Energy-collecting Windows Dream One-Step Closer


window-solar-id45905

Silicon-based luminescent solar concentrator. While most of the light concentrated to the edge of the silicon-based luminescent solar concentrator is actually invisible, we can better see the concentration effect by the naked eye when the slab is illuminated by a “black light” which is composed of mostly ultraviolet wavelengths. (image: Uwe Kortshagen, University of Minnesota)

February 20, 2017

Researchers at the University of Minnesota and University of Milano-Bicocca are bringing the dream of windows that can efficiently collect solar energy one step closer to reality thanks to high tech silicon nanoparticles.

The researchers developed technology to embed the silicon nanoparticles into what they call efficient luminescent solar concentrators (LSCs). These LSCs are the key element of windows that can efficiently collect solar energy. When light shines through the surface, the useful frequencies of light are trapped inside and concentrated to the edges where small solar cells can be put in place to capture the energy.

The research is published today in Nature Photonics (“Highly efficient luminescent solar concentrators based on Earth-abundant indirect-bandgap silicon quantum dots”).

Windows that can collect solar energy, called photovoltaic windows, are the next frontier in renewable energy technologies, as they have the potential to largely increase the surface of buildings suitable for energy generation without impacting their aesthetics—a crucial aspect, especially in metropolitan areas. LSC-based photovoltaic windows do not require any bulky structure to be applied onto their surface and since the photovoltaic cells are hidden in the window frame, they blend invisibly into the built environment.

The idea of solar concentrators and solar cells integrated into building design has been around for decades, but this study included one key difference—silicon nanoparticles. Until recently, the best results had been achieved using relatively complex nanostructures based either on potentially toxic elements, such as cadmium or lead, or on rare substances like indium, which is already massively utilized for other technologies. Silicon is abundant in the environment and non-toxic. It also works more efficiently by absorbing light at different wavelengths than it emits. However, silicon in its conventional bulk form, does not emit light or luminesce.

“In our lab, we ‘trick’ nature by shrinking the dimension of silicon crystals to a few nanometers, that is about one ten-thousandths of the diameter of human hair,” said University of Minnesota mechanical engineering professor Uwe Kortshagen, inventor of the process for creating silicon nanoparticles and one of the senior authors of the study. “At this size, silicon’s properties change and it becomes an efficient light emitter, with the important property not to re-absorb its own luminescence. This is the key feature that makes silicon nanoparticles ideally suited for LSC applications.”

Using the silicon nanoparticles opened up many new possibilities for the research team.

“Over the last few years, the LSC technology has experienced rapid acceleration, thanks also to pioneering studies conducted in Italy, but finding suitable materials for harvesting and concentrating solar light was still an open challenge,” said Sergio Brovelli, physics professor at the University of Milano-Bicocca, co-author of the study, and co-founder of the spin-off company Glass to Power that is industrializing LSCs for photovoltaic windows “Now, it is possible to replace these elements with silicon nanoparticles.”

Researchers say the optical features of silicon nanoparticles and their nearly perfect compatibility with the industrial process for producing the polymer LSCs create a clear path to creating efficient photovoltaic windows that can capture more than 5 percent of the sun’s energy at unprecedented low costs.

“This will make LSC-based photovoltaic windows a real technology for the building-integrated photovoltaic market without the potential limitations of other classes of nanoparticles based on relatively rare materials,” said Francesco Meinardi, physics professor at the University of Milano-Bicocca and one of the first authors of the paper.

The silicon nanoparticles are produced in a high-tech process using a plasma reactor and formed into a powder.

“Each particle is made up of less than two thousand silicon atoms,” said Samantha Ehrenberg, a University of Minnesota mechanical Ph.D. student and another first author of the study. “The powder is turned into an ink-like solution and then embedded into a polymer, either forming a sheet of flexible plastic material or coating a surface with a thin film.”

The University of Minnesota invented the process for creating silicon nanoparticles about a dozen years ago and holds a number of patents on this technology. In 2015, Kortshagen met Brovelli, who is an expert in LSC fabrication and had already demonstrated various successful approaches to efficient LSCs based on other nanoparticle systems. The potential of silicon nanoparticles for this technology was immediately clear and the partnership was born. The University of Minnesota produced the particles and researchers in Italy fabricated the LSCs by embedding them in polymers through an industrial based method, and it worked.

