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Nanotechnology Pushing Solar Power beyond the Shockley-Queisser Limit

Let’s face it. Solar power at this point seems to attract users from those who are affluent enough to have their social conscience trump their pocketbook.

In this excellent first-hand account here on the pages of Spectrum one engineer grappled with the decision to go solar, and the question for a long time for him was, “I figured solar would at most save me about $1000 per year in electricity, so how could I justify installing a $40 000 system?” Indeed.

As I’ve noted previously here the technology for photovoltaics has to bring us to a third generation solar cell that is both cheap to produce and highly efficient for it to start making financial sense. And when I am talking about efficiency I mean exceeding the 32% Shockley-Queisser Limit.

As I’ve noted the nanomaterials that seems to promise the best hope for achieving this breakthrough are quantum dots. Quantum dots look to be able to do this through either electron multiplication or creating so-called “hot carrier” cells.

Electron multiplication involves making multiple electron-hole pairs for each incoming photon while with hot carrier cells the extra energy supplied by a photon that is usually lost as heat is exploited to make in higher-energy electrons which in turn leads to a higher voltage.

In July this year, researchers at the University of Minnesota and Texas were able to achieve this capturing of heat energy for solar cells using quantum dots.

Now researchers at the University of Wyoming are pursuing a variation on electron multiplication by harnessing highly energetic photons (possessing more than twice the energy needed to free an electron) to free two electrons rather than one and thereby doubling the current generated.

The nanomaterial used once again was quantum dots. In this case the researchers coated a titanium dioxide electrode with a single layer of quantum dots. When the researchers shined light from the blue end of the spectrum on the material, they collected twice as many electrons as the number of absorbed photons. Leading them to conclude that each photon was generating two electrons.

Still the efficiency is not very high, and the researchers expect that if they can get to a 12 to 15% efficient solar cell that is produced at the cost of newsprint, they have something with commercial potential.

I still think that we should be looking at exceeding the Shockley-Queisser Limit and be able to do it with extremely cheap production techniques and then maybe we can break the stranglehold fossil fuels have on our energy solutions.

Better Mobile Phone Batteries, Please

I have expressed my dismay in the past with the odd fascination that Nokia and Cambridge University have with flexible mobile phones, and in particular their much publicized Morph phone concept.

This past week a number of news outlets have picked up on the annual update we get on the progress of this research. I particularly like this one because of the number of video interviews provided.

There is one video in particular that caught my eye and that is the one on a flexible supercapacitor. See below.

What took me a bit by surprise was the speaker, Piers Andrew, highlighting the idea that this supercapacitor would be excellent for enabling much more powerful flashes in flash photography. I certainly understand that supercapacitors are ideal for short bursts of energy like a camera flash, and that the field of making flexible supercapacitors is a fairly new one, so the pride of the Cambridge researchers is no doubt deserved.

But again I ask, is there anyone at the research team who uses a mobile phone? The issue that makes me want to throw mine against the wall is that the battery seems to have the life span of a nanosecond. I don’t want my phone to wrap around my wrist or take better flash photography at night from greater distances, I want mine to have enough power to go a month without having to recharge. Will anyone listen?

Nanotech Does Have an Impact on Formula 1

A few weeks back I commented on a conference that at the time was soon to take place and would address the topic of how nanotechnology could be, or is, applied to Formula 1.

I wondered what were the applications for nanotech in the highly regulated world of Formula 1 racing and whether a conference that had topics on its agenda like “Low Carbon Vehicle Initiative and Funding Opportunities” would really be able to address my curiosity.

We now have a first-hand account of the conference and a little insight into the applications of nanotech in Formula 1 that apparently weren’t addressed within the conference.

As to the accounting of the conference, no real surprises. It was put together by a UK-based metrology group and focused primarily on…metrology.

However, TNTLog in following up on the issue of applications in Formula 1 came across an interesting application that the conference organizers neglected. It seems that last year McLaren used the rather high-profile A123 battery technology on its cars.

TNTLog notes: “As far as I know, nanotechnology was used in the 2009 season, with McLarens KERS system using A123s nano phosphate lithium ion batteries as a result of their combination of weight and charge/discharge capacity.”

It would also seem that the more strict and specific Formula 1 attempts to makes its rules on the use of nanomaterials, the more ripe it is for loopholes. When one considers the money difference a sponsor is willing to pay for a pole-position car and that of one on the back row, we are likely to see more and more ingenious uses of nanotech.

