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Quantum Dots with Built-in Charge Could Lead to Highly Efficient Solar Cells

When you see 45 percent energy conversion efficiency for solar cells, you stop and take notice.

The story of nanotechnology in solar cells over the last decade has often been about pushing energy conversion efficiency higher and higher while dragging prices lower and lower. It hasn’t always been easy to sustain that dual-pronged attack.

Certainly, quantum dots have been looked at by researchers in this area as a possibility for achieving high conversion efficiency at a lower cost.

But I had no reason to expect that the use of quantum dots in solar cells would yield 45 percent conversion efficiency. Nonetheless that’s the figure I saw when University of Buffalo, in collaboration with both the Army Research Laboratory and the Air Force Office of Scientific Research,  announced a way of embedding charged quantum dots into solar cells that allows the cells to harvest infrared light.

The research, which was originally published in the ACS journal Nano Letters last May, used selective doping of some of the quantum dots so they have a built-in charge that repels incoming electrons. This in turn forces the electrons to travel around the quantum dots.

As the abstract explains: “We found that the quantum dots with built-in charge (Q-BIC) enhance electron intersubband quantum dot transitions, suppress fast electron capture processes, and preclude deterioration of the open circuit voltage in the n-doped structures. These factors lead to enhanced harvesting and efficient conversion of IR energy in the Q-BIC solar cells.”

The three University of Buffalo researchers behind this work—Vladimir Mitin, Andrei Sergeev and Nizami Vagidov—have spun-out a company called Optoelectronic Nanodevices LLC that presumably will attempt to commercialize this technology.

Can a New Public Private Partnership Be the Spur to Give Nanotechnology its Industrial Push?

The estimated $10 billion the US Federal government has invested in nanotechnology over the last decade was all intended to create a new economic stimulus for the US economy.  The plan was that nanotechnology would be a new source of jobs in the US and a partial remedy for the loss of its manufacturing base.

However, during that 10-year period there has been a fair amount of disappointment and frustration at what nanotechnology promised  and what it in fact delivered in economic terms.

Frankly, this kind of reaction was inevitable after investors and business types were still hung over from the Internet bubble bursting.

Seven to ten years of long-term investment just did not work with the funding mechanisms--like venture capital--that had fueled the Internet’s development.  And it seemed no one could really come to terms with this. So significant has been this funding gap that I have argued that it has likely been the most important story about nanotechnology over the last decade.

While I have expressed my doubts about Russia’s nanotechnology initiative, I have admired their decision to not only fund basic research but set up a funding mechanism that can move basic research into products and commercialization.

Now I have learned from a piece from Scott E. Rickert over at Industry Week that the US has established a new public/private consortium called the Advanced Manufacturing Partnership (AMP) that will invest more than $500 million in moving nanotechnology from the lab to the fab. President Barack Obama announced the AMP back in June 2011 and at the end of December 2011 plans were announced to establish a new office within the Department of Commerce to oversee the AMP.

Rickert in his piece breaks down how that half-a-billion dollars will be allocated:

  • $300 million in domestic manufacturing in critical national security industries. That includes high-efficiency batteries and advanced composites —where nanotech leads.
  • $100 million for the research, training and infrastructure to develop and commercialize advanced materials at twice the speed and a greatly reduced price.
  • $12 million from the Commerce Department for an advanced manufacturing technology consortium charged with streamlining new product commercialization.
  • $24 million from the Defense Department for advances in weaponry and programs to reduce development timetables that enable entrepreneurs get into the game.
  • $12 million for consortia to tackle common technological barriers to new product development—the way earlier partnerships approached nanoelectronics
  • A group of the nation's top engineering schools will collaborate to accelerate the lab-to-factory timetable with AMP connecting them to manufacturers.

While I am not entirely clear on how the $300 million will be spent on “domestic manufacturing in critical national security industries”, I do hope that it will bridge that funding gap for companies that don’t want another SBIR grant or can’t get one, but need capital to go on to an industrial scale.

My concern is that a small company that has spun itself out from a university, developed some advanced prototypes, lined up their market, and picked their management group still need by some estimates somewhere in the neighborhood of $10 to $30 million to scale up to being an industrial manufacturer of a product.

That means that $300 million could start up anywhere from 10 to 30 companies. Not exactly the next industrial revolution.

