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High Energy-Conversion Rates for Dye-Sensitized Solar Cells Made Easier

Earlier this year I had the opportunity to do an interview with the discover of dye-sensitized solar cells (DSSCs), Michael Grätzel, in which he indicated that we should expect to see DSSCs capable of 10% conversion efficiency mass produced quite soon.

This is pretty impressive since Sony only demonstrated a module capable of 10% conversion efficiency in 2010.

But, according to some researchers a the Chinese Academy of Sciences, reaching this high conversion efficiency comes with the high price tag of needing resource-limited materials such as ruthenium. So the researchers, led by Yu Bai, have developed a method by which they can attain those efficiency levels with DSSCs without the use of ruthenium.

The research, which was published in the journal of the American Chemical Society,  used an all-organic dye that can be used with cobalt in the place of the ruthenium.

To replace the use of ruthenium dyes researchers have been experimenting with so-called ‘push-pull’ dye sensitizers, which are molecules that contain “electron-accepting and –donating groups linked together by a conjugated bridge.”

The researchers took the push-pull dye sensitizers that had been tried thus far and incorporated an aromatic–sulfur bridging group. What resulted was a push-pull dye that reached an energy conversion efficiency of 9.4%, breaking the record for ruthenium-free DSCs just slightly behind the best ruthenium-based systems.

If this method can be incorporated into the mass production of DSSCs, it's likely the economics of this alternative solar cell could become even more attractive.

Balancing between Skepticism and Optimism in Nanotech

Sometimes the seeming conflict between the overflowing optimism for nanotechnology and then the biting skepticism aimed at it creates confusion in its wake. 

The skepticism surrounding nanotechnology in no small part stems from the belief—as Tim Harper points out—that a new iPhone app constitutes an emerging technology. When people confuse the next generation of an iPod with developing a material that will keep Moore's Law progressing for the next 25 years, there's likely to be some disappointment in nanotechnology.

Plus, isn’t disappointment almost assured when it seems the overriding sentiment within capital markets is “Why bother with hard to understand, risky, expensive and long term stuff like nanotechnology when it only takes a couple of guys with a few laptops to create the next Facebook – and you’ll know whether it will work in 18 months rather than 5 years.”

Indeed. This is why we are seeing the rise of sovereign investment organizations as they come to realize that waiting five years but potentially employing 500 people might make better sense in terms of economic development than employing five people within just a year-and-a-half.

There have been some strong examples within the US of government committing itself to investing in the commercialization of nanotechnology, such as what we have seen in the State of New York

But mainly we have seen that developing economies around the world are ready to step in and make that investment while major economies have waited on the sideline expecting capital markets to fill the gap.

From this state of affairs, one can’t help but wonder whether the inefficiency of markets may be depriving us of needed technological developments that many seem to think are as inevitable as the next iteration of the iPhone, but simply aren’t.

Harper recognizes this shortsightedness in his interview with the Spanish version of Technology Review

And this is certainly a conversation I have had with him before in our nearly ten-year association, but now I recognize a slight new wrinkle in his line of thinking.

It would seem that when he mentions “the creation of shared public-private responsibility for their (emerging technologies) development” as a means for realizing the potential of developed technologies he is not just talking about investment capital, but something more along the lines of public engagement to drive technological development beyond merely the enrichment of the developers.

To Harper it would now seem that the input of the public on what we should be doing with nanotechnology to improve our lives and the planet needs to become integral into how we can best exploit the technology.

Nurturing Basic Nanotech Research for Others to Enjoy the Fruit

It seems the past decade of the United States—along with parts of Europe and Asia—pouring money into nanotechnology research, which led to a few fledgling nanotechnology-based businesses, is finally paying off…for Russia.

Russia, through its RusNano investment organization, is picking up small nanotechnology start-ups from around the world at attractive prices—after other countries have invested billions in supporting the basic research that made some of the companies possible.

The latest announcement is that RusNano will be investing US $25 million in BIND Biosciences and $25 million in Selecta Biosciences, which, according to the RusNano press release, accounts for a total RUSNANO investment of $50 million within the total financing rounds of $94.5 million in the two companies combined.

