engineered a nanowire system that could pave the way for this ability, combining two waves to produce a third with a different frequency and using an to amplify the intensity of the output to a usable level.

The study was led by Ritesh Agarwal, professor of materials science and engineering in Penn’s School of Engineering and Applied Science, and Ming-Liang Ren, a post-doctoral researcher in his lab. Other members of the Agarwal lab, Wenjing Liu, Carlos O. Aspetti and Liaoxin Sun, contributed to the study.

1A-engineerseff

It was published in Nature Communications.

Current computer systems represent bits of information—the 1’s and 0’s of binary code—with electricity. Circuit elements, such as transistors, operate on these , producing outputs that are dependent on their inputs.

“Mixing two input signals to get a new output is the basis of computation,” Agarwal said. “It’s easy to do with electric signals, but it’s not easy to do with light, as light waves don’t normally interact with one another.”

Engineers efficiently ‘mix’ light at the nanoscale
                                                        A schematic of the optical cavity.

The difficulty inherent in “mixing” light may seem counterintuitive, given the gamut of colors on TV or computer screen that are produced solely by combinations of red, green and blue pixels. The yellows, oranges and purples those displays make, however, are a trick of perception, not of physics. Red and blue light are simply experienced simultaneously, rather than combined into a single purple wavelength.

So-called “nonlinear” materials are capable of this kind of mixing, but even the best candidates in this category are not yet viable for computational applications due to high power and large volume constraints.

“A nonlinear material, such a , can change the frequency, and thus the color, of light that passes through it,” Ren said, “but you need a powerful laser, and, even so, the material needs to be a many micrometers and even up to millimeters thick. That doesn’t work for a computer chip.”

To reduce the volume of the material and the power of the light needed to do useful signal mixing, the researchers needed a way to amplify the intensity of a light wave as it passed through a cadmium sulfide nanowire.

The researchers achieved this through a clever bit of optical engineering: partially wrapping the nanowire in a silver shell that acts like an echo chamber. Agarwal’s group had employed a similar design before in an effort to create photonic devices that could switch on and off very rapidly. This quality relied on a phenomenon known as , but, by changing the polarization of the light as it entered the nanowire, the researchers were able to better confine it to the frequency-altering, nonlinear part of the device: the nanowire core.

“By engineering the structure so that light is mostly contained within the cadmium sulfide rather than at the interface between it and the silver shell, we can maximize the intensity while generating the second harmonic,” Ren said.

Like a second harmonic played on a guitar string, this meant doubling the frequency of the . Information in a photonic computer system could be encoded in a wave’s frequency, or the number of oscillations it makes in a second. Being able to manipulate that quality in one wave with another allows for the fundamentals of computer logic.

“We want to show we can sum two frequencies of light,”Agarwal said, “so we simplified the experiment. By taking one frequency and adding it to itself, you get double the frequency in the end. Ultimately, we want to be able to tune the light to whatever frequency is needed, which can be done by altering the size of the nanowire and the shell.”

Most important, however, was that this frequency mixing was possible on the nanoscale with very high efficiency. The researchers’ optical cavity was able to increase the output wave’s intensity by more than a thousand times.

“The -changing efficiency of cadmium sulfide is intrinsic to the material, but it depends on the volume of the material the wave passes through,” Agarwal said. “By adding the silver shell, we can significantly decrease the volume needed to get a usable signal and push the device size into the nanoscale.”

Explore further: Researchers invent ‘meta mirror’ to help advance nonlinear optical systems

Quantum Materials Corp to Quadruple Lab Space and Add Scientists


1-QMC Star Park 156698SAN MARCOS, Texas, Nov. 5, 2014 /PRNewswire/ — Quantum Materials Corp (OTCQB:QTMM) today announced it has signed an agreement with STAR Park that will quadruple the Company’s Quantum Dot production space when the new state-of-the-art lab and offices are completed on or before June 2015. The Company is also recruiting to double its scientific staff effective January 2015.

