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Spray-On Technique Could Bring Carbon Nanotubes to Retailers’ Shelves

Carbon nanotubes appear to be getting back some of their glory—after seemingly being eclipsed by graphene—with the news yesterday that an entire computer could be made from the material.  Now researchers at Technische Universität München (TUM) in Germany are continuing the carbon nanotube comeback with a new, inexpensive process that promises to enable their use in a wide range of applications including electronic skin and sensors integrated into food packaging.

The process, which involves simply spraying the carbon nanotubes onto a flexible, plastic substrate, is described in the journal Carbon (“Fabrication of carbon nanotube thin films on flexible substrates by spray deposition and transfer printing”)

"To us it was important to develop an easily scalable technology platform for manufacturing large-area printed and flexible electronics based on organic semiconductors and nanomaterials," said postdoctoral researcher Alaa Abdellah in a press release. "To that end, spray deposition forms the core of our processing technology."

In the food packaging application, the carbon nanotubes would serve as gas sensors. Nanotubes have long proven themselves to be good sensors. They can be made to bind to certain substances, which changes the electrical properties of the nanotubes in a way that can be measured with a high degree of sensitivity.

In practical applications, the carbon-nanotube-enabled plastic would cover a grocery store product like chicken. If the product contained the chemical indicators of, say, salmonella, the packaging would detect them and alert the consumer.

While this sounds great, the obstacle preventing this from becoming a reality has always been cost. Thin-film sensory packaging may make sense for a high-cost item, but for an inexpensive grocery store product, it’s hard to justify an additional cost that may be as much as the product itself. I made this point nearly a decade ago in report I authored titled, "The Future of Nanotechnology in Printing and Packaging".

This doesn’t even take into account the often biased opinion people have about nanotechnology in relation to food.

For these reasons, I recommend that the researchers focus their attention on high-ticket applications such as electronic skin for robotics and bionics. In those applications, they will likely find greater resistance to the fear mongering practiced by the NGOs. And it just might make more economic sense to adopt their technology for those applications.

Image: Uli Benz/TUM

Plastic OLEDs Just Got a Bump from Silver Nanowires

Polymer-based OLEDs (organic light-emitting devices) have been held out as a kind of Holy Grail in lighting and display applications. Part of their unachievable-quest notoriety stems from the fact that they are expensive in part due to the complex processing involved. Nonetheless, they do possess the magical feature of being flexible.

Researchers at the University of California Los Angeles (UCLA) have developed just such an OLED material that can be twisted and folded and even stretched while remaining lit the entire time and could become the template for all future polymer OLEDs.

"Our new material is the building block for fully stretchable electronics for consumer devices," said Qibing Pei, a UCLA professor of materials science and engineering and principal investigator on the research, in a press release. "Along with the development of stretchable thin-film transistors, we believe that fully stretchable interactive OLED displays that are as thin as wallpaper will be achieved in the near future. And this will give creative electronics designers new dimensions to exploit."

The material, which was described in the journal Nature Photonics ("Elastomeric polymer light-emitting devices and displays"),  owes at least part of its remarkable stretching capabilities to new transparent electrodes the researcher made out of silver nanowires that have been inlaid into the polymer.

Silver nanowires are currently being market by companies like Cambrios Technologies and Blue Nano for use as a replacement to indium tin oxide (ITO) as a transparent conductor to control display pixels.

In this latest application, the UCLA researchers found that when a single layer of an electro-luminescent polymer blend is sandwiched between the silver nanowire electrodes it was possible for the OLED to bend and stretch at room temperature.

As you can see from the video below, the researchers are able to bend and stretch the OLED into every conceivable shape and do it while in normal ambient conditions.

"The lack of suitable elastic transparent electrodes is one of the major obstacles to the fabrication of stretchable display," said Jiajie Liang, a postdoctoral scholar, in a press release. "Our new transparent, elastic composite electrode has high visual transparency, good surface electrical conductivity, high stretchability and high surface smoothness — all features essential to the fabrication of the stretchable OLED."

While the video demonstrates an OLED with just a solid block of light, the researchers have shown that they can create an OLED made up of different pixels, which opens up the possibility of stretch displays as well as new kinds of lighting.

The researchers were able to accomplish this pixel capability by arranging the silver nanowire-based electrodes into a cross-hatched pattern made up of one layer of columns and one layer of rows.

