AUSTIN, Texas—Conventional solar cell efficiency could be increased from the current limit of 30 percent to more than 60 percent, suggests new research on semiconductor nanocrystals, or quantum dots, led by chemist Xiaoyang Zhu at The University of Texas at Austin.

Xiaoyang ZhuChemistry Professor Xiaoyang Zhu. Photo by Marsha Miller.

Zhu and his colleagues report their results in this week’s Science.

The scientists have discovered a method to capture the higher energy sunlight that is lost as heat in conventional solar cells.

The maximum efficiency of the silicon solar cell in use today is about 31 percent. That’s because much of the energy from sunlight hitting a solar cell is too high to be turned into usable electricity. That energy, in the form of so-called “hot electrons,” is lost as heat.

If the higher energy sunlight, or more specifically the hot electrons, could be captured, solar-to-electric power conversion efficiency could be increased theoretically to as high as 66 percent.

“There are a few steps needed to create what I call this ‘ultimate solar cell,’” says Zhu, professor of chemistry and director of the Center for Materials Chemistry. “First, the cooling rate of hot electrons needs to be slowed down. Second, we need to be able to grab those hot electrons and use them quickly before they lose all of their energy.”

Zhu says that semiconductor nanocrystals, or quantum dots, are promising for these purposes.

As for the first problem, a number of research groups have suggested that cooling of hot electrons can be slowed down in semiconductor nanocrystals. In a 2008 paper in Science, a research group from the University of Chicago showed this to be true unambiguously for colloidal semiconductor nanocrystals.

Illustration of hot electron transfer in solar cell

Zhu’s team has now figured out the next critical step: how to take those electrons out.

They discovered that hot electrons can be transferred from photo-excited lead selenide nanocrystals to an electron conductor made of widely used titanium dioxide.

“If we take the hot electrons out, we can do work with them,” says Zhu. “The demonstration of this hot electron transfer establishes that a highly efficient hot carrier solar cell is not just a theoretical concept, but an experimental possibility.”

The researchers used quantum dots made of lead selenide, but Zhu says that their methods will work for quantum dots made of other materials, too.

He cautions that this is just one scientific step, and that more science and a lot of engineering need to be done before the world sees a 66 percent efficient solar cell.

In particular, there’s a third piece of the science puzzle that Zhu is working on: connecting to an electrical conducting wire.

“If we take out electrons from the solar cell that are this fast, or hot, we also lose energy in the wire as heat,” says Zhu. “Our next goal is to adjust the chemistry at the interface to the conducting wire so that we can minimize this additional energy loss. We want to capture most of the energy of sunlight. That’s the ultimate solar cell.

“Fossil fuels come at a great environmental cost,” says Zhu. “There is no reason that we cannot be using solar energy 100 percent within 50 years.”

Funding for this research was provided by the U.S. Department of Energy. Coauthors include William Tisdale, Brooke Timp, David Norris and Eray Aydil from the University of Minnesota, and Kenrick Williams from The University of Texas at Austin.

For more information contact: Dr. Xiaoyang Zhu, professor of chemistry, 512-471-9914; Lee Clippard, public affairs, 512-232-0675.



Aug 12, 2010 (The Hartford Courant – McClatchy-Tribune Information Services via COMTEX) —

The tiny crevices of butterfly wings are the ideal design for nanotechnology that could make subway stations safer, according to scientists at Fairfield-based General Electric Co.

Three years ago, GE scientists learned that scales on butterflies wings have little nooks aligned in a manner that is perfect for sensing tiny particles of chemicals. GE then replicated the butterfly wings with nanotechnology to sense chemicals in bombs. The resulting technology could be used to detect chemicals in subway stations or other public places.

The equipment could also be used for monitoring emissions at power plants, food-and-beverage safety, water purification testing, breath analysis to detect diseases and assessing how well wounds are healing.

On Thursday, the Defense Advanced Research Projects Agency gave a four-year, $6.3 million award to a group of scientists including those at GE Global Research, the State University of New York-Albany, University of Exeter, and Air Force Research Laboratory to develop nanotechnology devices that will more quickly and accurately detect chemicals used in explosives or other implements of war.

“We have been greatly inspired by examples of naturally occurring optical structures whose properties arise from an intricate morphology,” said Defense Advanced Research Projects Agency program manager Viktoria Greanya. “For example, the brilliant colors seen in butterfly wings, beetle carapaces, and peacock feathers are due in large part to their complex structure, not simply their color.”