“It is extremely gratifying that our work is meeting with industry acceptance from some of the most technologically advanced companies in the world,” said Quantum Materials Founder and CEO Stephen Squires. “Our expansion demonstrates our commitment to meet the demands of next-generation television and display, solid-state lighting and solar energy manufacturers. We will be bringing to San Marcos top scientists and chemists to develop non-heavy metal tetrapod quantum dots and thick-shell technology to optimize them for each client’s purpose and to their true commercial potential.”

In a recent Reuters News article Samsung and LG Display discussed the use of quantum dots to create the next-generation Ultra High Definition televisions rather than Organic Light Emitting Diodes (OLED). In the article an industry analyst estimates that a 55-inch quantum dot TV would only cost consumers about 35 percent more than a current LCD TV, while an OLED TV could be 5 times more expensive. Quantum Materials’ patented and automated process for quantum dot manufacture can further reduce manufacturer’s costs through economies of scale.

At this time, there are a few heavy metal (Cadmium-based) quantum dot televisions on the market. Quantum Materials is aware of ecological concerns about Cadmium and is currently developing non-heavy metal (NHM) quantum dots under Company-owned patents for the Ultra High Definition display market. Industry research has shown NHM quantum dots to be environmentally friendly but have yet to demonstrate NHM quantum dots of a quality, quantity, reliability and price necessary to justify industrial production. The company believes these problems will be overcome with our current intellectual property, automated processes and top scientific personnel.

About Quantum Materials Corp

Quantum Materials Corp develops and manufactures Tetrapod Quantum Dots for use in medical, display, solar energy and lighting applications through its patent-pending volume production process. QMC’s volume manufacturing methods enable consistent quality and scalable cost reductions to drive innovative discovery to commercial success. (www.qmcdots.com) Wholly-owned subsidiary Solterra Renewable Technologies develops sustainable solar technology by replacing silicon wafer-based solar cells with high-production, low-cost, efficient and flexible thin-film quantum dot solar cells. (www.solterrarenewable.com)

Safe Harbor statement under the Private Securities Litigation Reform Act of 1995

This press release contains forward-looking statements that involve risks and uncertainties concerning business, products, and financial results. Actual results may differ materially from the results predicted. More information about potential risk factors that could affect our business, products, and financial results are included in our annual report and in reports subsequently filed with the Securities and Exchange Commission (“SEC”). All documents are available through the SEC’s EDGAR System at http://www.sec.gov/ orwww.QMCdots.com. We hereby disclaim any obligation to publicly update the information provided above, including forward-looking statements, to reflect subsequent events or circumstances.

A brighter design emerges for low-cost, “greener” LED light bulbs


GreenerLEDThe phase-out of traditional incandescent bulbs in the U.S. and elsewhere, as well as a growing interest in energy efficiency, has given LED lighting a sales boost. However, that trend could be short-lived as key materials known as rare earth elements become more expensive. Scientists have now designed new materials for making household LED bulbs without using these ingredients. They report their development in ACS’ Journal of the American Chemical Society.

LED lighting, which can last years longer than conventional bulbs, is an energy-efficient alternative. Switching lighting to LEDs over the next two decades, reports the U.S. Department of Energy, “could save the country $250 billion in energy costs over that period, reduce the electricity consumption for lighting by nearly one half, and avoid 1,800 million metric tons of carbon emission.” White LED bulbs are already on store shelves, but the light is generally “colder” than the warm glow of traditional bulbs. Plus, most of these lights are made with rare earth elements that are increasingly in-demand for use in almost all other high-tech devices, thus adding to the cost of the technology. Jing Li’s research team set out to solve the issues of material sources and pricing.

GreenerLED

A new way to make white and colorful LEDs is more Earth-friendly than existing methods. Image: American Chemical Society

The researchers designed a family of materials that don’t include rare earths but instead are made out of copper iodide, which is an abundant compound. They tuned them to glow a warm white shade or various other colors using a low-cost solution process. “Combining these features, this material class shows significant promise for use in general lighting applications,” the scientists conclude.

