Friday, February 27, 2009

upcoming speaker...

Mark your calendars....

Hedi Mattoussi from the Naval Research Lab in D.C. will be on campus on Monday April 20th to give a seminar.  Time is TBA but this will be part of the Inorganic Chemistry seminar and will probably start around 3-4pm in PSBN 4606 or Chem 1005D.

He does synthesis and modification of quantum dots, specifically working with applications for water-soluble quantum dots.

Emerging Technologies/Emerging Economies Conference

I didn't have time to update everyone at the meeting, but the website for the Conference on Emerging Economies/Emerging Technologies is now available (click here for link).

Rachel Parker from CNS came to talk to us a few weeks ago about the conference which is scheduled for Nov 4-9, 2009 in D.C.

I know some of you seemed interested, and as Rachel indicated, there will be a section "Meeting Energy Demands Through Emerging Technologies" that I think we as IGERT fellows would really benefit from learning at.

Let me know if/when you want to meet to discuss how we can participate.


Not Quite Energy Conversion... but cupcakes!

There was a very interesting presentation today in the IV theater which worked just as well as a sales pitch as it did as an informative discussion (I bought one of the T-shirts). Johnny Cupcakes was clearly an entrepreneur from an early age, something which he seemed proud to point out. He seemed to also get a kick out of the simplicity of his product offering. He began his presentation by stating that he would tell us how he “started a multi-million dollar company with no education and selling t-shirts with cupcakes on them.” This idea kept me interested and I think that he made a number of very important points, which I will try to point out.

Johnny’s story began by discussing many of his childhood antics. He highlighted some of his early entrepreneurial adventures by pointing out the classic example of running lemonade stand as a child, noting that a few dollars as a child felt like what a few hundred would now. His entrepreneurial behavior continued into high school where he began buying prank supplies and candy wholesale and then selling them to other high school students. These ventures ended however when someone had an allergic reaction to some of the itching powder he was selling and his candy sales began to interfere with the schools own sale of candy. At this point he graduated high school and gave college a try. College wasn’t his thing and he left. He began making buttons with a $100 button machine he bought online for bands and other events and selling them. He got a partner to help him with this but then his partner got a girlfriend and the business eroded. Later, he took job at a record store where people frequently called him Johnny wrench, Johnny record, Johnny cupcake etc. It was Johnny cupcake which stuck, and since he was in a band at the time which was making t-shirts to promote their music he threw in an additional order for a t-shit which just said Johnny Cupcake. After receiving several comments on the shirt he decided to have more made and began selling them out of the back of his crappy car while working at the record shop. He wore the shirt at his concerts and they were a hit, people, and members of other bands wanted to buy them.

Interestingly Johnny started realizing that these t-shirts could become a lucrative business as he was making more money selling them than he was working in the record shop. He quit his job and began selling the shirts while on tour with the band to local clothing companies where he was touring. Many of the clothing companies took orders and at this point he made the decision that he had to go 110% one direction. He could either go 110% towards the band, or 110% toward the Jonny Cupcakes shirts. Since he was tired of sleeping on the floor with a bunch of other lonely guys he decided he would continue full force with the t-shirt company. At this point he had come up with many more designs and had many different t-shirt design offerings.

As he continued to make sales people would ask him whether he was going to be at this tradeshow or at that tradeshow, he had no idea what a trade show even was so looked it up and decided that he would like to try it. At the trade show he mentioned that there were many offers to buy his shirts from large companies like Urban Outfitters and Nordstrom but at this point he made what seems like a crucial realization. He noticed that two kids at the tradeshow had the exact same shoes as him and though about how much “it sucked” when someone had the same thing as you and he mentioned the idea of girls at a prom with the same prom dress. At this point he decided to rip up the orders from the large companies and decided that he did not want to mass market his product.

In order to continue sale of his product he set up a website which took orders and he began the process of getting an office near his home out of which he could sell, store, and ship orders. He commented that the ability to do all of these things out the same space saved a lot of money and helped him take his focus off of things that weren’t going so well since he could always put his attention into something else since it was all right there in one place. He continually commented on how well viral marketing worked in his favor, “one person told ten people, ten people told a hundred people, he kept repeating. He used this idea in his marketing as well. He opted not to spend money on advertising, but rather to keep that money in the business by putting it into new products or some promotion somewhere.