IBM's Breakthrough in STM Imaging Promises Big Changes in Nanotechnology Research

Nanotech news is buzzing this week with the announcement that researchers at IBM’s Almaden Research Center have significantly advanced the speed at which a Scanning Tunneling Microscope (STM) can image an atom.

It is now possible to take images of an atom at nanosecond speeds as opposed to mere millisecond speeds. To give you a sense of how big a difference in time this is, think of a millisecond as equivalent to 30 years while a nanosecond would be just one second.

The researchers, who initially published their work in the September 24th edition of Science, were able to achieve this enormous increase in speed by employing a “pump probe” measurement technique, in which the time difference between a fast voltage pulse exciting the atom and then a weaker voltage pulse measuring the magnetism of the atom after the excitation creates a time frame for each measurement. The STM taking images at the rate of 100 million frames per second creates a sort of moving picture of the magnetic motion of the atom.

Some see this as a step towards bringing Moore’s law to its inevitable conclusion, i.e. storing information on an individual atom. And, indeed, the researchers’ demonstration of their imaging technique indicated that various manipulations of an atom can dramatically change their ability to store information.

Previously it had been determined that an iron atom could hold data for only a nanosecond. With this technique, the researchers were able to manipulate the iron atom by placing it near non-magnetic copper atoms and found the iron atom could then hold the data for 200 nanoseconds. If they didn’t have this technique they may not have been able to properly observe that phenomenon.

I have to give credit to the IBM researchers for putting this into some perspective. This is a significant advancement in conducting nanoscale research but nobody should be expecting commercial products anytime soon and the IBM researchers try to nip that idea in the bud in published reports.

According to Andreas Heinrich, IBM Research staff member and group leader of nanoscale science at the Almaden Lab, who was interviewed for the eWeek article cited above, “it is far too early to tell if or how this will result in productized technologies. It will probably take another two to five years to determine whether atoms can be manipulated to store data for hours or days, rather than nanoseconds, and even longer—15 years or more—to determine whether any of this research will result in products.”

While this is certainly the circumspect approach to news of this breakthrough, one can understand the enthusiastic reactions to its announcement from some peers. In the same eWeek article, Michael Crommie, professor of physics at the University of California Berkeley and a faculty researcher at the Lawrence Berkeley National Labs, said in a statement. "I am particularly excited by the possibility of generalizing it to other systems, such as photovoltaics, where a combination of high spatial and time resolution will help us to better understand various nanoscale processes important for solar energy, including light absorption and separation of charge."

Now if someone can come up with a microscopy tool that excites the biologists as much as the physicists, then we might have universal joy among nanotechnology researchers.

Piezoelectric Nanowires Enable Energy Generation through Sound

Over at Nanowerk they have spotlighted research coming out Korea that has demonstrated the ability to use piezoelectric nanowires that can turn 100 decibel into enough energy to power very small electronic devices “self-powered sensors, e-papers, or body-implantable tiny devices” with the aim of powering larger devices when new nanomaterials are developed.

According to Dr. Jong Min Kim, Director of Frontier Research Lab, Samsung Advanced Institute of Technology (SAIT) and Sang-Woo Kim, a professor in the School of Advanced Materials Science & Engineering at Sungkyunkwan University, it is very difficult to use mechanical energy from sound in order to generate electrical energy using a conventional PZT-based bulk or thin film piezoelectric energy harvester.

The researchers overcame this obstacle by employing zinc oxide nanowires to serve as piezoelectric material sensitive enough to respond to sound energy. The nanogenerator device they made was able to transform 100 dB into an AC output voltage of 50mV.

The research was originally published in August 30, 2010, online issue of Advanced Materials.

The clearest application for this technology would be in cellular phones where one’s conversations could be used to power the device. However, since our speaking voice is around 60-70 dB and the device currently is not effective in generating power from sound less than 100 dB, it’s clear that more work has to be done.

The researchers believe the biggest obstacle they need to overcome is the limitations of zinc oxide, which they believe will help them design a device that will have improved piezoelectric performance.

Protein-based Nanotubes Pass Electrical Signals Between Cells

A few years back, scientists led by Hans-Hermann Gerdes at the University of Bergen noticed that there were nanoscale tubes connecting cells sometimes over significant distances. This discovery launched a field known somewhat by the term in the biological community as the “nanotube field.”