“This was truly a partnership where we gathered the best researchers in their fields to make an old idea truly successful,” Kortshagen said. “We had the expertise in making the silicon nanoparticles and our partners in Milano had expertise in fabricating the luminescent concentrators. When it all came together, we knew we had something special.”

Source: University of Minnesota

 

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LG and Samsung Announce Quantum Dot TV: Market to Reach $9.6 BILLION by 2023


Hisense%20Quantum%20Dot%20ULEDLG announced quantum dot TV; quantum dot market forecast December 16, 2014. Today LG announced it’ll showcase its quantum dot TV at the upcoming CES 2015. We also expect Samsung to show quantum dot TV. Quantum dot could improve Liquid Crystal Display (LCD) dramatically in terms of color gamut, color accuracy and reducing power consumption.

QD-market-forecast-chart

Figure. Quantum dot display and lighting market forecast Source: Touch Display Research “Quantum dot display and lighting technologies and market forecast report”.

This is one of the biggest breakthrough technologies for LCD in recent several years. Now quantum dot LCD is challenging AMOLED. Touch Display Research surveyed many quantum dot suppliers and found that the quantum dot display component market surpassed $70 million in 2013.

We forecast that the quantum dot display and lighting component market will reach $9.6 billion by 2023. Touch Display Research will be at CES 2015 and report about all quantum dot displays and lighting.

Nano-Crystal (Quantum Dots) Boosted System Shows Doubled Light-Harvesting Ability


1-ACS Solar Band Gap nl-2014-03322a_0005Publication Date (Web): October 16, 2014

Conventional solar cells exhibit limited efficiencies in part due to their inability to absorb the entire solar spectrum. Sub-band-gap photons are typically lost but could be captured if a material that performs up-conversion, which shifts photon energies higher, is coupled to the device.

Recently, molecular chromophores that undergo triplet–triplet annihilation (TTA) have shown promise for efficient up-conversion at low irradiance, suitable for some types of solar cells. However, the molecular systems that have shown the highest up-conversion efficiency to date are ill suited to broadband light harvesting, reducing their applicability.

1-ACS Solar Band Gap nl-2014-03322a_0005

Here we overcome this limitation by combining an organic TTA system with highly fluorescent CdSe semiconductor nanocrystals. Because of their broadband absorption and spectrally narrow, size-tunable fluorescence, the nanocrystals absorb the radiation lost by the TTA chromophores, returning this energy to the up-converter. The resulting nanocrystal-boosted system shows a doubled light-harvesting ability, which allows a green-to-blue conversion efficiency of ∼12.5% under 0.5 suns of incoherent excitation. This record efficiency at subsolar irradiance demonstrates that boosting the TTA by light-emitting nanocrystals can potentially provide a general route for up-conversion for different photovoltaic and photocatalytic applications.

Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca, 20125 Milano, Italy
Optical Materials Engineering Laboratory, ETH Zurich, 8092 Zurich, Switzerland
Nano Lett., Article ASAP
DOI: 10.1021/nl503322a
Publication Date (Web): October 16, 2014
Copyright © 2014 American Chemical Society

New “gold nanocluster” Technology Revolutionizes Solar Power


QDOT images 6Scientists at Western University have discovered that a small molecule created with just 144 atoms of gold can increase solar cell performance by more than 10 per cent.

 

 

 

These findings, published recently by the high-impact journal Nanoscale, represent a game-changing innovation that holds the potential to take solar power mainstream and dramatically decrease the world’s dependence on traditional, resource-based sources of energy, says Giovanni Fanchini from Western’s Faculty of Science.

Fanchini, the Canada Research Chair in Carbon-based Nanomaterials and Nano-optoelectronics, says the new technology could easily be fast-tracked and integrated into prototypes of solar panels in one to two years and solar-powered phones in as little as five years.

“Every time you recharge your cell phone, you have to plug it in,” says Fanchini, an assistant professor in Western’s Department of Physics and Astronomy. “What if you could charge mobile devices like phones, tablets or laptops on the go? Not only would it be convenient, but the potential energy savings would be significant.”

The Western researchers have already started working with manufacturers of solar components to integrate their findings into existing and are excited about the potential.