The viral marketing worked and as he opened up a store in a larger city outside of Boston more than 400 people lined up to be the first to buy the shirts. He commented on how much time he spent on the actual design of the store, and how people told him he was crazy to move from his low rent office space near his home for $700 a month to the new space which cost $7000 a month. Obviously biting the bullet and going for it, “taking the risk” as he put it, worked for him and his sales increased tremendously. He said that he sold enough t-shirts the first day to cover a month’s rent. He got a lot of free advertising from the media who came in and wanted to share his story, he even made the front page of several papers! He again took a large risk when he went to open up a Los Angeles store way across the country. He took 6 months to get the store design perfect, commenting on the special features of his design and how much thought actually went into the layout. Again, his meticulous planning and habit for risk taking worked out and he sold enough t-shirts on the opening day to pay 5 of the 6 months rent that he had had to pay while developing the store.

He made several comments about the importance of packaging saying that it is really like free advertising for you and that people will keep it around their office, room, etc. contributing to the viral marketing. On the best things that I think he said during the talk was that you need to pick something and go 110% after that. “If you are in a relationship, going to school, trying to start a company, and partying with friends you are really just half-assing four things.” That was my biggest take away from this talk. It was interesting to me that he does not drink and has never done drugs so he really does put all of his time into his business but it seems to be very rewarding for him, and his story is inspiring. One other thing that I found interesting was how he quantified having a girlfriend. Saying that well, I would normally work until about 3am but when I had a girlfriend we would hang out do dinner and a movie and then go to bed and “considering that I would meet her at about noon and do this 3 days a week I was really losing about 40 hours of working time a week.” “I still love her and think about her and always wanted to make her happy but I just don’t have enough time right now to worry about someone else besides myself and my business. I think that this was an interesting note to end on and really illustrated how devoted he was to this business and to his customers, noting that “he wouldn’t sell his company for all the money in the world.” This was a refreshing idea in today’s business climate where people are often too busy looking at dollar signs to see those other things of value.

Anyway, I know this is very unrelated to energy conversion but I found it very informative and inspiring.

Monday, February 23, 2009

Electron Diffractive Imaging: Full 3D reconstructions of aperiodic structures

This may be an interesting way to look nanoparticles for catalysis since we should have this capability on campus.


Posted: February 18, 2009
New imaging technique reveals the atomic structure of nanocrystals
(Nanowerk News) A new imaging technique developed by researchers at the University of Illinois overcomes the limit of diffraction and can reveal the atomic structure of a single nanocrystal with a resolution of less than one angstrom (less than one hundredth-millionth of a centimeter).
Optical and electronic properties of small assemblages of atoms called quantum dots depend upon their electronic structure – not just what's on the surface, but also what's inside. While scientists can calculate the electronic structure, they need to know where the atoms are positioned in order to do so accurately.
Getting this information, however, has proved to be a challenge for nanocrystals like quantum dots. Mapping out the positions of atoms requires clues provided by the diffraction pattern. But quantum dots are so small, the clues provided by diffraction alone are not enough.
By combining two sources of information – images and diffraction patterns taken with the same electron microscope – researchers at the U. of I. can achieve sub-angstrom resolution of structures that were not possible before.
"We show that for cadmium-sulfide nanocrystals, the improved image resolution allows a determination of their atomic structures," said Jian-Min (Jim) Zuo, a professor of materials science and engineering at the U. of I., and corresponding author of a paper that describes the high-resolution imaging system in the February issue of Nature Physics.
Images from electron microscopy can resolve individual atoms in a nanocrystal, but the atoms soon suffer radiation damage, which limits the length of observations. Patterns from X-ray diffraction can be used to determine the structure of large crystals, but not for nanocrystals, which are too small and don't diffract well.
To achieve sub-angstrom resolution, Zuo and colleagues developed a reiterative algorithm that processes and combines shape information from the low-resolution image and structure information from the high-resolution diffraction pattern. Both the image and the diffraction pattern are taken with the same transmission-electron microscope.
"The low-resolution image provides the starting point by supplying missing information in the central beam and supplying essential marks for aligning the diffraction pattern," said Zuo, who also is a researcher at the university's Frederick Seitz Materials Research Laboratory. "Our phase-retrieval algorithm then reconstructs the image."
To demonstrate the technique, the researchers took a new look at cadmium-sulfide quantum dots.
"We chose cadmium-sulfide quantum dots because of their size-dependent optical and electronic properties, and the importance of atomic structure on these properties," Zuo said. "Cadmium-sulfide quantum dots have potential applications in solar energy conversion and in medical imaging."
Using the reiterative algorithm, the smallest separation between the cadmium and sulfide atomic columns was measured at 0.84 angstroms, the researchers report.
"Since low-resolution images can be obtained from different sources, our technique is general and can be applied to non-periodic structures, such as interfaces and local defects," Zuo said. "Our technique also provides a basis for imaging the three-dimensional structure of single nanoparticles."
Source: University of Illinois at Urbana-Champaign