"While we perceive a bright future where information and lighting are provided in various thin, stretchable or conformable form factors, or are invisible when not needed, there are still major technical challenges," Pei conceded in the press release "This includes how to seal these materials that are otherwise sensitive to air. Researchers around the world are racing the clock tackling the obstacles. We are confident that we will get there and introduce a number of cool products along the way."

Graphene Investment Advice Needed, Just Not the Stock Market Variety

With research developments coming daily—if not hourly—in graphene, it really was just a matter of time before investment gurus were going to start giving stock tips. This is not altogether bad. It keeps everything focused on the purpose of pursuing graphene developments to create new and improved products that will enable somebody to make some money.

Unfortunately, the field of nanotechnology has a somewhat checkered past with the stock market and with investment gurus. We’ve been subjected to nanotechnology stock indices that thankfully have (for the most part) withered away. And we’ve seen so-called stock market experts proclaim that a huge company with enormous revenues and cash reserves is the same kind of speculative stock investment as a small start-up. It would seem these “experts” not only don’t know nanotechnology, but also don’t understand simple stock analysis metrics like price-to-earnings ratios.

Now it’s graphene’s turn. There has been a recent flurry of investment reports on graphene, motivating some bloggers to comment on the trend. I was finally nudged into a offering my observations now because of a piece that appeared this week in Forbes (“Graphene Stock Investing: What The Pros Think”) . As these articles go, this is a top-notch effort. But I have to quibble about one point—and it’s a big one—graphene at the moment is not a stock market play.

Here is a list of 39 graphene companies, and I don’t believe that there’s one of them on that list that is at this moment publicly traded. So, after the author asks two investment experts what stocks they would suggest for exploiting all the activity in graphene, we get as a response: Enersys, Tesla Motors, and Johnson Controls without giving any explanation of why these companies constitute  good graphene investments. It’s not even clear how they are involved in graphene.

I suppose in the case of Enersys and Tesla it’s a belief that graphene could enable improved batteries for all-electric vehicles. While I have no idea whether these companies are good stock investments or not, I am pretty certain that their fortunes good or bad are not tied to the fate of graphene one way or the other, especially for a hugely diversified company like Johnson Controls.

I support and would even champion articles that could raise awareness of how crucial it is to invest in companies that are trying to develop products based on graphene. We actually need more of them. Unfortunately, we rarely get those kinds of articles and instead get articles like the one in Forbes that are aimed at those interested to know how they can spend their savings on a “graphene stock market investment,” when, in fact, there is no such thing.

While this is unfortunate, it indicates a perhaps more troubling issue. The kind of early, pre-IPO investment that a company trying to develop products based on graphene needs has become increasingly difficult to source outside of governments as large private capital sources still prefer the fast investment turnarounds offered in complex financial instruments. It’s even got graphene’s co-discoverer, Andre Geim, lamenting society’s current attitude of “throw[ing] a little bit of money at something and expect[ing] it to change the world.

By most estimates products enabled by graphene should really start hitting the market in 2020. With that investment horizon, why are we even talking about the stock market when we should really be discussing how we can support innovation at these early stages. Do that and someday we can actually have publicly traded companies that make products based on graphene.

Image: Erik Vrielink

Graphene Leading the Way to Optical Chips

In a joint research project, researchers from the Massachusetts Institute of Technology (MIT), Columbia University, and IBM’s T. J. Watson Research Center have used graphene as a photodetector for enabling an optical chip.

Graphene has tantalized researchers in photodetector applications with its wide spectral range (from the ultraviolet to the infrared), fast optoelectronic response that is the result of high electron mobility, and its lack of a band gap. However, graphene can absorb only a small fraction of incoming light, so its responsivity has been limited.

While this minimal light sensitivity may limit its use in digital camera applications, the MIT, Columbia, and IBM researchers may have engineered a way to use graphene as a photodetector for converting light into electricity for integrated optoelectronic chips.

The research team, which published its work in the journal Nature Photonics (“Chip-integrated ultrafast graphene photodetector with high responsivity”)  developed a method by which they could overcome graphene’s low responsivity to incoming light (measured at between 2 and 3 percent of the light passing through it being converted to electrical current). They turned to creating a bias in the photodetector so that electrons that were disrupted by incoming photons would remain in a higher energy state.

Typically, creating this bias involves maintaining voltage through the photodetector. However, this voltage is a source of noise that compromises the photodetector’s readings. To avoid this noise, the researchers turned to the work of Fengnian Xia and his colleagues at IBM; they produced a bias in a photodetector without the application of a voltage.