“The Canadian business industry already has tremendous know-how in solar manufacturing,” says Fanchini. “Our invention is modular, an add-on to the existing production process, so we anticipate a working prototype very quickly.”

Mix id32807

Making nanoplasmonic enhancements, Fanchini and his team use “gold nanoclusters” as building blocks to create a flexible network of antennae on more traditional to attract an increase of light. While nanotechnology is the science of creating functional systems at the molecular level, nanoplasmonics investigates the interaction of light with and within these systems.

“Picture an extremely delicate fishnet of gold,” explains Fanchini explains, noting that the antennae are so miniscule they are unseen even with a conventional optical microscope. “The fishnet catches the light emitted by the sun and draws it into the active region of the solar cell.”

1-watchingnano

According to Fanchini, the spectrum of light reflected by gold is centered on the yellow colour and matches the light spectrum of the sun making it superior for such antennae as it greatly amplifies the amount of sunlight going directly into the device.

“Gold is very robust, resilient to oxidization and not easily damaged, making it the perfect material for long-term use,” says Fanchini. “And gold can also be recycled.”

It has been known for some time that larger gold nanoparticles enhance solar cell performance, but the Western team is getting results with “a ridiculously small amount” – approximately 10,000 times less than previous studies, which is 10,000 times less expensive too.

Explore further: Using solar energy to turn raw materials into ingredients for everyday life

Provided by University of Western Ontario

Nanotechnology to provide Cleaner Diesel Engines


Applications of Nanomaterials Chart Picture1It may seem paradoxical that a rare precious metal such as platinum is used in something as simple as smoky truck exhaust systems—nonetheless, this has always been a fundamental technological principle.

When it comes to diesel engine catalysts—i.e. the element responsible for cleansing exhaust fumes particles—platinum has unfortunately proved to be the only viable option, which has resulted in material costs alone accounting for half of the price of a diesel catalyst.

Such dependency on precious metals is both costly and unsustainable, which is why InnovationsFonden invested an impressive DKK 15 million—half of the total budget—in a project to find new catalyst materials based on nanotechnology.

The collaborative project involves Aarhus University, Danish Technological Institute, Dinex A/S tasked with production—and finally DTU, where will bring more than 25 years’ experience in experimental surface physics, nanotechnology and catalysis to bear.

“I have devoted myself exclusively to catalysts and surface physics since 1987. I am therefore excited by the prospect of my research finding a specific technological application,” says Ib Chorkendorff, who usually works with catalysts and nanomaterials at basic research level.

New catalysts

In essence, Aarhus University has developed a new way to manufacture catalysts and is now assessing the further development options that are opening up.

“Our idea is to try and make better catalysts for diesel engines than those currently available, and in particular, to find a viable alternative to platinum, which is, of course, a very expensive raw material,” says Ib Chorkendorff.

“We are focusing on nanoparticles because we want to maximize the surface area, but objects don’t like surfaces—two drops of water merge into one large drop to reduce surface energy, for example. The art is to create small reactive nanoparticles and keep them apart so they don’t merge together. The greater the surface area, the less material you require,” explains Ib Chorkendorff.

Each time you optimize the platinum surface, you save material and thus achieve greater effect at less cost.

Dinex A/S, the company looking to transform the research behind the new technology into new catalysts for the global market, has found it invaluable working with someone of Chorkendorff’s calibre:

“We believe that collaboration between the business sector and the research community is a win-win situation. Such partnerships hold huge untapped potential,” says Lars Christian Larsen, R & D Director, Dinex.

With the assistance of Ib Chorkendorff and the rest of the team, he hopes to achieve a 25% platinum reduction, which will rank Dinex among global leaders in catalyst production.

The project will be launched in the autumn, and in addition to Ib Chorkendorffs 25 years of experience and insight, DTU’s contribution will include a PhD student or a postdoc.

Article from DTUavisen No. 7, September 2014.