The authors acknowledge funding from the National Science Foundation.

Systematic Approach in Designing Rare-Earth-Free Hybrid Semiconductor Phosphors for General Lighting Applications

Source: American Chemical Society

‘Nano-pixels’ promise thin, flexible, high resolution displays


A new discovery will make it possible to create pixels just a few hundred nanometres across that could pave the way for extremely high-resolution and low-energy thin, flexible displays for applications such as ‘smart’ glasses, synthetic retinas, and foldable screens.

Nano Pixels 140709140115-largeA team led by Oxford University scientists explored the link between the electrical and optical properties of phase change materials (materials that can change from an amorphous to a crystalline state). They found that by sandwiching a seven nanometre thick layer of a phase change material (GST) between two layers of a transparent electrode they could use a tiny current to ‘draw’ images within the sandwich ‘stack’.

Initially still images were created using an atomic force microscope but the team went on to demonstrate that such tiny ‘stacks’ can be turned into prototype pixel-like devices. These ‘nano-pixels’ — just 300 by 300 nanometres in size — can be electrically switched ‘on and off’ at will, creating the coloured dots that would form the building blocks of an extremely high-resolution display technology.

A report of the research is published in this week’s Nature.

‘We didn’t set out to invent a new kind of display,’ said Professor Harish Bhaskaran of Oxford University’s Department of Materials, who led the research. ‘We were exploring the relationship between the electrical and optical properties of phase change materials and then had the idea of creating this GST ‘sandwich’ made up of layers just a few nanometres thick. We found that not only were we able to create images in the stack but, to our surprise, thinner layers of GST actually gave us better contrast. We also discovered that altering the size of the bottom electrode layer enabled us to change the colour of the image.’

Nano Pixels 140709140115-large
Oxford University technology can draw images 70 micrometers across, each image is smaller than the width of a human hair. The researchers have shown that using this technology they can create ‘nano-pixels’ just 100 nanometers in size that could pave the way for extremely high-resolution and low-energy thin, flexible displays for applications such as ‘smart’ glasses, synthetic retinas, and foldable screens.
 

Whilst the work is still in its early stages, realising its potential, the Oxford team has filed a patent on the discovery with the help of Isis Innovation, Oxford University’s technology commercialisation company. Isis is now discussing the displays with companies who are interested in assessing the technology, and with investors.

The layers of the GST sandwich are created using a sputtering technique where a target is bombarded with high energy particles so that atoms from the target are deposited onto another material as a thin film.

‘Because the layers that make up our devices can be deposited as thin films they can be incorporated into very thin flexible materials — we have already demonstrated that the technique works on flexible Mylar sheets around 200 nanometres thick,’ said Professor Bhaskaran. ‘This makes them potentially useful for ‘smart’ glasses, foldable screens, windshield displays, and even synthetic retinas that mimic the abilities of photoreceptor cells in the human eye.’

Peiman Hosseini of Oxford University’s Department of Materials, first author of the paper, said: ‘Our models are so good at predicting the experiment that we can tune our prototype ‘pixels’ to create any colour we want — including the primary colours needed for a display. One of the advantages of our design is that, unlike most conventional LCD screens, there would be no need to constantly refresh all pixels, you would only have to refresh those pixels that actually change (static pixels remain as they were). This means that any display based on this technology would have extremely low energy consumption.’

The research suggests that flexible paper-thin displays based on the technology could have the capacity to switch between a power-saving ‘colour e-reader mode’, and a backlit display capable of showing video. Such displays could be created using cheap materials and, because they would be solid-state, promise to be reliable and easy to manufacture. The tiny ‘nano-pixels’ make it ideal for applications, such as smart glasses, where an image would be projected at a larger size as, even enlarged, they would offer very high-resolution.