Tuesday, February 17, 2009

Putting Metal in Cages

Interesting work by Bazan and co-workers.... This might also serve as a great experimental tool.


Luna Innovations' Research on Solar Cell Technology is Published in Nature Materials
Research Shows Promise for Organic Photovoltaic Solar Cells as Alternative Energy Source

ROANOKE, Va.--(BUSINESS WIRE)--Feb. 11, 2009-- Luna Innovations Incorporated (NASDAQ:LUNA) announces the solar cell research of scientists Dr. Claudia Cardona and Dr. Martin Drees has been published in the prestigious journal Nature Materials. The paper titled "Endohedral fullerenes for organic photovoltaic devices" presents a unique approach to enhance flexible, plastic solar cells, also known as organic photovoltaic (OPV) cells, by modifying the acceptor material rather than the donor material. The paper, which is co-authored by researchers from Georgetown University, University of California at Santa Barbara, the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) and Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany, describes how the efficiency improvement was achieved through the use of Luna’s carbon nanomaterials.

“Organic solar cells offer the potential for clean, renewable energy at an affordable price,” said Kent Murphy, Chairman and CEO of Luna Innovations. “These exciting energy harvesting devices can change the way we convert sunlight to electricity. Because they are flexible and easy to handle, they have potential for use in mobile communication devices, consumer electronics, fabrics, building materials, and more. An improvement in efficiency through the use of a novel acceptor molecule is unique to the industry and could enable solar cell manufacturers to increase performance and reduce costs.”

Organic solar cells are made out of plastic-like polymers that serve as electron donors and are combined with fullerene nanomaterials, which serve as electron acceptors. Organic solar cells weigh less and are cheaper to manufacture compared to conventional inorganic silicon-based solar cells, which are presently favored by the solar industry. An existing disadvantage of organic solar cells is the efficiency at which they convert sunlight to electricity. Luna’s solar cells use patented carbon nanomaterials to capture more energy in the photovoltaic process, which increases the organic solar cell efficiency.

“Our research demonstrates an entirely new approach of enhancing OPV device performance by using improved acceptor materials, and expands an area of OPV research that has remained relatively stagnant over the last decade,” said Dr. Drees. “Luna’s novel acceptor materials operate at high conversion efficiencies and are an excellent complement to the fast growing semi-conductive-polymer field. This demonstration is a significant advancement towards making practical organic solar cell devices.”

This paper is an example of Luna’s work in materials that could produce alternative energy forms. The company is focusing on integrating its carbon nanomaterial technology into the products of solar cell manufacturers making commercially viable products. Luna’s nanomaterials have been independently verified at NREL as setting a new record for efficiency of the commercially available P3HT organic solar cell polymer. Luna continues its work to further optimize organic solar cell performance through government-funded technology development programs.

Luna’s research efforts were supported by the National Science Foundation and Air Force Office of Scientific Research.

The paper in Nature Materials was scheduled for Advance Online Publication at, beginning on February 8, 2009. Papers published online before they have been allocated to a print issue are citable via a digital object identifier (DOI) number. The DOI for this paper is 10.1038/nmat2379. Once the paper is published electronically, the DOI can be used to retrieve the abstract and full text (abstracts are available to everyone, full text only to subscribers) by adding it to the following URL:

Thursday, February 12, 2009

Multiple Exiton Generation: Fact or Fiction?

Thanks to my Mom for forwarding this article! Came to me under the heading: Thought you would like to read this -love, mom.