Source: Technical University of Denmark

Genesis Nanotech ‘News and Updates’ – September 9, 2014


Nano Sensor for Cancer 50006

Genesis Nanotech ‘News and Updates’ – September 9, 2014

Follow This Link: https://paper.li/GenesisNanoTech/1354215819#

Or by Individual Articles:

Transfer Printing Methods for Flexible Thin Film Solar Cells: Basic Concepts and Working Principles – ACS Nano (ACS Publications)

Nanotechnology to slash NOx and “cancerous” emissions

Tumor-Homing, Size-Tunable Clustered Nanoparticles for Anticancer Therapeutics – ACS Nano (ACS Publications)

New Detector Capable of Capturing Terahertz Waves at Room Temperature

Quotable Coach: Plug In And Participate – The Multiplier Mindset: Insights & Tips for Entrepreneurs

Genesis Nanotechnology – “Great Things from Small Things!”

10 Emerging Technologies That Will Change/ Have Changed (?) Your World


CNT multiprv1_jpg71ec6d8c-a1e2-4de6-acb6-f1f1b0a66d46LargerNote to Readers: It is interesting (To Us at GNT anyway) that the BOLD predictions for technology, should always be IOHO “re-visited”. What follows is the “Top 10 List” from 2004. 10 Years … How have the technology “fortune-tellers” done?!

 

 

10 Emerging Technologies That Will Change Your World

Technology Review unveils its annual selection of hot new technologies about to affect our lives in revolutionary ways-and profiles the innovators behind them.

Full Article Link Here: http://www2.technologyreview.com/featured-story/402435/10-emerging-technologies-that-will-change-your/

Technology Review: February 2004

With new technologies constantly being invented in universities and companies across the globe, guessing which ones will transform computing, medicine, communication, and our energy infrastructure is always a challenge. Nonetheless, Technology Review’s editors are willing to bet that the 10 emerging technologies highlighted in this special package will affect our lives and work in revolutionary ways-whether next year or next decade. For each, we’ve identified a researcher whose ideas and efforts both epitomize and reinvent his or her field. The following snapshots of the innovators and their work provide a glimpse of the future these evolving technologies may provide.

10 Emerging Technologies That Will Change Your World
Universal Translation
Synthetic Biology
Nanowires
T-Rays
Distributed Storage
RNAi Interference
Power Grid Control
Microfluidic Optical Fibers
Bayesian Machine Learning
Personal Genomics

Excerpt: Nanowires:

(Page 4 of 11)

PEIDONG YANG

Nanowires

Few emerging technologies have offered as much promise as nanotechnology, touted as the means of keeping the decades-long electronics shrinkfest in full sprint and transfiguring disciplines from power production to medical diagnostics. Companies from Samsung Electronics to Wilson Sporting Goods have invested in nanotech, and nearly every major university boasts a nanotechnology initiative. Red hot, even within this R&D frenzy, are the researchers learning to make the nanoscale wires that could be key elements in many working nanodevices.

“This effort is critical for the success of the whole [enterprise of] nanoscale science and technology,” says nanowire pioneer Peidong Yang of the University of California, Berkeley. Yang has made exceptional progress in fine-tuning the properties of nanowires. Compared to other nanostructures, “nanowires will be much more versatile, because we can achieve so many different properties just by varying the composition,” says Charles Lieber, a Harvard University chemist who has also been propelling nanowire development.

The World Of Tomorrow: Nanotechnology: Interview with PhD and Attorney D.M. Vernon


Bricks and Mortar chemistsdemoThe Editor interviews Deborah M. VernonPhD, Partner in McCarter & English, LLP’s Boston office.

 

 

 

Why It Matters –

” … I would say the two most interesting areas in the last year or two have been in 3-D printing and nanotechnology. 3-D printing is an additive technology in which one is able to make a three-dimensional product, such as a screw, by adding material rather than using a traditional reduction process, like a CNC (milling) process or a grinding-away process.

The other interesting area has been nanotechnology. Nanotechnology is the science of materials and structures that have a dimension in the nanometer range (1-1,000 nm) – that is, on the atomic or molecular scale. A fascinating aspect of nanomaterials is that they can have vastly different material properties (e.g., chemical, electrical, mechanical properties) than their larger-scale counterparts. As a result, these materials can be used in applications where their larger-scale counterparts have traditionally not been utilized.”

nanotech

Editor: Deborah, please tell us about the specific practice areas of intellectual property in which you participate.

 

 

Vernon: My practice has been directed to helping clients assess, build, maintain and enforce their intellectual property, especially in the technology areas of material science, analytical chemistry and mechanical engineering. Prior to entering the practice of law, I studied mechanical engineering as an undergraduate and I obtained a PhD in material science engineering, where I focused on creating composite materials with improved mechanical properties.