Professor David Wright of the Department of Engineering at the University of Exeter, co-author of the paper, said: ‘Along with many other researchers around the world we have been looking into the use of these GST materials for memory applications for many years, but no one before thought of combining their electrical and optical functionality to provide entirely new kinds of non-volatile, high-resolution, electronic colour displays — so our work is a real breakthrough.’

The phase change material used was the alloy Ge2Sb2Te5 (Germanium-Antimony-Tellurium or GST) sandwiched between electrode layers made of indium tin oxide (ITO).

Researchers Create Quantum Dots with Single-Atom Precision: Naval Research Center


 

Washington, DC | Posted on June 30th, 2014

single QD Naval R 49744Quantum dots are often regarded as artificial atoms because, like real atoms, they confine their electrons to quantized states with discrete energies. But the analogy breaks down quickly, because while real atoms are identical, quantum dots usually comprise hundreds or thousands of atoms – with unavoidable variations in their size and shape and, consequently, in their properties and behavior. External electrostatic gates can be used to reduce these variations. But the more ambitious goal of creating quantum dots with intrinsically perfect fidelity by completely eliminating statistical variations in their size, shape, and arrangement has long remained elusive.

Creating atomically precise quantum dots requires every atom to be placed in a precisely specified location without error. The team assembled the dots atom-by-atom, using a scanning tunneling microscope (STM), and relied on an atomically precise surface template to define a lattice of allowed atom positions. The template was the surface of an InAs crystal, which has a regular pattern of indium vacancies and a low concentration of native indium adatoms adsorbed above the vacancy sites. The adatoms are ionized +1 donors and can be moved with the STM tip by vertical atom manipulation. The team assembled quantum dots consisting of linear chains of N = 6 to 25 indium atoms; the example shown here is a chain of 22 atoms.

single QD Naval R 49744
This image shows quantized electron states, for quantum numbers n = 1 to 6, of a linear quantum dot consisting of 22 indium atoms positioned on the surface of an InAs crystal.
Image: Stefan Fölsch/PDI

Stefan Fölsch, a physicist at the PDI who led the team, explained that “the ionized indium adatoms form a quantum dot by creating an electrostatic well that confines electrons normally associated with a surface state of the InAs crystal. The quantized states can then be probed and mapped by scanning tunneling spectroscopy measurements of the differential conductance.” These spectra show a series of resonances labeled by the principal quantum number n. Spatial maps reveal the wave functions of these quantized states, which have n lobes and n – 1 nodes along the chain, exactly as expected for a quantum-mechanical electron in a box. For the 22-atom chain example, the states up to n = 6 are shown.

Because the indium atoms are strictly confined to the regular lattice of vacancy sites, every quantum dot with N atoms is essentially identical, with no intrinsic variation in size, shape, or position. This means that quantum dot “molecules” consisting of several coupled chains will reflect the same invariance. Steve Erwin, a physicist at NRL and the team’s theorist, pointed out that “this greatly simplifies the task of creating, protecting, and controlling degenerate states in quantum dot molecules, which is an important prerequisite for many technologies.” In quantum computing, for example, qubits with doubly degenerate ground states offer protection against environmental decoherence.

By combining the invariance of quantum dot molecules with the intrinsic symmetry of the InAs vacancy lattice, the team created degenerate states that are surprisingly resistant to environmental perturbations by defects. In the example shown here, a molecule with perfect three-fold rotational symmetry was first created and its two-fold degenerate state demonstrated experimentally. By intentionally breaking the symmetry, the team found that the degeneracy was progressively removed, completing the demonstration.

The reproducibility and high fidelity offered by these quantum dots makes them excellent candidates for studying fundamental physics that is typically obscured by stochastic variations in size, shape, or position of the chains. Looking forward, the team also anticipates that the elimination of uncontrolled variations in quantum dot architectures will offer many benefits to a broad range of future quantum dot technologies in which fidelity is important.