In the cases of these two companies, I really don’t know to what extent their initial technology was funded or supported by the U.S. government, and I wouldn’t blame them a bit if it was significant. Businesses need capital just to get to production and then later to expand. It hardly matters where it comes from as long as they can survive another day.

We got a pretty stark reminder of this last summer when United Kingdom–based Nanoco let it be known on the pages of the Financial Times that it was fed up with getting no support from the UK government and was open to moving to any country that provided financial support.

It seems that many governments around the world are supportive of basic nanoscientfic research, especially when it involves the construction of a new lab. But when it involves the $25 to $50 million needed to take an advanced prototype into full-scale production, it seems the feeling is that’s the role of market capital.

Indeed it would be if capital were invested in things other than credit-swap defaults. But we know now that it isn’t

So, a country like Russia can set up an investment organization that focuses on nanotechnology and go around the world picking up struggling nanotech start-ups, like Plastic Logic

Here we are 10 years into a massive effort in both time and money to create a new spur to the U.S. economy and just as it’s about to bear fruit we let the crop rot on the vine and let our neighbor buy the entire stock for a song.

I think someone should wake up and realize market capital is not being invested in long-term investments like manufacturing goods with nanomaterials and that sovereign capital from countries like Russia—and they are not alone—are making up the difference. 

Russia Claims Revenues of One-Third-of–a-Billion Dollars in Nanotech This Year

It’s that time of year: RusNano is holding its annual nanotechnology conference.

This year, Dmitry Medvedev, instead of offering up a keynote address, has convened the 27th meeting of his modernization committee

The committee, whose charge it is “to monitor and promote the technological modernization of the economy at the executive level,” will review the status of the nanotechnology sector.

One of the first bits of interesting news to come out of the meeting is that: “In 2011, RusNano has earned about 10 billion rubles (US $312 million) on manufacturing products using nanotechnology—nearly half of the state corporation's total turnover."

I take the phrase “earned” as meaning revenues rather than profits. Taking RusNano's market estimates with a grain of salt has made sense in the past

We should expect these estimates to be fairly conservative, however, ever since Anatoly Chubais, RusNano's chief, got fed up with bogus market numbers he was seeing and decided that RusNano was going to track its own development

There is no doubt that this year RusNano loosened its purse strings and made a number of investments that may, or may not, be accounting for the $312 million this year. 

But if, as the Moscow Times article indicates, much of the revenue came from “specialized coatings to protect aluminum,” it does sound tantalizingly close to what we might expect from the memorandum of understandings RusNano and Toyota Tsusho and Alcoa signed earlier this year. 

I have to say though, no matter how you look at it, over $300 million in revenues is pretty impressive for a project that has really only existed for three years. 

Carbon Nanotubes Enable First Step Toward Artificial Skin

Researchers at Stanford University have devised a method by which they can spray single-walled carbon nanotubes (SWNTs) onto a thin layer of silicone and create a flexible and stretchable pressure sensor.

The researchers, led by Zhenan Bao, associate professor of chemical engineering, published their work in the journal Nature Nanotechnology this week under the title "Skin-like pressure and strain sensors based on transparent elastic films of carbon nanotubes."

"This sensor can register pressure ranging from a firm pinch between your thumb and forefinger to twice the pressure exerted by an elephant standing on one foot," said Darren Lipomi, a postdoctoral researcher in Bao's lab, who is part of the research team, in the Stanford article covering the research.

The researchers discovered that when they sprayed SWNTs onto silicone, the SWNTs naturally formed themselves into clumps, or “nanobundles.” When the silicone was initially stretched, those “nanobundles” aligned themselves in the direction of the stretching. On release, the nanobundles form into “nanosprings,” which in the silicone material act as electrodes.

"After we have done this kind of pre-stretching to the nanotubes, they behave like springs and can be stretched again and again, without any permanent change in shape," Bao is quoted as saying in the article.

The remarkable bit is that after the initial stretching forms the SWNTs into nanosprings, they can undergo numerous stretches without losing their electrical conductivity.

The initial aim of the research was looking not for high sensitivity, but instead to exploit the characteristics of transparency and its flexibility. However, according to Bao, they need only make some changes to the surface of the electrodes to increase its sensitivity.