For perspective, GE researchers say a nanometer is relative in size to a tennis ball as a tennis ball is to the size of Earth.

“GE’s bio-inspired sensing platform could dramatically increase sensitivity, speed and accuracy for detecting dangerous chemical threats,” said Radislav Potyrailo, a principal scientist at GE Global Research. “All of these factors are critical, not only from the standpoint of preventing exposure, but in monitoring an effective medical response if necessary to deal with such threats.”

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Shaping memory materials

Nanotechnology introduced the techniques to distort the plastic and silicon structures, which allowed the recovering of original shape of the material. This technology is named as SMM shaping memory materials. Metals and aluminum are reshaped and processed at nano scale to produce a chip, which can store bulk of information on it. Aluminum and silicon distortion was impossible before the arrival of nanotechnology

Assemblies and Chemical sensitivity of porphyrin

Porphyrins is the element with the unique binding properties that are widely exploited in natural world to attain beneficial and essential functions for life, nanotechnology has provided the most accurate and real some the mimic of these functions with synthetic counterparts which provides the basis of chemical bonding and sensitizing

Metal oxide nanowires as chemical sensors

Another impressive feature of nanotechnology is that it made possible for the scientists to use metal oxides as the sensors. When metal are treated at nano scale they can carry huge amount of electrons and can be used as chemical sensors. , this was discovered in early nineties and nanowires were introduced.

Use of nanomaterials for water purification

Nanotechnology allowed the researchers to process the materials to be used in purification of drinking water such as sand, soil and even glass. Nano filtration plants are present in the developed countries of the world. Nanomaterials can purify water up to 99.9 percent without affecting the original flavor the water. it was seen for the first time that nanotechnology can extract the safest drinking water.


Self-assembling the key feature of nanotechnology .there is no other technology in which molecules under processing can rearrange themselves easily. Molecular nanotechnology can produce many new components from the existing ones by simply rearranging themselves.

Miniaturizing mechanical surgery

Recent advances in sub-millimeter scale engineering showed the excellent work of nanotechnology in the field of medical sciences .nanotechnology introduced such devices, which do not even leave a scar after major surgeries. it has also miniaturized the surgical instruments which are used in the diagnostics and therapeutics applications.

Fabrication of electronic biosensors

Nanotechnology introduced the nano fabrications, which has reduced the cost of some of the major health equipment that includes electronic biosensors. Detection biosensors, which are nanoly, structured detect and displays highly revolutionized images.

New carbon nanotubes AFM technology

Nanotechnology also ha great value in the field of nuclear sciences because of its extra ordinary features to increase the atomic force. it was discovered in mid nineties that uranium if processed at nano level can empower the five times more powerful nuclear bomb. Nanotechnology enlighten the nano particle of carbon, .nanotubes of carbon are used to build ultra sharp tips for cutting the rigid surfaces. The technology of the new carbon tubes is named as AFM (Atomic Force Microscopy). The technology is used for the fabrication of probe tips with ultra sharp points .AFM is also used for synthesizing and for developing new components.

General Purpose technology

Nanotechnology can create machines, peripheral home appliances with best functioning until now. It is the only technology, which is general purpose. From Light Emitting Diodes (LEDs) to socks, all are processed at atomic scale for increasing and improving the quality of the product.