Posted: February 10, 2009
Improving solar cells - Certain nanocrystals shown to generate more than one electron
(Nanowerk News) A team of Los Alamos researchers led by Victor Klimov has shown that carrier multiplication—when a photon creates multiple electrons—is a real phenomenon in tiny semiconductor crystals and not a false observation born of extraneous effects that mimic carrier multiplication. The research, explained in a recent issue of Accounts of Chemical Research, shows the possibility of solar cells that create more than one unit of energy per photon.
Questions about the ability to increase the energy output of solar cells have prompted Los Alamos National Laboratory researchers to reassess carrier multiplication in extremely small semiconductor particles.
When a conventional solar cell absorbs a photon of light, it frees an electron to generate an electrical current. Energy in excess of the amount needed to promote an electron into a conducting state is lost as heat to atomic vibrations (phonons) in the material lattice. Through carrier multiplication, excess energy can be transferred to another electron instead of the material lattice, freeing it to generate electrical current—thereby yielding a more efficient solar cell.
Klimov and colleagues have shown that nanocrystals of certain semiconductor materials can generate more than one electron after absorbing a photon. This is partly due to strengthened interactions between electrons squeezed together within the confines of the nanoscale particles.
In 2004, Los Alamos researchers Richard Schaller and Klimov reported the first observations of strong carrier multiplication in nanosized crystals of lead selenide resulting in up to two electron-hole pairs per absorbed photon. A year later, Arthur Nozik and coworkers at the National Renewable Energy Laboratory reproduced these results. Eventually, spectroscopic signatures of carrier multiplication were observed in nanocrystals of various compositions, including silicon.
Recently, the claims in carrier multiplication research have become contentious. Specifically, some recent studies described low or negligible carrier multiplication efficiencies, which seemed to run contrary to earlier findings. To sort out these discrepancies, Los Alamos researchers analyzed factors that could have led to a spread in the reported carrier multiplication results. These factors included variations between samples, differences in detection techniques, and effects mimicking the signatures of carrier multiplication in spectroscopic measurements.
To analyze how a particular detection technique might affect an outcome, John McGuire, a postdoctoral researcher on Klimov's team, investigated carrier multiplication using two different spectroscopic techniques—transient absorption and time-resolved photoluminescence. The results obtained by these two methods were in remarkable agreement, indicating that the use of different detection techniques is unlikely to explain discrepancies highlighted by other researchers. Further, although these measurements revealed some sample-to-sample variation in carrier multiplication yields, these variations were much smaller than the spread in reported data.
After ruling out these two potential causes of discrepancies, the researchers focused on effects that could mimic carrier multiplication. One such effect is photoionization of nanocrystals.
"When a nanocrystal absorbs a high-energy photon, an electron can acquire enough energy to escape the material," Klimov explained. "This leaves behind a charged nanocrystal, which contains a positive 'hole.' Photogeneration of another electron by a second photon results in a two-hole, one-electron state, reminiscent of one produced by carrier multiplication, which can lead to false positives," he said.
To evaluate the influence of photoionization, the Los Alamos researchers conducted back-to-back studies of static and stirred solutions of nanocrystals. Stirring removes charged nanocrystals from the measured region of the sample. Therefore, when crystals are subjected to light, the stirring eliminates the possibility that charged nanocrystals will absorb a second photon. While stirring of some samples did not affect the results of the measurements, other samples showed a significant difference in the apparent carrier multiplication yields measured under static and stirred conditions. Since most previous studies were performed on static samples, these results suggest that discrepancies noted by other researchers arise at least in part from uncontrolled photoionization, which stirring seeks to eliminate.
The Los Alamos researchers re-evaluated carrier multiplication efficiencies when photoionization was suppressed. The results are encouraging.
While the newly measured electron yields are lower than previously reported, the efficiency of carrier multiplication is still greater than in bulk solids. Specifically, both the energetic onset and the energy required to generate an extra electron in nanocrystals are about half of those in bulk solids.
These results indicate significant promise for nanosized crystals as efficient harvesters of solar radiation.
"Researchers still have a lot of work to do," Klimov cautioned. "One important challenge is to figure out how to design a material in which the energetic cost to create an extra electron can approach the limit defined by a semiconductor band gap. Such a material could raise the fundamental power conversion limit of a solar cell from 31 percent to above 40 percent."
Source: DOE/Los Alamos National Laboratory