I more or less agree with Rickert’s conclusion that the AMP should remain focused on private investment. But perhaps there needs to be a bigger priming of the pumps to make the investment more appealing to the private sector. When capital can be invested in derivatives and credit swap defaults that provide huge returns, breaking even after 5-10 years is not as appealing as one might think.

Carbon Nanotubes Get a New and Simple Bulk Sorting Process

Recently researchers at the Lawrence Berkeley National Laboratory, Stanford University, and the University of California Davis devised methods for sorting single-walled carbon nanotubes (SWNTs) so that semi-conducting and non-conducting SWNTs are separated. One obvious application is artificial skin.

This has long been a bottleneck in using SWNTs for electronics applications and it seems that dam has broken because now researchers at the London Centre for Nanotechnology at Imperial College London, UK, have also developed a simple separation solution for SWNTs.

Previous methods for separating nanotubes have been fantastically expensive—billions of pounds per kilo, as Milo Shaffer, head of the London Centre, notes in an interview with Chemistry World.

In contrast, the method that the London researchers developed should allow for bulk separation at an industrial scale. But cautious optimism seems called for at this point.

“There are many different methodologies in the literature that can achieve separation but the work here has the additional benefit of being potentially scalable,” says Karl Coleman, a nanotechnologist at the University of Durham, UK, who was also quoted in the article. “There is still plenty to be done as, in the grand scheme of things, the work still discusses milligrams and it remains to be seen whether you can use this methodology for kilograms.”

This line of research began after researchers at the University College London, UK observed that Buckminster fullerenes dissolved in ammonia. The two labs then collaborated on finding a separation method for SWNTs by seeing what would happen when they mixed SWNTs with sodium-ammonia solution.

This mixture results in what is described as an ammonia solution of sodium “nanotubide”. The next step is to remove the ammonia from the mixture, which leaves behind a dry powder of the nanotubide salt. When dry dimethylformamide is added to this nanotubide salt, a portion of immediately dissolves. The portion that dissolves is the part that contains the metallic SWNTs.

What this presents is the possibility of developing a large-scale separation method that relies just on the different electronic characteristics of the SWNTs and eliminates the need for centrifugation. This method could find itself fairly quickly adopted into commercial usage—Chemistry World also reports that Shaffer’s team has already licensed the technology to the industrial gas company, Linde.

Are We Witnessing an "Axis of Evil" in Nanotech?

I imagine that if you want to send shivers down the spine of a US diplomat, you would simply mention either Venezuela or Iran.

In case you missed the last decade, the bellicose rhetoric that goes on between the US and both Venezuela and Iran seems to get periodically ratcheted up. Last week may have been no exception, but with a bit of a new wrinkle.

If perhaps your role in the US government is to oversee the development of nanotechnology, then you may have received a panicked call from someone in the State Department last week asking how the US is doing in the field, after it was announced that Venezuela and Iran would expand their cooperation in nanotechnology.

In addition to flaunting their capabilities in uranium enrichment, Iran has been promoting its capabilities in nanotechnology of late, and as it turns out they are just as capable as Western countries in over-hyping their capabilities.

While TNTLog may have deemed Iran’s nanotechnology capabilities that of a “world-class player", I certainly have my doubts. In fact Iran’s nanotech capabilities only appear impressive if you add a very strong qualifier: “considering”.

Yes, considering the years of sanctions and the isolation of Iranian scientists from the rest of the world, it is indeed impressive that they have managed much of a nanotechnology initiative at all.

But outside of this recent announcement, I admit to not having heard one word about nanotechnology in Venezuela. Certainly Venezuela with its recent oil riches fits the profile of a government that can pursue any line of research it wishes without much concern about what its population would like.

After doing a little background research on this story, it seems the Venezuelan and Iranian leaders initially forged this nanotechnology agreement last year, at which time the Venezuelans acknowledged that they didn’t have much of background in the field.

"We travelled to Iran to visit this festival [Nanotechnology Festival in Iran on the 25-29 October 2010] and sign MoUs of cooperation within the scope of nanotechnology study affairs because Venezuela is at the preliminary stages in nanotechnology and the researches of Iranian experts could be useful in helping Venezuela to develop nanotechnology", said Guillermo Barrerto the CEO of Science and Technology Center at Venezuelan Ministry of Science, according to the Iran Nanotechnology Initiative Council press release on the MoU with Venezuela.