This trick is accomplished through an ingenious design in which light is funneled into the photodetector through a channel—or a waveguide—that is capped with a piece of graphene oriented perpendicular to the channel. The graphene has gold electrodes on either side of it, but instead of them being evenly spaced, one of the electrodes is closer to the graphene than the other.

“There’s a mismatch between the energy of electrons in the metal contact and in graphene,” said Dirk Englund, an assistant professor at MIT and the leader of the research team, in a press release. “And this creates an electric field near the electrode.”

So in operation, photons come through the channel and start kicking the electrons up to a higher energy state. These excited electrons are then pulled to the electrodes by the electric field, thereby creating a current—without applying a voltage.

This voltage-free bias boosts the photodetector to the point where it could generate 100 milliamps per watt, a responsivity equal to that of germanium. The researchers believe that with a bit of engineering (i.e., thinner electrodes, and a narrower waveguide), it could be possible to boost these results by a factor of two or perhaps even four.

The impact of chips that use light rather than electricity is clear. They will consume less power and produce less heat. Both of these factors have become ever more critical as chip features get smaller and smaller.

Thomas Mueller, an assistant professor at the Vienna University of Technology’s Photonics Institute, and a co-author of very similar research in the same journal, noted in the press release: “The other thing that I like very much is the integration with a silicon chip, which really shows that, in the end, you’ll be able to integrate graphene into computer chips to realize optical links and things like that.”

Image: MIT/Columbia University/IBM

Top-Down and Bottom-Up Manufacturing Combined in One Technique

An international team of researchers has combined ink-jet printing and self-assembling block copolymers to create a hybrid between top-down and bottom-up manufacturing. This new hybrid approach to building nanostructures promises to overcome the obstacles of fabricating nanostructures out of polymers and other soft materials.

The research, which was published in the journal Nature Nanotechnology ("Hierarchical patterns of three-dimensional block-copolymer films formed by electrohydrodynamic jet printing and self-assembly"),  found that by using self-assembling block copolymers  in combination with ink-jet printing that the resolution for even the best ink jet printers  could be improved from approximately 200 nanometers down to about 15 nm.

Block copolymers are chain like molecules made up of blocks of two types of chemicals. (Imagine a string of Christmas lights having a repeating pattern of 5 green lights and 5 red lights.) Under the right circumstances, such copolymers can fold up to form patterns such as a repeating array of holes.

The ITRS roadmap has long identified block copolymers for use in reducing chip feature sizes. For years block copolymers have demonstrated their usefulness in creating self-assembled photoresists for chip manufacturing.

While the potential for self-assembling block copolymers have long been understood, this work—which is a cooperative effort of researchers from University of Illinois at Urbana-Champaign, the University of Chicago, and Hanyang University in Korea—adds an important twist.

“The most interesting aspect of this work is the ability to combine ‘top-down’ techniques of jet printing with ‘bottom-up’ processes of self-assembly, in a way that opens up new capabilities in lithography—applicable to soft and hard materials alike,” said John Rogers, a materials science professor at Illinois and one of the authors of the paper, in a press release.

In the work described, the international team turned to the Belgium-based nanoelectronics powerhouse Imec to create chemical patterns over large areas of a substrate with high precision. The research team in Illinois then used ink jet printing to deposit block copolymers on top of these patterns. The block copolymers would self-organize following the patterns laid on the underlying template. The result was that it created patterns that had a greater resolution than the template itself.

While previous work had managed to deposit films on these templates, the result was that the patterns only possessed one characteristic feature size and spacing. With the ultra-precise ink-jet printing tool, it became possible to create multiple dimensions in one layer.

“This invention, to use inkjet printing to deposit different block copolymer films with high spatial resolution over the substrate, is highly enabling in terms of device design and manufacturing in that you can realize different dimension structures all in one layer,” said Paul Nealey, a professor at the University of Chicago and co-author of the paper, in the press release. “Moreover, the different dimension patterns may actually be directed to assemble with either the same or different templates in different regions.”

Image: Serdar Onses/University of Illinois-Urbana

"Piranha Etching" Could Push Nanowire Solar Cells Way Past Theoretical Limits

Researchers at the Eindhoven University of Technology, Delft University of Technology and the company Philips in the Netherlands have developed a method for increasing the conversion efficiency of nanowire-based photovoltaic cells: Give them a good cleaning.  While the researchers have demonstrated an increase to 11.1 percent efficiency with their technique, it is the long-term prospects of the method that appear the most promising with estimates for the conversion efficiency ultimately reaching 65 percent.