####

About Naval Research Laboratory

The U.S. Naval Research Laboratory is the Navy’s full-spectrum corporate laboratory, conducting a broadly based multidisciplinary program of scientific research and advanced technological development. The Laboratory, with a total complement of nearly 2,800 personnel, is located in southwest Washington, D.C., with other major sites at the Stennis Space Center, Miss., and Monterey, Calif. NRL has served the Navy and the nation for over 90 years and continues to meet the complex technological challenges of today’s world. For more information, visit the NRL homepage or join the conversation on Twitter, Facebook, and YouTube.

For more information, please click here

Contacts:
Donna McKinney
donna.mckinney@nrl.navy.mil
202-404-3322

Copyright © Naval Research Laboratory

Quantum Dot Manufacturing Company Secures Technology to 3D Print Quantum Dots for Anti-Counterfeiting


3D Printing dots-2(Re-Posted Article: by · June 30, 2014: Original Post in Va. Tech NT News) Quantum mechanics, it’s certainly an intriguing and almost spooky field, but over the next decade or two we will see a major shift in the understanding and utilization of the various applications of quantum physics. One company based in San Marcos, Texas is already working on 3D printing technologies which are within the quantum realm.

Quantum Materials Corporation has been researching and producing quantum dots for several years now. Quantum dots are the tiny little nanocrystals which are produced from semiconductor materials. They are so tiny, that they take on quantum mechanical properties. Today the company announced that they have secured a specific type of quantum dot technology which has been developed by the Institute for Critical Technology and Applied Science and the Design, Research, and Education for Additive Manufacturing Systems (DREAMS) Laboratory at Virginia Tech.

 

Quantum Dots

The technology is based around a patented process which embeds tiny quantum dots into products during a 3D printing process, so that their manufacturers can detect counterfeits. The quantum dots are embedded in such a way that they create an unclonable signature of sorts. Only the manufacturers of the products which have these signatures embedded, know what they should be, making it easy for them to detect illegal copies. Such a security feature would work well within a variety of markets.

“The remarkable number of variations of semiconductor nanomaterials properties QMC can manufacture, coupled with Virginia Tech’s anti-counterfeiting process design, combine to offer corporations extreme flexibility in designing physical cryptography systems to thwart counterfeiters, “stated David Doderer, Quantum Materials Corporation VP for Research and Development. “As 3D printing and additive manufacturing technology advances, its ubiquity allows for the easy pirating of protected designs. We are pleased to work with Virginia Tech to develop this technology’s security potential in a way that minimizes threats and maximizes 3D printing’s future impact on product design and delivery by protecting and insuring the integrity of manufactured products.”

Quantum Dots Giving off Different Colored Light

The security that such a technique offers is quite high. Not only can Quantum Materials Corporation print quantum dots into object, and have those dots emit specific colors, but they can print the dots into an object shaped in several different ways. In addition the company has the ability to use dual emission tetrapod quantum dots to give off two different colors at once. Such technology should easily slow down product counterfeiting, by giving each product a nanoscale signature, that only its manufacturers know exists.

As 3D printing technology expands, we will find ourselves in a world rife with intellectual property theft. This new quantum dot technology could give companies the ability to 3D print their own products, while maintaining the ability to make sure others are not doing the same with their proprietary designs.

Quantum Dots (QD) are Set to Explode in the Next 18 Months


atomsinananoQuantum dots (QD) are potentially set to explode in the next 18 months. Companies such as QD Vision and Nanosys have developed scalable solution production processes and are partnering with multi-national OEMs to use quantum dots in displays for consumer products. QDs warm up the colour of the light while increasing its quality (colour rendering index), delivering a superior blend of colour quality, lifetime and efficiency.

QD enhanced applications are currently under development or are in limited production (QD-LED lighting). The end user markets for QDs are potentially very lucrative. Lighting and displays each represent $100 billion plus markets and will continue to grow. QD materials and component therefore are potentially a multi-billion sub-market revenue opportunity just for these sectors. Additional markets in solar, security, thermoelectrics and magnetics could double this potential market.