A video that accompanied the Stanford press release on this story (see below) provides some of the application potential for the use of the material as an artificial skin both for robotics and artificial limbs for amputees.

With a Carbon Nanotube Glut, What Do You Do with Them?

While I was attending the EuroNanoForum 2011 conference earlier this year, I ran into an old acquaintance who works at a national nanotechnology laboratory.

He told me the tale of how a large, multinational company that produces multi-walled carbon nanotubes (MWNTs) approached the organization, wanting to pitch some ideas on how it could use carbon nanotubes. It came down to the company inventing uses for the MWNTs so it could get rid of the stuff.

The reason for desperate acts like this is that carbon nanotube producers have been on a capacity increase binge for the last few years without demand increasing, leaving the market for the stuff oversupplied to say the least.

Based on some analysis I have seen, the low, spot-pricing for MWNTs has dropped from $700/kg in 2006 to below $100/kg in 2009—and the price is expected to go down further, reaching $50/kg by next year. But truth be told, nobody buys raw carbon nanotubes. There is no market for them. Instead the market consists of sales of dispersions, master batches, and pre-pregs.

It is with this backdrop that I glanced over at a Spotlight piece in Nanowerk, entitled: “Global carbon nanotubes market—industry beckons.”

Well, if the author meant that MWNT producers are beckoning for someone to buy their glut of inventory, that title might make sense. But I don’t think that’s what he was driving at.

One could make the argument that the precipitous drop in pricing for MWNTs has made it a more attractive material, so we may be experiencing a slight shift to market pull as opposed to technology push. But let’s be serious. MWNT producers are probably at 10 percent utilization rates or below with all the new capacity they have. There’s just not enough industry using the material to constitute a beckoning.

I mean, the growth market for MWNTs appears to be in wind turbine blades and heads. That’s got to tell you something about the market’s prospects.

No, it’s not 2001 anymore, and little promotional pieces like this one kind of miss the mark a decade later.

The EC Defines a Nanomaterial: Now What?

This year I have been covering the sometimes-laughable efforts by the European Commission to define what a nanomaterial is so the Commission can develop a regulatory framework.

My views of this effort have evolved over time, and I see myself now firmly in the camp that believes arriving at a definition of nanomaterials when the science around the toxicity of nanomaterials is still so uncertain seems a counterproductive effort.

The counterargument that basically goes like this: How would one create a regulatory framework without a definition of some kind?

I suppose the simple answer to that would be to create a regulatory framework that was flexible and could be adjusted to the most recent and reliable science on the toxicity of nanomaterials. That seems a lot more sensible if one is indeed concerned about the potential threats of nanomaterials to the environment, health, and safety rather than quibbling over “how much” versus “how many” nanoparticles constitute a nanomaterial.

From what I could tell after speaking to some of the officials involved in this process, it seemed that arriving at a definition for nanomaterials was as much about public relations as about creating good regulatory policy.

That’s fine, of course, but after the EC announced its finalized definition for nanomaterials this week, it didn’t take long for the public, in the form of the European Environmental Bureau (EEB), to both express disappointment with the definition and to mock the amount of time it took to develop. So much for good public relations.

The definition itself…well, I don’t see how it helps to narrow anything, which I understand to be one of the main purposes of definitions. It would seem that the nanoparticles that are given off when your car’s tires roll along the pavement are now up for regulatory policy (“Nanomaterial” means a natural, incidental or manufactured material containing particles…”). And due to the lack of distinction between “hard” and “soft” nanoparticles in the definition, Andrew Maynard points out, “someone needs to check the micelle size distribution in homogenized milk.”

So what is the fallout from this definition? It would seem to be somewhat less than had been anticipated earlier in the year, when worries surrounded getting the definition just right because it would immediately dictate policy.

Instead, we are told that:

“Nanomaterials are not intrinsically hazardous per se but there may be a need to take into account specific considerations in their risk assessment. Therefore one purpose of the definition is to provide clear and unambiguous criteria to identify materials for which such considerations apply. It is only the results of the risk assessment that will determine whether the nanomaterial is hazardous and whether or not further action is justified.”

So basically they have created a class of materials that at the moment are not known to be intrinsically hazardous; but if some day they are, there is now a separate class for them. While some may see as this as making some sense, the sense of it eludes me.