You have to feel a bit of sympathy for Venezuela in that they are newbies to the field and they are relying on a country whose developments in nanotechnology are only impressive when one adds the qualifier: considering. It would seem for both countries, it's not a relationship that is going to do much to further either one in their nanotechnology research.

Magnetic Nanoparticles Lead to a New Class of Composites

How can you make a material that is simultaneously strong, flexible and light? The answer has long been advanced composites that combine plastics, metals and ceramics to get the best characteristics out of each of them.

But achieving a balance between these materials' qualities of strength, flexibility and lightness is difficult to come by and often comes down to being able to manipulate the various materials into the perfect orientation to each other.

Researchers at ETH-Zürich have developed a process that gives them a far greater control over that orientation than ever before. The result is an entirely new class of composite that mimics the precise layering seen in nature's abalone seashell.

The idea was simple. Why not get the materials to move to where you wanted them to go by the use of magnetic force, not unlike a bar magnet orienting iron fillings? However, the obvious problem is that not all materials used in composites are magnetic.

The researchers, who published their work in the January 13th issue of the journal Science in an article entitled "Composites Reinforced in Three Dimensions by Using Low Magnetic Fields," overcame this obstacle by adding a small amount of magnetic nanoparticles to the nonmagnetic materials.

The researchers discovered that this process of adding magnetic nanoparticles only works with stiff elements in the micrometer size range, which just so happens to overlap with the sizes the composite industry uses.

One would have to believe that this research will quickly find itself in commercial use as the ETH-Zürich researchers are continuing this work in collaboration with composite companies to get this straight into industrial processes.

The material will certainly get early adopters in any industry in which strong, light and flexible are sought after characteristics. While aerospace immediately comes to mind, the growing market of wind turbines should likely be another.

The addition of nanomaterials into advanced composites no longer seems like a mere marketing ploy,  but is increasingly becoming a way of actually making composites stronger or imbuing them with greater functionality. Perhaps nanocomposites are finally coming into their own.

Largest Quantum Computer Calculation to Date—But Is It Too Little Too Late?

After erring on the side of caution—if not doubt—when IEEE Spectrum cited D-Wave Systems as one of its “Big Losers” two years ago,  it seems that there was a reversal of opinion within this publication back in June of last year when Spectrum covered D-Wave’s first big sale of a quantum computer with an article and then a podcast interview of the company's CTO.

In the job of covering nanotechnology, one develops—sometimes—a bit more hopeful perspective on the potential of emerging technologies. Basic research that may lead to applications such as quantum computers get more easily pushed up in the development cycle than perhaps they should. So, I have been following the developments of D-Wave for at least the last seven years with a bit more credence than Spectrum had offered the company earlier.

In the continuing expansion of the company’s credibility in the development of quantum computers, D-Wave Systems has published a paper [pdf] in which they demonstrate an 84-qubit calculation of the notoriously difficult to calculate Ramsey numbers.

As the paper published in Cornell University’s arXiv journal states: “This computation is the largest experimental implementation of a scientifically meaningful quantum algorithm that has been done to date.”

The D-Wave researchers were able to complete this calculation in 270 milliseconds. This is a far cry from the much-ballyhooed ability of a quantum computer to factor the number 15.

But as impressive as this may sound, the blog Next Big Future conducted an interview with D-Wave’s CTO Geordie Rose just last month  in which Rose contends that the papers the company publishes are about two years behind where the company actually is in its research.

In Brian Wang's interview with D-Wave’s Rose, there's a discussion of the company’s new 512-qubit chip that should be, according to their calculations, 1000 times faster than the 128-qubit chips that D-Wave is currently working with.

As we learned from Steven Cherry’s podcast with Rose back in June, D-Wave was able to secure the $10-million sale of its hardware and software support so that Lockheed Martin could tackle some of their more difficult optimization problems.

So, it would seem optimization problems have become the measure by which D-Wave calculates how much more effective doubling the number of qubits on a chip can be in solving problems.

From the Next Big Future piece: “One application of the D-Wave system is for the optimization problem of creating treatment plans for cancer radiation treatment based on a 3D body scan. This treatment plan takes 1 week using the 128-qubit system but minutes with the 512-qubit system.”

While it may seem that D-Wave is on irreversible upward technological slope, one problem indicated in the Next Big Future interview is that capital may be beginning to dry up.

If so, it would seem almost ironic that after years of not selling anything and attracting a lot of capital, D-Wave would make a $10-million sale and then not be able to get any more funding.