  • One of the biggest disadvantage that world is facing because of nanotechnology is the lack of employment in the fields of traditional farming and manufacturing and industrial sector because of the vast development in the nanotechnology .nanotech devices and machines have taken place of human to work  faster and accurately which has lessen the importance of men power in the field of practical work
  • Increasing development and instant performance has also increased the fall of certain markets like diamond and oil because of the low value of diamond and oil .Presence of alternative has decreased the demand because alternates are more efficient and do not require the use of fossil fuels. Diamonds have lost its value because it is now produced massively with the help of nanotechnology.  People and manufacturer can now produce bulk of the products at molecular scale and decomposition is done to create new components.
  • Another big threat, which is born with the advent of nanotechnology, is the easy accessibility of atomic weapons. Nanotechnology has made these weapons more powerful and more destructive .unauthorized, criminal bodies can reach nuclear weapons easily, and its formulation could be stolen.
  • Nanotechnology has increased risk to the health also , nanoparticles due to there their small size can cause inhalation problem and many other fatal diseases. by just inhaling for 60  seconds  in the air contain nano particles can damage lungs easily.
  • At present nanotechnology is on the most expensive technologies and its cost is increasing day by day. The main reason for very high cost is the molecular structure and processing of the product.  It quite difficult of the manufacturers to randomly produce dynamic products with the nanotechnology. Huge pricing of nanotech machines make it unaffordable for the common people.
  • Working with nanotechnology is quite risky also, Manufacturers have to invest huge money for starting nanotech plants and if products produced is fail to satisfy the customer then manufacturer bear a lot of loss. The original product cannot be recovered because it will cost double to the manufacturers.  Maintenance cost of the product is also very high.
  • Nanotechnology also raised some practical problems. Practical problems can include everything which is to be produced from masses like coal, petroleum,. Nanotechnology does not leave single nano particle unused which crashed the small industries of  sub products of the massive materials this is the main reason for low quantity of sub products of coal and petroleum in the markets
  • there are also some ethical issues which include the poisoning of mass material which has been processed at nano scale .this may leave negative impacts on the health and industry. Mass poisoning could happen only if the coatings on the products  that nanotechnology has to produce include poisonous micro particles that can penetrate into the brain
  • While nanotechnology can produce all kinds of new and improved products but, the particles that are created are so small that they may cause eventual health problems in the bodies of consumers who use these products that use them.
  • Nanotechnology has raised the standard of living but at the same time, it has increased the pollution, which includes water pollution, air pollution. The pollution caused by nanotechnology is known as nano pollution. This kind of pollution is very dangerous for living organisms.

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DECEMBER 14-18TH, 2010

ACMS Conference Room

Indian Institute of Technology, Kanpur

for more details


Posted: August 13, 2010 in uPcoMinG eVeNts iN INdIA

Event Description

The theme of the conference Nanotech India 2010 is “A Nano Smart World”. Nanotech India 2010 is to gather scholars and researchers from all over the world to present advances in the field of nanotechnology and to foster an environment conducive to exchanging ideas and information. This conference will also provide a golden opportunity to develop new collaborations and meet world experts on the fundamentals, applications and products of nanotechnology,

Time: November 19, 2010 to November 21, 2010
Event Type: internationalconfrencea nano smart world

Event Description

Carbon materials are enabling materials for a number of structural applications in space, missile, aircraft, nuclear, power generation, ground transportation in addition to environmental and chemical industries, where demanding reliable performance in adverse environment is critically needed. Significant progress has been made in the area related to research, design, development, testing and commercialization of these materials all over the world. However, significant challenges continue to remain, for achieving further advancements in the properties of these materials for maximum utility and widespread use. This has been the main driving force for holding conferences around the globe on Carbon Nanotechnology: Potential and Challenges for 21st century, bringing together academicians and researchers in various disciplines to share the knowledge and exchange views for useful industrial applications of these materials.

Sub Theme

1. Carbon Nanofiber
2. Carbon Nanotube
3. Carbon based Fullerence
4. Other Forms of Carbon i.e., Diamond, Amorphous carbon, Graphite
5. Carbon-Carbon Composites
6. Carbon-Silicon Composites
7. Carbon Nanotube Reinforced Ceramic Matrix Composites
8. Carbon Nanotube Reinforced Metal Matrix Composites
9. Carbon Nanotube Reinforced Polymer Matrix Composites
10. Carbon Nanotube and its Composites: Modeling
11. Carbon: Biomaterials
12. Carbon: Fuel Cell
13. Carbon: Nuclear
14. Carbon: Photovoltaic Cell
15. Carbon: Smart Materials
16. Carbon: Space
17. Carbon: Automobile
18. Other Engineering Applications of Carbon
19. Nondestructive Testing

Time: December 15, 2010 to December 17, 2010
Location: Indian Institute of Technology ,Kanpur,India
City/Town: Kanpur,Uttar Pradesh ,India
Website or Map:
Event Type: conference
Organized By: IIT Kanpur

When loaded with an anticancer drug, a delivery system based on a novel material that its creators call a nanosponge is three to five times more effective at reducing tumour growth than direct injection of the same drug. That is the conclusion of a paper published in the journal Cancer Research (“Targeted Nanoparticles That Deliver a Sustained, Specific Release of Paclitaxel to Irradiated Tumors”).