Another Material Mimics Graphene's Capabilities

While listening to one of the better explanations I’ve heard of where we are with graphene’s capabilities in electronics applications, from Professor Ravi Silva, director of the Advanced Technology Institute at Surrey University, I saw that graphene was getting another competitor in the race for “wonder material” honors. 

You may recall from the beginning of this year how molybdenite was demonstrated to have a number of the same advantages graphene has over silicon in electronics but also has an inherent band gap.

In the joint research carried out in the labs of Helmholtz-Zentrum Dresden-Rossendorf (HZDR) linked to above, Dr. Frederik Wolff-Fabris and Dr. Jun Sung Kim came from South Korea discovered that when the metal SrMnBi2 (a mixture of strontium, manganese, and bismuth) is exposed to strong magnetic fields it behaves a lot like graphene.

In the coverage I have seen thus far for the research, which was published in the American Physical Society’s journal Physical Review Letters, I haven’t seen what characteristics the SrMnBi2 mimics of graphene, but I imagine it has to do with electron mobility.

It seems the real focus of the research was to observe various metals under a high magnetic field rather than seeking a new graphene. But because SrMnBi2 can easily be doped with foreign atoms, the researchers believe that this may allow for creating new magnets or superconductors for the material. 

It will be interesting to see if anyone pursues the graphene angle, in which case instead of the “carbon nanotechnology revolution” maybe we’ll be talking about the “SrMnBi2 nanotechnology revolution.”

A Pinch of Salt Makes All the Difference in Nanoscale Process for Hard Disks

Researchers in Singapore have developed a nanopatterning technique that enables hard disk drives to store potentially up to 3.3 Terabit/in2 of information, which is six times the recording density of current devices. 

In collaborative research between Singapore’s Institute of Materials Research and Engineering (IMRE), the National University of Singapore (NUS) and the Data Storage Institute (DSI), the researchers have been able to demonstrate data-storage capability of 1.9 Terabit/in2 and fabricated bits capable of up to 3.3 Terabit/in2 densities.

“What we have shown is that bits can be patterned more densely together by reducing the number of processing steps,” said Dr Joel Yang, the IMRE scientist who heads the project.

The process that the researchers came up with, published in the Institute of Physics journal Nanotechnology, involved the use of a high-resolution electron-beam lithography followed directly by magnetic film deposition. This essentially enabled the researchers to avoid the pattern transfer processes, such as etching and liftoff that manage to lessen pattern fidelity.

But the trick was in Yang’s discovery that by adding sodium chloride to the developed solution used in the lithography, “he was able to produce highly defined nanostructures down to 4.5 nm half pitch, without the need for expensive equipment upgrades.” 

Yang happened on this idea not during this research project but back when he was a graduate student at the Massachusetts Institute of Technology—and published it back in 2005

Nanomagnets Provide Protection from Lethal Counterfeit Drugs

A company that started off with the name SingularID over half a decade ago has long impressed me with its ability to take a nanomaterial—in this case nanomagnets—and develop a suite of tools around its physical phenomena to sell a product that helps in brand protection.

Bilcare Research acquired the small start-up back in 2007, and it seems the anti-counterfeiting technology could have a real impact in combating drug counterfeits in India, according to this recent BBC story

According to the BBC piece, counterfeit drugs are a $200 billion business whose main target continues to be poor and developing countries. What we’re talking about here is not just lost profits for the genuine drug producers, but also sometimes lethal consequences for people who need a particular drug but receive a fake one that lacks the active ingredient needed—or simply poisonous drugs.

The article goes on to explain that a number of technologies, including Bilcare’s, are under consideration for combating the counterfeit drugs. What I always found intriguing about the nanomagnet solution developed by SingularID and now marketed by Bilcare is that even they can’t make a copy of it—the nanoparticles position themselves in random patterns.

But beyond that, what always attracted me to the story of this technology is that the developers didn’t just settle with a nanomaterial and a patent and expect the world to come knocking on their door with lucrative licensing agreements. Instead, they developed an entire product that they could sell to someone. This has been surprisingly rare in the brief time that there have been nanotech companies.

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Nanoclast

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

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