Editor: Please describe some of the new areas of biological and chemical research into which your practice takes you, such as nanotechnology, three-dimensional printing technology, and other areas.

Vernon: I would say the two most interesting areas in the last year or two have been in 3-D printing and nanotechnology. 3-D printing is an additive technology in which one is able to make a three-dimensional product, such as a screw, by adding material rather than using a traditional reduction process, like a CNC (milling) process or a grinding-away process. The other interesting area has been nanotechnology. Nanotechnology is the science of materials and structures that have a dimension in the nanometer range (1-1,000 nm) – that is, on the atomic or molecular scale.

A fascinating aspect of nanomaterials is that they can have vastly different material properties (e.g., chemical, electrical, mechanical properties) than their larger-scale counterparts. As a result, these materials can be used in applications where their larger-scale counterparts have traditionally not been utilized.

Organ on a chip organx250

I was fortunate to work in the nanotech field in graduate school. During this time, I investigated and developed methods for forming ceramic composites, which maintain a nanoscale grain size even after sintering. Sintering is the process used to form fully dense ceramic materials. The problem with sintering is that it adds energy to a system, resulting in grain growth of the ceramic materials. In order to maintain the advantageous properties of the nanosized grains, I worked on methods that pinned the ceramic grain boundaries to reduce growth during sintering.

The methods I developed not only involved handling of nanosized ceramic particles, but also the deposition of nanofilms into a porous ceramic material to create nanocomposites. I have been able to apply this experience in my IP practice to assist clients in obtaining and assessing IP in the areas of nanolaminates and coatings, nanosized particles and nanostructures, such as carbon nanotubes, nano fluidic devices, which are very small devices which transport fluids, and 3D structures formed from nanomaterials, such as woven nanofibers.

Editor: I understand that some of the components of the new Boeing 787 are examples of nanotechnology.

Vernon: The design objective behind the 787 is that lighter, better-performing materials will reduce the weight of the aircraft, resulting in longer possible flight times and decreased operating costs. Boeing reports that approximately 50 percent of the materials in the 787 are composite materials, and that nanotechnology will play an important role in achieving and exceeding the design objective. (See, http://www.nasc.com/nanometa/Plenary%20Talk%20Chong.pdf).

While it is believed that nanocomposite materials are used in the fuselage of the 787, Boeing is investigating applying nanotechnology to reduce costs and increase performance not only in fuselage and aircraft structures, but also within energy, sensor and system controls of the aircraft.

Editor: What products have incorporated nanotechnology? What products are anticipated to incorporate its processes in the future?

Vernon: The products that people are the most familiar with are cosmetic products, such as hair products for thinning hair that deliver nutrients deep into the scalp, and sunscreen, which includes nanosized titanium dioxide and zinc oxide to eliminate the white, pasty look of sunscreens. Sports products, such as fishing rods and tennis rackets, have incorporated a composite of carbon fiber and silica nanoparticles to add strength. Nano products are used in paints and coatings to prevent algae and corrosion on the hulls of boats and to help reduce mold and kill bacteria. We’re seeing nanotechnology used in filters to separate chemicals and in water filtration.

The textile industry has also started to use nano coatings to repel water and make fabrics flame resistant. The medical imaging industry is starting to use nanoparticles to tag certain areas of the body, allowing for enhanced MRI imaging. Developing areas include drug delivery, disease detection and therapeutics for oncology. Obviously, those are definitely in the future, but it is the direction of scientific thinking.

Editor: What liabilities can product manufacturers incur who are incorporating nanotechnology into their products? What kinds of health and safety risks are incurred in their manufacture or consumption?Nano Body II 43a262816377a448922f9811e069be13

Vernon: There are three different areas that we should think about: the manufacturing process, consumer use and environmental issues. In manufacturing there are potential safety issues with respect to the incorporation or delivery of nanomaterials. For example, inhalation of nanoparticles can cause serious respiratory issues, and contact of some nanoparticles with the skin or eyes may result in irritation. In terms of consumer use, nanomaterials may have different material properties from their larger counterparts.