Microbiologists remained somewhat skeptical on what this phenomenon was and weren’t entirely pleased with some explanations offered because they seemed to fall outside “existing biological concepts.”

However, now Gerdes and his team have offered up an explanation that seems to be pleasing the skeptics.

In a recent paper published in Proceedings of the National Academy of Sciences the Norway-based researchers have shown that electrical signals can be passed through the nanotubes and that “gap junctions” are involved in the transmission process.

It is this gap junction bit that seems to be satisfying the skeptics. Gap junctions are proteins that create pores between two adjacent cells and create a direct link between the cells. But the key word in the definition is “adjacent” with these “tunneling nanotubes” or “membrane nanotubes” as they are alternately called, cells can communicate without being adjacent.

"The authors of this paper have identified an exciting way that cells can communicate at a distance. That means you can no longer just think of cells touching each other to coordinate movement," says Michael Levin of Tufts University in Medford, Massachusetts in the Nature article cited above. "Understanding what physiological information these nanotubes pass on will now be a key question for the future."

Among other biological systems that this may help us to better understand is the development of an embryo in which there is massive coordinated cell migration to form the various organs of the body.

Another key biological question it helps address--or complicate, as the case may be--is the complexity of the human brain. This research makes the brain drastically more complex than originally thought, according to Gerdes.

This could tangentially complicate Ray Kurzweil’s Singularity concepts at least in so far as duplicating the human brain, if current skepticism wasn't damaging enough.

Nanotechnology as a Tool for Economic Recovery

After the near-total collapse of the US economy two years ago, the economy has recovered to the point at least that it has crawled its way out of recession, albeit with little being done for unemployment. Now we get a pretty regular stream of advice on how the US can improve this situation and avoid a second recession and perhaps a deflationary spiral.

Along those lines, I came upon this recent article over at MarketWatch that urges a huge government investment in 21st Century technologies, including nanotechnology, that will fundamentally restructure the US economy and will reindustrialize, if you will, the US economy.

I do get the argument and I am a sympathetic with much of it. We do need to look to new technologies, including nantechnology, for creating new sources of wealth in the US economy.

However, I think the real problem is that governments have so conditioned businesses, industry and the investment community to expect government to do all the heavy lifting in the funding of research, they have neglected even their own interests in actual wealth generating activities and have preferred to sit back and enjoy the high yields from derivatives or profits from products that they had little hand in actually developing.

At some point in the innovation processes, private capital instead of public funding has to pick up the torch and bring technologies to market. Sadly, we have seen less and less of that recently and in the last two years practically none at all despite banks and other similar institutions experiencing enormous growth in their wealth.

As a result, we have seen a real lag in the government strategy types realizing that industry is not government’s partner anymore but instead just their fatted-up dependant, greedily waiting for their next gift. This lack of recognition means that government strategists still think they can pick technologies off a tree and apply them to the world’s problems. They can’t. It won’t work.

As things currently stand, we will continue to see new advancements in nanotechnology for attractive applications like solar energy, which seem to promise real commercial success, languish in the in-between world of a government grant and commercial products. The answer is not for the government to apply more funding but for there to be some new structure to the innovation process in which private industry and financing takes on some of the risk of bringing a new technology to market.

It’s time for some arm-twisting and a reading of the riot act to the overly dependent and apathetic private investors that makes it clear that the current state of affairs is not sustainable, and not even in their long-term interests. But getting the investment community to look beyond a three-month horizon, never mind a seven to ten year one, has become nearly impossible. Fixing that may be the real restructuring that the US economy needs.

Nanowire Thin Film Transistors Impart the Sense of Touch for Artificial Limbs

Imparting the sense of touch to artificial skin for both robotics or for prosthetics of amputees has proven difficult.

However two new solutions have been reported for making an artificial skin that possesses an extremely sensitive sense touch. One comes out of the University of California Berkeley and the other comes ironically from neighbor and rival Stanford University, both of which were reported in the journal Nature Materials.

IEEE Spectrum has a good article this week on the technology and how it is likely to be developed in the short term.

In keeping with the rivalry we get a good run down of the pros and cons of each technology in the BBC article cited above. The Stanford research, led by Zhenan Bao, produces the same pressure sensing as the Berkeley research but with fewer layers by making its nanowire-enabled thin-film transistors (TFTs) pressure sensitive rather than laying the nanowire TFT array onto a pressure-sensitive array.

Despite this advantage, the Berkeley solution has greater flexibility, leading Bao to concede in the article that her group’s approach will need to develop a better conductive rubber.