This 90 page report maps the current and future market for quantum dots and includes:

  • Market revenue estimates for quantum dots to 2024
  • End user markets
  • Company profiles

MAIN MARKETS FOR QUANTUM DOTS

  • Displays – Market drivers, trends, suppliers and products
  • Energy (Photovoltaics and Solid-State Lighting) – Market drivers, trends, suppliers and products
  • Biomedicine – Market drivers, trends, suppliers and products
  • Security – Market drivers, trends, suppliers and products
  • Sensors – Market drivers, trends, suppliers and products

Companies Mentioned

  • American Dye Source
  • American Elements
  • Bayer MaterialScience AG
  • Cyrium Technologies
  • EBioscience
  • Emfutur Technologies
  • Evident Technologies
  • Genefinity S.r.l.
  • Invisage
  • Life Technologies Corporation
  • LG Display Co., Ltd.
  • Nanoco Technologies
  • Nano Axis LLC
  • Nano Optical Materials
  • NanoPhotonica
  • Nanoshel
  • Nanosquare, Inc.
  • Nanosys, Inc.
  • Ocean Nanotech LLC
  • PlasmaChem GmbH
  • QD Laser, Inc.
  • QLight Nanotech
  • QD Solution
  • QD Vision
  • Revolution Lighting Technologies
  • Samsung
  • Sigma-Aldrich
  • Selah Technologies, LLC
  • Solexant Technologies, LLC
  • Voxtel, Inc.

Genesis Nanotechnology Business Summary Chart

GNT Bussiness Summary Chart II

Quantum Materials Ships 20 Grams of Quantum Dots to Major Asia-Based Global Company in First Weeks of Operation of Scaled Production System


atomsinananoSAN MARCOS, Texas, June 19, 2014 Quantum Materials Corporation(OTCQB:QTMM) today announced the shipment of 20 grams of quantum dots to a major Asia-based global company.

 

Quantum Materials accomplished the manufacture in a portion of the first week after installation and commissioning runs of the Company’s new automated production system.  The precision afforded by automating production allows Quantum Materials to produce high performance tetrapod quantum dots and other materials with exacting quality control resulting in uniform structure, and tuned narrow emission FWHM.

Quantum Materials Vice President of Research & Development David Doderer said, “We are confident that our first week’s output paves the way for our successful participation in the quantum dot-enabled market.  While the breadth of possibilities of making different highly functional quantum dots and nanomaterials with specific and custom selectivity of performance characteristics give us much to explore, we have proven the capability of mass production of bespoke products to meet specific consumer product and research market demands.”

This custom delivery is the first of several that Quantum Materials has slated to be produced and shipped to potential partners and clients as requested for varied applications in the optoelectronic, photovoltaic and nanobiology fields.

In optoelectronics, the uniformity of Quantum Materials quantum dots is intended to enhance color gamut and luminescence performance for targeted consumer electronics products. In photovoltaics, longer tetrapod arms exhibit higher conversion of photons for sensors and solar cells, and in nanobio, QMC quantum dots can be used for near-instantaneous, highly accurate results in diagnostic assays, medical imaging and as drug delivery platforms.

New Nanoparticle Production Method at Sandia National Laboratories: Better Lights, Lenses, Solar Cells


 

Sandia Labs id36072Sandia National Laboratories has come up with an inexpensive way to synthesize titanium-dioxide nanoparticles and is seeking partners who can demonstrate the process at industrial scale for everything from solar cells to light-emitting diodes (LEDs).

 
Titanium-dioxide (TiO2) nanoparticles show great promise as fillers to tune the refractive index of anti-reflective coatings on signs and optical encapsulants for LEDs, solar cells and other optical devices. Optical encapsulants are coverings or coatings, usually made of silicone, that protect a device.

 
Industry has largely shunned TiO2 nanoparticles because they’ve been difficult and expensive to make, and current methods produce particles that are too large. Sandia became interested in TiO2 for optical encapsulants because of its work on LED materials for solid-state lighting.