As a result, we are not quite sure how these materials will affect the human body insofar as they might have a higher toxicity level than in their larger counterparts. With respect to an environmental impact, waste or recycled products may lead to the release of nanoparticles into bodies of water or impact wildlife. The National Institute for Occupational Safety and Health has established the Nanotechnology Research Center to develop a strategic direction with respect to occupational safety and nanotechnology. Guidance and publications can be found at http://www.cdc.gov/niosh/topics/nanotech.

Editor: The European Union requires the labeling of foods containing nanomaterials. What has been the position of the Food & Drug Administration and the EPA in the United States about food labeling?

Vernon: So far the FDA has taken the position that just because nanomaterials are smaller, they are not materially different from their larger counterparts, and therefore there have been no labeling requirements on food products. The FDA believes that their current standards for safety assessment are robust and flexible enough to handle a variety of different materials. That being said, the FDA has issued some guidelines for the food and cosmetic industries, but there has not been any requirement for food labeling as of now. The EPA has a nanotechnology division, which is also studying nanomaterials and their impact, but I haven’t seen anything that specifically requires a special registration process for nanomaterials.

Editor: What new regulations regarding nanotech products are expected? Should governmental regulations be adopted to prevent nanoparticles in foods and cosmetics from causing toxicity?

Vernon: The FDA has not telegraphed that any new regulations will be put into place. The agency is currently in the data collection stage to make sure that these materials are being safely delivered to people using current FDA standards – that materials are safe for human consumption or contact with humans. We won’t really understand whether or not regulations will be coming into place until we see data coming out that indicates that there are issues that are directly associated with nanomaterials. Rather than expecting regulations, I would suggest that we examine the data regarding nano products to optimize safe handling and use procedures.

Editor: Have there ever been any cases involving toxicity resulting from nano products?

Vernon: There are current investigations about the toxicity of carbon nano tubes, but the research is in its infancy. There is no evidence to show any potential harm from this technology. Unlike asbestos or silica exposure, the science is not there yet to demonstrate any toxicity link. The general understanding is that it may take decades for any potential harm to manifest. I believe my colleague, Patrick J. Comerford, head of McCarter’s product liability team in Boston, summarizes the situation well by noting that “if any supportable science was available, plaintiff’s bar would have already made this a high-profile target.”

Editor: While some biotech cases have failed the test of patentability before the courts, such as the case of Mayo v. Prometheus, what standard has been set forth for a biotech process to pass the test for patentability?

Vernon: There is no specified bright-line test for determining if a biotech process is patentable. But what the U.S. Patent and Trademark Office has done is to issue some new examination guidelines with respect to the Mayo decision that help examiners figure out whether a biotech process is patent eligible. Specifically, the guidelines look to see if the biotech process (i.e., a process incorporating a law of nature) also includes at least one additional element or step. That additional element needs to be significant and not just a mental or correlation step. If a biotech process patent claim includes this significant additional step, there still needs to be a determination if the process is novel and non-obvious over the prior art. So while this might not be a bright-line test to help us figure out whether a biotech process is patentable, it at least gives us some direction about what the examiners are looking for in the patent claims.

Editor: What effect do you think the new America Invents Act will have in encouraging biotech companies to file early in the first stages of product development? Might that not run the risk that the courts could deny patentability as in the Ariad case where functional results of a process were described rather than the specific invention?

Vernon: The AIA goes into effect next month. What companies, especially biotech companies, need to do is file early. Companies need to submit applications supported by their research to include both a written description and enablement of the invention. Companies will need to be more focused on making sure that they are not only inventing in a timely manner but are also involving their patent counsel in planned and well-thought-out experiments to make sure that the supporting information is available in a timely fashion for patenting.

Editor: Have there been any recent cases relating to biotechnology or nanotechnology that our readers should be informed about?

Vernon: The Supreme Court will hear oral arguments in April in the Myriad case. This case involves the BRCA gene, the breast cancer gene – and the issue is whether isolating a portion of a gene is patentable. While I am not a biotechnologist, I think this case will also impact nanotechnology as a whole. Applying for a patent on a portion of a gene is not too far distant from applying for a patent on a nanoparticle of a material that already exists but which has different properties from the original, larger-counterpart material. Would this nanosize material be patentable? This will be an important case to see what guidance the Supreme Court delivers this coming term.