But alas this is the sometimes topsy-turvy world of applying capital at the right time and in the right amount to emerging technologies.

This article was edited on 12 January 2012.

New Form of Graphene Opens up Applications in Thermal Conductivity for Electronics

Much has been made of how graphene’s lack of an inherent band gap holds it back in electronics applications.

But there are a couple of flaws in this argument. For one, not all would-be applications require the band gap seen in silicon-based materials. And what if there is actually more than one type of graphene?

Researchers at the University of Calfornia Riverside, in collaboration with researchers from The University of Texas at Austin, The University of Texas at Dallas and Xiamen University in China have in fact developed a new form of graphene whose purpose makes its lack of a bandgap irrelevant.

The researchers, led by Aelxander Balandin, a professor of electrical engineering at UC Riverside, and Professor Rodney S. Ruoff of UT Austin, have isotopically engineered graphene so it that has concentrations of 99.99 percent 12C (carbon) as opposed to the naturally occurring graphene that is found in concentrations of 98.9 percent 12C and 1.1 percent 13C.

What difference does 1 percent make? In a paper ("Thermal conductivity of isotopically modified graphene") published in the 8 Jan online version of the journal Nature Materials, the team reported that the slight variation in graphene's composition that they were able to achieve using chemical vapor deposition yielded a material that had remarkable heat dissipation qualities.  They say that the isotopically engineered graphene should should be useful in heat removal applications in a number of electronics applications as well as in photovoltaics.

“The important finding is the possibility of a strong enhancement of thermal conduction properties of isotopically pure graphene without substantial alteration of electrical, optical and other physical properties,” said Balandin in the UC Riverside press release. “Isotopically pure graphene can become an excellent choice for many practical applications provided that the cost of the material is kept under control.”

Importantly, the proposed applications do not call for graphene to replace silicon in the integrated circuit of the future, but for its use in the interconnects and thermal spreaders within computers or in transparent electrodes in photovoltaics.

Still, it's important to remember that while application proposals are intriguing at this stage, this is basic research. As Balandin remarks: “The experimental data on heat conduction in isotopically engineered graphene is also crucially important for developing an accurate theory of thermal conductivity in graphene and other two-dimensional crystals.”

Graphene Nanoribbons Get Super Computerized

About a year-and-a-half ago, researchers at EMPA and the University of Bern in Switzerland along with those from the Max Planck Institute for Polymer Research devised a method for growing from the bottom up a ribbons of graphene only a few nanometers wide.

In the time that has elapsed since then, researchers around the world have started to examine the material, and now scientists at Rensselaer Polytechnic Institute have focused one of the world’s most powerful supercomputers on it to uncover its properties.

What the Rensselaer researchers discovered was graphene nanoribbons when segmented take on various surface structures dubbed “nanowiggles” and that these structures produce different magnetic and conductive properties.

It is expected that the findings, which were published in the journal Physical Review Letters in a paper titled “Emergence of Atypical Properties in Assembled Graphene Nanoribbons”,  should enable others to pick characteristics of the graphene nanostructure and thereby customize the material to meet the requirements of a particular application.

“Graphene nanomaterials have plenty of nice properties, but to date it has been very difficult to build defect-free graphene nanostructures. So these hard-to-reproduce nanostructures created a near insurmountable barrier between innovation and the market,” said Vincent Meunier, the Gail and Jeffrey L. Kodosky ’70 Constellation Professor of Physics, Information Technology, and Entrepreneurship at Rensselaer in a press release from the Institute covering the research. “The advantage of graphene nanowiggles is that they can easily and quickly be produced very long and clean.”

One of the intriguing bits was that in the researchers’ computational analysis of the nanowiggles they discovered that they produce highly varied bandgaps. According to Meunier, this should allow for the tuning of the bandgap of the material to fit a certain application.

"We have created a roadmap that can allow for nanomaterials to be easily built and customized for applications from photovoltaics to semiconductors and, importantly, spintronics,” said Meunier.

Why is Russia Hot on Molecular Nanotech and the US Not?

Proponents of molecular nanotechnology (MNT) often point to the backroom politics back at the turn of the century that relegated ideas of nanobots and tabletop factories to the margins of nanotechnology’s development in the United States. Instead what we saw was the rise of material science on the nanoscale become the darling of research funding. Or so the story goes.