The potential for nanowire-based photovoltaics to reach extremely high conversion efficiencies was demonstrated earlier this year when researchers at the Nano-Science Center at the Niels Bohr Institut in Denmark and the Ecole Polytechnique Fédérale de Lausanne in Switzerland suggested that nanowire photovoltaic cells could surpass the Shockley-Queisser limit. The Shockley-Queisser limit is a theory established in 1960 that suggested among other things that that only 33.7 percent of all the sun’s energy could be converted into electricity for solar cells with a single p-n junction. To surpass this limit has been a  Holy Grail quest of sorts for photovoltaics.

Now with this latest research  the Shockley-Queisser limit could be surpassed by a huge margin. The technique, which is described in the journal Nano Letters (“Efficiency Enhancement of InP Nanowire Solar Cells by Surface Cleaning”)  involves a surface cleaning of the nanowires.

The cleaning is a chemical reaction that the researchers have dubbed “piranha etching”. The result of the process is that indium phosphide nanowires come out much smoother and have fewer imperfections.

This cleaning of the surface addresses the Achilles Heel of nanowire photovoltaics. While the surface area of nanowires enables photovoltaics to be produced without using as much costly semiconductor material as ordinary photovoltaics do, the nanowires cell's large surface area is prone to have imperfections that result in energy loss.

The 11.1 percent conversion efficiency achieved by the Netherlands-based researchers does not equal the record of 13.8 percent achieved by an international team of researchers earlier this year. However, that may be of little consequence if the promise of this latest research can be realized.

“By varying the thickness of the nanowires and improving the way the crystals inside them are stacked, we think we should soon be able to approach an efficiency of 20 percent”, says Professor Erik Bakkers, one of the lead researchers, in a press release.

Following this basic approach, the researchers believe that theoretically they could reach a conversion efficiency as high as 65 percent. If that’s true, and it can be produced relatively inexpensively, it'll be a game changer.

Image: Eindhoven University of Technology

Article Makes a Hash out of Nanotechnology and its Impact

Over the years, I thought I had become accustomed to mainstream journalists making a hash out of the subject of nanotechnology. I've even had the misfortune of watching videos starring famed TV physicists making bizarre predictions about the problems that will ensue from the changes brought on by nanotechnology. I thought I had steeled myself so I would not be bothered by these sorts of things anymore, but along came the latest mishmash of half-informed scaremongering.

It’s a perfect storm of wrongheadedness. It was penned by Ainissa G. Ramirez, Ph.D., a noted author and “science evangelist,” giving it an air of veracity. But that doesn't keep the piece from going wrong right from the outset. You can find the first misstep in the second sentence: “By miniaturizing matter, science fact will look like science fiction.” Okay, once and for all: Nanotechnology has nothing to do with miniaturizing matter. Nanotechnology is not the real-life version of the 1960s sci-fi film “Fantastic Voyage.” We are not shrinking matter.

Ramirez apparently skimmed the wrong articles to mine that nugget of information. The rest of the article, as far as nanotechnology is concerned, scans about right; it includes all the typical references you would expect from someone who skimmed some articles on nanotechnology: gold is red at the nanoscale, using hair to visualize the nanoscale, et cetera.

This is not to say Ramirez does not fudge some other references to nanotechnology for dramatic effect. For example, there's this gem: “Do we want small particles—which we can't imagine let alone see—swimming in our water supply and covering everything around us?”

Swimming? Covering everything around us? Really? The "scholarly paper" she must have been referencing is Michael Crichton’s novel “Prey.” Outside the world of fiction, man-made nanoparticles are not going to cover everything.

While these egregious misstatements of fact got my blood boiling, it’s the main thesis of the article that is perhaps the biggest problem. Ramirez’s argument boils down to the idea that pursuing technology has unintended consequences that, in balance, are bad for us. This is a popular meme among so-called environmentalists. Ramirez suggests that the automobile, while likely considered a really great idea at the time of its invention, brought on obesity because it eliminated an alternate course of history wherein we would have been walking or cycling. I suppose this line of argument appeals to a certain segment of the population that would like us to return to the bucolic times before all the inventions of our modern age. Sigh. Why can’t these technology-for-dummies summaries ever be informed or reasonable?