“Effective targeted drug delivery systems have been a dream for a long time now, but it has been largely frustrated by the complex chemistry that is involved,” says Eva Harth of Vanderbilt, who led the nanosponge development team. “We have taken a significant step toward overcoming these obstacles.” The current study was a collaboration between Harth’s laboratory and that of Dennis Hallahan at the Washington University School of Medicine and Roberto Diaz at Emory University.
“We call the material nanosponge, but it is really more like a three-dimensional network or scaffold,” says Harth. The backbone is a long length of polyester. It is mixed in solution with small molecules called cross-linkers that act like tiny grappling hooks to fasten different parts of the polymer together. The net effect is to form spherically shaped particles filled with cavities where drug molecules can be stored. The polyester is biodegradable, so it breaks down gradually in the body. As it does, it releases the drug it is carrying in a predictable fashion.
“Predictable release is one of the major advantages of this system compared to other nanoparticle delivery systems under development,” says Harth. When they reach their target, many other systems unload most of their drug in a rapid and uncontrollable fashion. This is called the burst effect and makes it difficult to determine effective dosage levels.
Another major advantage is that the nanosponge particles are soluble in water. Encapsulating the anti-cancer drug in the nanosponge allows the use of hydrophobic drugs that do not dissolve readily in water. Currently, these drugs must be mixed with another chemical, called an adjuvant reagent, which reduces the efficacy of the drug and can have adverse side- effects.
It is also possible to control the size of nanosponge particles. By varying the proportion of cross-linker to polymer, the nanosponge particles can be made larger or smaller. This is important because research has shown that drug delivery systems work best when they are smaller than 100 nanometers. The nanosponge particles used in the current study were 50 nanometers in size.
The targeting peptide used in the animal studies was developed by the Hallahan laboratory, which also tested the system’s effectiveness in tumor-bearing mice. The peptide used in the study is one that selectively binds to a protein found on tumors that have been treated with radiation. The researchers used the nanoparticles to deliver paclitaxel to tumours in this study. The researchers recorded the response of two different tumor types – slow-growing human breast cancer and fast-acting mouse glioma – to single injections. In both cases they found that it increased the death of cancer cells and delayed tumor growth “in a manner superior to known chemotherapy approaches.”
The next step is to perform an experiment with repeated injections to see if the nanosponge system can stop and reverse tumor growth. Harth is also planning to perform the more comprehensive toxicity studies on her nanoparticle delivery system that are required before it can be used in clinical trials.

Source: National Cancer Institute

Call it the anti-sunscreen. That’s more or less the description of what many solar energy researchers would like to find — light-catching substances that could be added to photovoltaic materials in order to convert more of the sun’s energy into carbon-free electricity.

Research reported in the journal Applied Physics Letters, published by the American Institute of Physics (AIP), describes how solar power could potentially be harvested by using oxide materials that contain the element selenium. A team at the Lawrence Berkeley National Laboratory in Berkeley, California, embedded selenium in zinc oxide, a relatively inexpensive material that could be promising for solar power conversion if it could make more efficient use of the sun’s energy. The team found that even a relatively small amount of selenium, just 9 percent of the mostly zinc-oxide base, dramatically boosted the material’s efficiency in absorbing light.

“Researchers are exploring ways to make solar cells both less expensive and more efficient; this result potentially addresses both of those needs,” says author Marie Mayer, a fourth-year University of California, Berkeley doctoral student based out of LBNL’s Solar Materials Energy Research Group, which is working on novel materials for sustainable clean-energy sources.

Mayer says that photoelectrochemical water splitting, using energy from the sun to cleave water into hydrogen and oxygen gases, could potentially be the most exciting future application for her work. Harnessing this reaction is key to the eventual production of zero-emission hydrogen powered vehicles, which hypothetically will run only on water and sunlight. Like most researchers, Mayer isn’t predicting hydrogen cars on the roads in any meaningful numbers soon. Still, the great thing about solar power, she says, is that “if you can dream it, someone is trying to research it.”

Source: American Institute of Physics

Germany: PhD Position at Max Planck Institute of Quantum Optics, Garching

October 13, 2009 by info
Filed under: Another Fellowships

PhD position at Max Planck Institute of Quantum Optics, Garching Germany

PhD positions are available in the Max Planck Institute of Quantum Optics in the laser spectroscopy division of Prof. T. Hänsch.

The aim of this project is to explore the potential of frequency comb based Fourier transform spectroscopy. The work will be performed in close collaboration with the Laboratoire de Photophysique Moleculaire of the CNRS in Orsay. More information can be found on the following website.