Both solutions have demonstrated remarkable sensitivity. The artificial skins react to a stimulus in a tenth of a second and in weights ranging five grams per centimeter to 40 times that amount, according to the BBC article. According to the video below, the Stanford development could sense the touch of a butterfly or a drop of water. 

As impressive as this is, perhaps the greatest part for both these lines of research are that they were able to accomplish their results by using fairly inexpensive manufacturing techniques.

In a critique for Nature Materials John Boland, a nanotechnologist from Trinity College Dublin, commented, "Perhaps the most remarkable aspect of these studies is how they elegantly demonstrate that it is possible to exploit well-established processing technologies to engineer low-cost innovative solutions to important technical problems."

Carbon Nanotubes Serve as Funnel for Photons on Solar Panels

Nothing excites the imagination of the general public or researchers in the area of alternative energy like solar power does. You can explain until you’re blue in the face how wind power is cheaper per Kwh than solar, or how nanotech is really having an impact now on saving energy as opposed to generating it.

But it all hardly seems to matter. People want to know how nanotech is going to enable solar power. The latest news item comes out of MIT where researchers have formed carbon nanotubes into a kind of antenna that focuses photons onto photovoltaic cells and reportedly concentrates solar energy 100 times more than a regular cell.

According to Michael Strano, the leader of the research team and Charles and Hilda Roddey Associate Professor of Chemical Engineering at MIT, this development could result in smaller solar arrays.

“Instead of having your whole roof be a photovoltaic cell, you could have little spots that were tiny photovoltaic cells, with antennas that would drive photons into them,” says Michael Strano in the article.

The work was originally published in the Sept. 12 online edition of the journal Nature Materials.

The antennas are made of about 30 billion carbon nanotubes and resemble a fibrous strand with dimensions of 10 micrometers long and four micrometers thick. The fiber has different bandgaps. The inner layer of the fiber has a small bandgap while the outerlayer have a higher bandbap. So when photons hit the antenna all the excitons flow to the center of the fiber thereby concentrating them.

While this is all very far off from even a full-fledged prototype since the researchers have not yet built a photovoltaic cell that could use the antenna, it seems that commercial considerations are already being taken into account with concerns about the price per pound of single-walled carbon nanotubes being discussed.

One would think that a discussion of economic issues like price of raw materials and phrases like “100 times” better than existing technologies would interest funding types. But likely they see 10 years before a ROI and myriad competing technologies and shrug.

Stock Investment Advice for Nanotechnology Seems Cruel

Every now and then there’s a new nanotech investment story that gets circulated around, and the latest comes from a publication called the Street Authority.

It starts out on target by pointing out that 10 years ago after the Internet bubble burst investors were clamoring for a new investment vehicle when along came nanotechnology. This is a point I made myself three years ago, so I am open to accepting this line of thinking.

But the article goes all a bit fuzzy after that with an odd collection of “nanotech” stocks that reminds one of the rather odd practice of creating nanotechnology stock indices. Unfortunately many of the indices I cited three years ago are long since gone, so no more giggles, I’m afraid.

Anyway in this latest abbreviated index we see FEI Company paired up with Altair Nanotech. Really? Now I am well aware that FEI likes to market itself on occasion as the “Nanotech Company”, but the huge microscopy company has remained largely in the semiconductor business.

But even if you didn’t know that, you could just look at the table the reporter has provided and see something is amiss. While FEI currently has a market cap of $668 million, it had revenues of $577 million last year and probably has loads of cash. And in the same table, we get Altair with a market cap of $63 million and 2009 sales of $4.4 million.

Now I am no investment expert like the reporter, but it would seem the Price to Sales ratio is more than a little different between these two companies. My point is that they can’t really both represent speculative stock investments.

But the entire enterprise of providing stock investment advice on so-called nanotech companies is just cruel to small time investors and misses the real reason of why nanotechnology has not been further commercialized than it is.

The real obstacle keeping nanotechnology from having greater success is not because of a lack of mom-and-pop investors in the handful of nanotech penny stocks. Rather the problem preventing nanotechnology from being further commercialized is that private equity (i.e. angel investors, venture capitalists, sovereign funds and banks) just is not investing money outside of high-gain investments like derivatives and the like. And I think we all know where that landed the world economy, never mind nanotechnology.

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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
 
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Rachel Courtland
Associate Editor, IEEE Spectrum
New York, NY
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