Editor: Is there anything else you’d like to add?

Vernon: I think the next couple of years for nanotech will be very interesting. As I mentioned, I did my PhD thesis in the nanotechnology area a few years ago. My studies, like those of many other students, were funded in part with government grants. There is a great deal of government money being poured into nanotechnology. In the next ten years we will start seeing more and more of this research being commercialized and adopted into our lives. To keep current of developments, readers can visit www.nano.gov.

The Metropolitan Corporate Counsel
The Leading Resource For Corporate Counsel

As a leading publication in the corporate counsel community, MCC offers unique editorial content covering legal, regulatory, legislative and business developments, featuring original articles and interviews from experts at prestigious law firms, bar associations, accounting firms and legal service providers, as well as educators, business executives and high-level state, national and international officials.

 

Breaking the Space Charge Limit in Organic Solar Cells: Why It Matters


Hong Kong Organic SC srep06236-f1

Why It Matters – “Most importantly, the plasmonic-electrical concept will open up a new way to manipulate both optical and electrical properties of semiconductor devices simultaneously.”

” … Understanding the SCL (space charge limit) effect is important to manipulate transport, recombination, and extraction of photocarriers, which will significantly affect the power conversion efficiency (PCE) of OSCs. (Organic Solar Cells)”

As a fundamental electrostatic limit, space charge limit (SCL) for photocurrent is a universal phenomenon and of paramount importance for organic semiconductors with unbalanced photocarriers mobility and high exciton generation. Here we proposed a new plasmonic-electrical concept to manipulate electrical properties of organic devices including photocarriers recombination, transport and collection.

 

As a proof-of-concept, organic solar cells (OSCs) comprising metallic planar and grating electrodes are systematically investigated with normal and inverted device structures. Interestingly, although strong plasmonic resonances induce abnormally dense photocarriers around a grating anode, the grating-inverted OSC is exempt from space charge accumulation (limit) and degradation of electrical properties in contrast to the planar-inverted and planar-normal ones.

The particular reason is that plasmonically induced photocarriers redistribution shortens the transport path of low-mobility holes, which are collected by the grating anode. The work demonstrated and explained the SCL breaking with the plasmonic-electrical effect. Most importantly, the plasmonic-electrical concept will open up a new way to manipulate both optical and electrical properties of semiconductor devices simultaneously.

This work is supported by the General Research Fund (grants: HKU711813 and HKU711612E), the National Natural Science Foundation of China (NSFC)/Research Grants Council (RGC) grant (N_HKU709/12) and Ministry of Education (MOE)/Research Grants Council (RGC) (M-HKU703/12) from RGC of Hong Kong Special Administrative Region, China. This project is also supported in part by Collaborated Research Fund (CUHK1/CRF/12G) of RGC, NSFC grant (No. 61201122), and UGC of Hong Kong (No. AoE/P-04/08).

Abstract ** The complete referenced article is available here online at:

http://www.nature.com/srep/2014/140829/srep06236/full/srep06236.html

The space charge limit (SCL) effect is a universal phenomenon in semiconductor devices involving light emitting diodes, solar cells, and photodetectors1, 2, 3, 4, 5, 6, 7, 8, 9. It also sets a fundamental electrostatic limit in electrical properties of organic semiconductor devices with unbalanced photocarriers (electrons and holes) mobility and high exciton generation efficiency10, 11, 12, 13, 14. With the interesting features of low cost, low-temperature fabrication, semi-transparency, and mechanical flexibility, organic solar cell (OSC) is currently one of emerging optoelectronic devices and shows a bright outlook for green energy industry12, 13, 15, 16, 17, 18. Understanding the SCL effect is important to manipulate transport, recombination, and extraction of photocarriers, which will significantly affect the power conversion efficiency (PCE) of OSCs.