To address the crossroads that Ramirez believes we are approaching with nanotechnology (where it could potentially be the next thing to blame for our obesity), she suggests public engagement and dialog about its impact. Really? What a novel idea. Too bad it seems to have escaped Dr. Ramirez’s skimming that there has been so much public engagement for years now that research has been looking at whether it has any usefulness. It also doesn’t help matters that the very people that will accept Ramirez's line of thinking are the ones who have boycotted public engagement efforts.

Worse yet, the article was published in the perfect vehicle for wide dissemination: the Huffington Post, which is as mainstream as it gets. So a lot of people are apt to read the article and be misinformed. The Huffington Post is developing a rather poor reputation for its coverage of nanotechnology. And it's a pity because there are lots of brilliant commentators on the subject of nanotechnology’s potential impact—people who could provide well-reasoned and substantiated arguments on the topic.  Ramirez's article, unfortunately, does neither.

Photo: David Monniaux/Wikipedia

Bismuth-filled Carbon Nanotubes Improve CT Scans

Research has shown in recent years that carbon nanotubes can improve fluorescence imaging, replacing the dyes that are typically used. Now researchers at Rice University have demonstrated that carbon nanotubes combined with bismuth can improve the capabilities of computed tomography (CT) scans.

The Rice team has filled single-walled carbon nanotubes with bismuth compounds to make for a more effective contrast agent than is currently available for CT scans.

The research, which was published in the journal of Materials Chemistry B (“Bismuth@US-tubes as a potential contrast agent for X-ray imaging applications”), builds on previous work that examined the use of bismuth as a contrast agent in CT scans and on the Rice team’s own research into using carbon nanotubes as a contrast agent in magnetic resonance imaging (MRI).

According to Rice chemist Lon Wilson, this is the first time that bismuth has been combined with nanotubes for use as a contrast agent for imaging individual cells.

“At some point, we realized no one has ever tracked stem cells, or any other cells that we can find, by CT,” Wilson said in a press release. “CT is much faster, cheaper and more convenient, and the instrumentation is much more widespread (than MRI). So we thought if we put bismuth inside the nanotubes and the nanotubes inside stem cells, we might be able to track them in vivo in real time.”

The new contrast agent starts off as single-walled carbon nanotubes that have been chemically processed to make them into capsules with dimensions of between 20 and 80 nanometers long and about 1.4 nanometers in diameter. These nanocapsules are then are mixed with bismuth chloride to form what the researchers have dubbed Bi@US-tubes.

Once the Bi@US-tubes are introduced in vivo, they are small enough to diffuse into individual cells where they aggregate into a clump approximately 300 nanometers in diameter. “We think the surfactant used to suspend them in biological media is stripped off when they pass through the cell membrane,” Wilson said in the press release. “The nanotubes are lipophilic, so when they find each other in the cell they stick together.”

“The cells adjust over time to the incorporation of these chunks of carbon and then they go about their business,” Wilson adds in the release.

Bismuth is more effective at diffracting X-rays than the iodine in today's contrast agents, or just about any other material. When it is put in the nanocapsules, the resulting combination can produce high contrasts in very low concentrations.

The surfaces of the nanotubes can also be modified in ways to make them target different kinds of cells and make them more biocompatible.

The next step in the research will be to increase the amount of bismuth in the capsules so as to improve their contrasting capability.

Image: Eladio Rivera/Rice University

Gold Nanoparticles Make Molybdenum Disulfide Extra Special

While graphene has been on a nearly decade long surge of research, its two-dimensional (2D) rival molybdenum sulfide (MoS2) has enjoyed an equal rush of interest over a mere two-and-a-half years. Ever since researchers at Ecole Polytechnique Federale de Lausanne’s (EPFL) Laboratory showed it could be used in replacing silicon in transistors in early 2011, the competitive landscape for 2D materials has gotten a little crowded. Despite the growing competition between 2D materials, MoS2 still holds a special place among the competition because it can be used to further enable graphene or work on its own in the next generation of nanocircuits.

Now researchers Kansas State University have raised the prospects of MoS2 a little bit higher by combining it with gold nanoparticles. The researchers believe that the incorporation of gold nanoparticles with MoS2 will open greater possibilities for the material in diverse applications such as transistors and biochemical sensors.