But not to worry, the US is not the only country on the planet. The father of MNT (or, if you prefer, advanced, atomically precise nanotechnology), Eric Drexler, recently discovered this when he attended Rusnanotech 2011 and received an extremely warm reception to the ideas of MNT.

I say, well done. It’s about time. Just because the US government decided that it would make more sense to fund an evolution of technology that could show benefits in a few short years rather than a few short decades, doesn’t mean that funding for that line of research doesn’t exist.

I have often said that if the MNT community wanted to get funding, then they should propose physical experiments and go out and secure the funding as Philip Moriarty did. With successful physical experimentation--as opposed to merely successful computer modeling--this would open the way to new experiments and new funding.

Perhaps an inch-by-inch method was not what the MNT community wanted to hear when the distances that needed to be covered were so great, but it certainly seems better than sitting down and complaining about one's predicament.

But as you look at this story of Russia’s interest in MNT the question inevitably arises: Why would Russia be so keen on MNT and the US so uninterested?

Backroom deals notwithstanding, the forms of government in the US and Russia are quite different.

I recently heard it argued that if “no taxation without representation” is true, then so is its inverse: no representation without taxation.

In countries where the leadership is funded by the exploitation of the local natural resources (like fossil fuels), it is unnecessary for that leadership to levy taxes on its citizens for its revenues and therefore doesn’t need to engage in the messy business of giving them any representation. The leadership can just do whatever they want without fear of retribution at the ballot box.

Russia does have some form of elections but it doesn’t appear to be so sensitive to the electorate that the idea of spending $10 billion of the electorate’s tax money and having little to show for it except some far-off promises would make much of a difference to their political careers.

I would suggest to MNT proponents that they should go around to the countries of the world that have a glut of cash and managed to get that money without tax revenues and propose research projects that have gone unfunded to date. Time to start drawing up those physical experiments.

With Science and Patience, Lawsuits against Nanotechnology Are Avoidable

Just before the holiday week, I read the discouraging news that a consumer group had filed a lawsuit against the Food & Drug Administration (FDA) regarding risks from the use of nanomaterials in products.

It seems that NGOs like the International Center for Technology Assessment (ICTA), inspired by their half-informed self-righteousness, somehow believe that lawsuits against the US government (the defense costs taxpayers will have to pay) is somehow helpful in either protecting consumers or determining the toxicity of nanomaterials that make up part of the material matrix of highly regulated products.

I mean the argument appears ridiculous on its surface. Basically, the ICTA believes that the FDA has been “unlawfully” delaying its decision on the safety of products that contain nanomaterials after the ICTA and other NGOs filed a petition in 2006.

How to explain the time it takes to get this sorted? Let’s see, with the elements contained in the periodic table we know the toxicity of the materials contained within it and the toxicity of the compounds when you mix these elements together. But what is being asked at this point is to reinvent the periodic table so that elements that have long-been considered benign need to be considered potentially toxic in their nanoscale form. Does any fair-minded person believe this constitutes heel dragging or an unlawful delay?

I must say I really enjoy how the NGOs always refer to a growing body of evidence about the toxicity of nanomaterials in products. They are masters this kind of rhetorical flourish, except when the tables are turned.

Despite my cynical appreciation of their manipulation of the media, I challenge them to show me one conclusive study that shows a product containing nanomaterials in a matrix has harmed anybody. You know, a tennis racquet or bicycle frame containing carbon nanotubes that causes sickness, or, dare I say, their favorite target: sunscreens that make people sick.

Just to anticipate their response, this is not the same as a nanomaterial in its free-floating form in which some nanomaterials have reportedly caused harm to workers. While this particular study I linked to here should be a cause of concern and a spur to further research, it has been revealed to have serious flaws in its science, and, most importantly, does not refer to nanomaterials that have been fixed into a larger material matrix.

My concern here is that all this bluster and self-satisfied finger pointing doesn’t manage to get us one step closer to determining whether nanomaterials when fixed into a material matrix are any more likely to be toxic to consumers than the bromine and PVC in your computer.

I want to know. And I would prefer that our tax dollars be spent on conducting that research to find out rather than being used to defend one of our government agencies from a lawsuit that doesn’t appear to have legs, but has kept the press occupied.



IEEE Spectrum’s nanotechnology blog, featuring news and analysis about the development, applications, and future of science and technology at the nanoscale.

Dexter Johnson
Madrid, Spain
Rachel Courtland
Associate Editor, IEEE Spectrum
New York, NY
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