 
Current production methods for TiO2 often require high-temperature processing or costly surfactants — molecules that bind to something to make it soluble in another material, like dish soap does with fat.
Those methods produce less-than-ideal nanoparticles that are very expensive, can vary widely in size and show significant particle clumping, called agglomeration.

 

 
Sandia’s technique, on the other hand, uses readily available, low-cost materials and results in nanoparticles that are small, roughly uniform in size and don’t clump.

 

 
“We wanted something that was low cost and scalable, and that made particles that were very small,” said researcher Todd Monson, who along with principal investigator Dale Huber patented the process in mid-2011 as “High-yield synthesis of brookite TiO2 nanoparticles”.

Sandia Labs id36072 (Low-cost technique produces uniform nanoparticles that don’t clump.)

Their method produces nanoparticles roughly 5 nanometers in diameter, approximately 100 times smaller than the wavelength of visible light, so there’s little light scattering, Monson said. “That’s the advantage of nanoparticles — not just nanoparticles, but small nanoparticles,” he said.

Scattering decreases the amount of light transmission. Less scattering also can help extract more light, in the case of an LED, or capture more light, in the case of a solar cell.

TiO2 can increase the refractive index of materials, such as silicone in lenses or optical encapsulants. Refractive index is the ability of material to bend light. Eyeglass lenses, for example, have a high refractive index.

Practical nanoparticles must be able to handle different surfactants so they’re soluble in a wide range of solvents. Different applications require different solvents for processing.

Technique can be used with different solvents.

“If someone wants to use TiO2 nanoparticles in a range of different polymers and applications, it’s convenient to have your particles be suspension-stable in a wide range of solvents as well,” Monson said. “Some biological applications may require stability in aqueous-based solvents, so it could be very useful to have surfactants available that can make the particles stable in water.”

The researchers came up with their synthesis technique by pooling their backgrounds — Huber’s expertise in nanoparticle synthesis and polymer chemistry and Monson’s knowledge of materials physics. The work was done under a Laboratory Directed Research and Development project Huber began in 2005.

“The original project goals were to investigate the basic science of nanoparticle dispersions, but when this synthesis was developed near the end of the project, the commercial applications were obvious,” Huber said. The researchers subsequently refined the process to make particles easier to manufacture.

Existing synthesis methods for TiO2 particles were too costly and difficult to scale up production. In addition, chemical suppliers ship titanium-dioxide nanoparticles dried and without surfactants, so particles clump together and are impossible to break up. “Then you no longer have the properties you want,” Monson said.

The researchers tried various types of alcohol as an inexpensive solvent to see if they could get a common titanium source, titanium isopropoxide, to react with water and alcohol.

The biggest challenge, Monson said, was figuring out how to control the reaction, since adding water to titanium isopropoxide most often results in a fast reaction that produces large chunks of TiO2, rather than nanoparticles. “So the trick was to control the reaction by controlling the addition of water to that reaction,” he said.

 

 
Textbooks said making nanoparticles couldn’t be done, Sandia persisted
Some textbooks dismissed the titanium isopropoxide-water-alcohol method as a way of making TiO2 nanoparticles. Huber and Monson, however, persisted until they discovered how to add water very slowly by putting it into a dilute solution of alcohol. “As we tweaked the synthesis conditions, we were able to synthesize nanoparticles,” Monson said.

 

 
The next step is to demonstrate synthesis at an industrial scale, which will require a commercial partner. Monson, who presented the work at Sandia’s fall Science and Technology Showcase, said Sandia has received inquiries from companies interested in commercializing the technology.

 

 
“Here at Sandia we’re not set up to produce the particles on a commercial scale,” he said. “We want them to pick it up and run with it and start producing these on a wide enough scale to sell to the end user.”

 

 
Sandia would synthesize a small number of particles, then work with a partner company to form composites and evaluate them to see if they can be used as better encapsulants for LEDs, flexible high-index refraction composites for lenses or solar concentrators. “I think it can meet quite a few needs,” Monson said.

 

 

Source: Sandia National Laboratories