 

Hong Kong SC 2 srep06236-f1

 

Typically, the occurrence of SCL4 satisfies the following conditions: (1) unbalanced hole and electron mobility; (2) thick active layer; (3) high light intensity or dense photocarriers (electrons and holes) generation; and (4) moderate reverse bias. Compared to electron mobility, a low mobility of holes typically occurs in organic semiconductor devices depending on fabrication procedures19, 20, 21, 22 e.g. thermal annealing, solvent annealing, etc; and even occurs in the OSCs with robust active materials such as the polymer blend of poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM). To investigate SCL characteristics, the inverted OSC with a planar multilayered structure is taken as a representative example. In the planar-inverted OSCs, photocarriers will be generated at the region close to the transparent cathode, such as indium tin oxide (ITO), where incident light will first penetrate. The photogenerated holes with a low mobility will have to transport through the whole active layer, and finally reach the anode (see Figure 1(a)). SCL will occur if the length of active layer is longer than the mean drift length of holes, which is very short because of the low mobility. Meanwhile, holes pile up inside the device to a greater degree than electrons. In other words, positive space charges are accumulated due to the unbalanced photocarriers mobility and a long transport path of holes. As a result, the short-circuit current and fill factor of OSCs will drop significantly due to both the bulk recombination and space charge formation4, 7, 9, 23, 24. In this work, we will demonstrate the SCL breaking in the OSCs incorporating metallic (Ag or Au) nanostructures, which offers a novel route to eliminate the SCL effect in semiconductor devices.

(For the complete article see this link)

http://www.nature.com/srep/2014/140829/srep06236/full/srep06236.html

“Genesis Nanotechnology – Great Things from Small Things”

NIST Study: Why Quantum Dots Suffer from Fluorescence Intermittency


NIST 580303_10152072709285365_1905986131_nResearchers at the National Institute of Standards and Technology (NIST), working in collaboration with the Naval Research Laboratory, have found that a particular species of quantum dots that weren’t commonly thought to blink, do.

So what? Well, although the blinks are short—on the order of nanoseconds to milliseconds—even brief fluctuations can result in efficiency losses that could cause trouble for using to generate photons that move information around inside a quantum computer or between nodes of a future high-security internet based on quantum telecommunications.

Beyond demonstrating that the dots are blinking, the team also suggests a possible culprit.

Scientists have regarded indium arsenide and gallium arsenide (InAs/GaAs) quantum dots to be promising as single photon sources foruse in different future computing and communication systems based on . Compared to other systems, researchers have preferred these quantum dots because they appeared to not blink and because they can be fabricated directly into the types of semiconductor optoelectronics that have been developing over the past few decades.

QDOT images 3

The NIST research team also thought these quantum dots were emitting steady light perfectly, until they came upon one that was obviously blinking (or was “fluorescently intermittent,” in technical terms). They decided to see if they could find others that were blinking in a less obvious way.

While most previous experiments surveyed the dots in bulk, the team tested these dots as they would be used in an actual device. Using an extremely sensitive photon autocorrelation technique to uncover subtle signatures of blinking, they found that the dots blink over timescales rangingfrom tens of nanoseconds to hundreds of milliseconds. Their results suggest that building photonic structures around the quantum dots—something you’d have to do to make many applications viable—may make them significantly less stable as a light source.

“Most of the previous experimental studies of blinking inInAs/GaAs quantum dots looked at their behavior after the dots have been grown but before the surrounding devices have been fabricated,” says Kartik Srinivasan, one of the authors of the study. “However, there is no guarantee that a quantum dot will remain non-blinking after the nanofabrication of a surrounding structure, which introduces surfaces and potential defects within 100 nanometers of the quantum dot. We estimate the radiative efficiency of the quantum dots to be between about 50 and 80 percent after the photonic structures are fabricated, significantly less than the 100 percent efficiency that future applications will require.”

According to Marcelo Davanço, another author of the study, future work will focus on measuring dots both before and after device fabrication to better assess whether the fabrication is indeed a source of the defects thought to cause the blinking. Ultimately, the authors hope to understand what types of device geometries will avoid while still efficiently funneling the emitted photons into a useful transmission channel, such as an optical fiber.

The NIST Center for Nanoscale Science and Technology (CNST) is a national nanotechnology user facility that enables innovation by providing rapid access to the tools needed to make and measure nanostructures. Researchers interested in accessing the techniques described here or in collaborating on their future development should contact Kartik Srinivasan.

Explore further: Quantum dots provide complete control of photons

More information: M. Davanço, C. Stephen Hellberg, S. Ates, A. Badolato and K. Srinivasan. “Multiple time scale blinking in InAs quantum dot single-photon sources.” Phys. Rev. B 89, 161303(R) – Published 16 April 2014.