The research, which was published in the journal NanoLetters ("Controlled, Defect-Guided, Metal-Nanoparticle Incorporation onto MoS2 via Chemical and Microwave Routes: Electrical, Thermal, and Structural Properties"), focused on the surface structure of MoS2. The team decided that MoS2's strong chemical bond with noble metals, like gold, could be an avenue for investigation.

They were not disappointed. They quickly discovered that once a bond had been established between the MoS2 and gold nanostructures, the bond behaved like a highly coupled gate capacitor. Following on this discovery, the Kansas State team was able to further enhance the transistor characteristics of MoS2 by manipulating it with the gold nanostructures.

"The spontaneous, highly capacitive, lattice-driven and thermally-controlled interfacing of noble metals on metal-dichalcogenide layers can be employed to regulate their carrier concentration, pseudo-mobility, transport-barriers and phonon-transport for future devices," Vikas Berry, a professor at Kansas State and a leader of the research, said in a press release (though it does stretch the bounds of credulity to imagine him actually speaking these words aloud without pausing numerous times for breath).

Among the transistor characteristics of MoS2 that the researchers were able to manipulate with the gold was its power requirements. The team also demonstrated a direct route for attaching electrodes to a MoS2 tunneling gate.

"The research will pave the way for atomically fusing layered heterostructures to leverage their capacitive interactions for next-generation electronics and photonics," Berry said. "For example, the gold nanoparticles can help launch 2-D plasmons on ultrathin materials, enabling their interference for plasmonic-logic devices."

In further research, the team intends to create more complex nanoscale structures with MoS2, leading to the building of logic devices and structures.

With MoS2 having the advantage of an inherent band gap—unlike graphene—and the recent flood of research that’s turning up new ways to work with, it may have a slight advantage over graphene at the moment for transistor applications.

Image: Vikas Berry

Dye-based Solar Cells Get Bump in Conversion Efficiency and Lifespan

As I pointed out this week, inexpensive photovoltaics are good, but inexpensive and efficient ones are much better. For years now, the dye-sensitized solar cell (DSSC) has been one of the least expensive photovoltaic devices on the market. But even one of the inventors of the technology conceded just a couple of years ago that there needed to be a big push to improve the energy conversion efficiency of the devices.

While new manufacturing techniques have recently been proposed that should further reduce the manufacturing costs associated with producing DSSCs, a bit of a bump up in conversion efficiency would perhaps be a more welcome development.

To meet this need, researchers at the KTH Royal Institute of Technology in Sweden have developed a method for making DSSCs that are not only are more efficient but longer lasting. The foundation of the improvement is a new, quasi-liquid, polymer-based electrolyte that increases the solar cells' voltage and current and lowers resistance between electrodes.

DSSCs are essentially a photochemical system in which a photo-sensitized anode and an electrolyte form a semiconductor. In their commercial incarnation, today's DSSCs consist of a porous layer of titanium dioxde (TiO2) nanoparticles that have been covered with a molecular dye that absorbs sunlight, and a platinum-based catalyst. The TiO2 , which is immersed in an electrolyte solution that acts as a conductor, is the device's anode; the platinum, which sits atop the electrolyte, is the cathode.

A more efficient DSSC would use a material like acetonitrile for the electrolyte. However, this material does not lend itself to the production of a stable solar cell that could be commercially marketed. Instead, a low-volatility solvent is typically used, but this comes at the price of being more viscous and impeding the flow of ions.

The novel quasi-liquid electrolyte that the KTH researchers have developed delivers the best of all worlds: overcoming the viscosity problem, improving the flow of electrons, and doing so at a much lower volatility than can be achieved with acetonitrile.

“We now have clear evidence that by adding [a special] ion-conducting polymer to the solar cell’s cobalt redox electrolyte, the transport of oxidized electrolytes is greatly enhanced,” said James Gardner, a professor of photoelectrochemistry at KTH, in a press release. “The fast transport increases solar cell efficiency by 20 percent.”

With conversion efficiencies for DSSCs already having already reached the 10 percent mark, this would boost efficiency to around 12 percent.

These are impressive numbers, but perhaps a more beneficial characteristic—at least for the economics of DSSCs—would be a longer lifespan. With this new electrolyte, DSSCs could have a longer lifespan, making it possible to amortize the cost of the initial installation over a greater period of time. It's not clear how much more life could be added to the DSSCs, but every bit counts.

Photo: David Callahan




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
New York City
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