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Tag Archives: University of Toronto
Squashed quantum dots solve a multi-faceted problem – Optoelectronics
Oblate-shaped quantum dots
Quantum dots have revolutionized the field of optoelectronics due to their atom-like electronic structure. However, the prospect of colloidal quantum-dot lasers has long been deemed impractical due to the high energies required to induce optical gain. But recent work published in Nature and led by Ted Sargent of the University of Toronto shows that the lasing threshold in cadmium selenide (CdSe)/cadmium sulphide (CdS) core-shell colloidal quantum dots can be lowered by squashing the CdSe core via a clever ligand exchange process.
To instigate optical gain in a semiconductor laser, the difference between the lowest electron level and the highest hole level must be wider than the band gap so that the light emitted when they recombine can stimulate emission in neighbouring nanocrystals. Colloidal quantum dots (CQDs) then, should make ideal candidates for lasing applications, as their atom-like electronic structure means that the electron and hole energy levels are easier to separate.
In practice, however, the energies required to trigger optical gain in CQDs are so high that they can heat up to the point of burning. While electrons tend to occupy one energy state upon excitation, the hole that they leave behind in the valence band can populate one of eight closely spaced states. This degeneracy pushes the hole Fermi level into the band gap and increases the amount of energy required to instigate optical gain.
To overcome this issue, the researchers took advantage of the fact that CdS imposes a strain on CdSe due to a slight lattice mismatch of 3.9%. By growing an asymmetric CdS shell around a "squashed" oblate CdSe core, they were able to induce a biaxial strain that affected the heavy and light holes of the valence band to different extents, thus lifting the degeneracy.
To produce these asymmetric CQDs the group invented a technique called facet-selective epitaxy, making use of ligands that interact differently with the surfaces of CdSe. One of these ligands, trioctylphosphine sulphide, or TOPS, binds weakly to the (0001) facet of CdSe and not at all to the (0001), while octanethiol interacts similarly with all CdSe surfaces. Therefore, by growing CdS on the (0001) facet with TOPS and then replacing with octanethiol to stimulate epitaxial growth, oblate-shaped CQDs could be made throughout the entire particle ensemble with remarkable uniformity.
The resulting lasers had an unprecedentedly high performance, exhibiting a low lasing threshold of 6.4–8.4 kW cm–2, a seven-fold reduction compared with previous attempts. They also emitted light over a narrow energy range of just 36 meV. Both of these properties can be attributed to the enhanced splitting of the valence band levels that arises due to the oblate CQD shape.
The international team of researchers has certainly proved that continuous-wave CQD lasers are possible, yet there are still some obstacles to be overcome before they are seen on the market. Most importantly, the next step will be exciting the CQDs via electrical rather than optical means, as in standard commercial lasers. Nevertheless, facet-selective epitaxy opens up a whole host of other CQD materials for lasing applications and beyond.
Leave a comment Posted in Nanotechnology Tagged Genesis Nanotechnology, Nanomaterials, Nanotechnology, Quantum Dots, Ted Sargent, University of Toronto
U of Toronto: A Printable Solar Cell Closer to Commercial Reality
A University of Toronto Engineering innovation could make printing solar cells as easy and inexpensive as printing a newspaper.
Dr. Hairen Tan and his team have cleared a critical manufacturing hurdle in the development of a relatively new class of solar devices called perovskite solar cells. This alternative solar technology could lead to low-cost, printable solar panels capable of turning nearly any surface into a power generator.
"Economies of scale have greatly reduced the cost of silicon manufacturing," said Professor Ted Sargent, an expert in emerging solar technologies and the Canada Research Chair in Nanotechnology. "Perovskite solar cells can enable us to use techniques already established in the printing industry to produce solar cells at very low cost. Potentially, perovskites and silicon cells can be married to improve efficiency further, but only with advances in low-temperature processes."
The new perovskite solar cells have achieved an efficiency of 20.1 per cent and can be manufactured at low temperatures, which reduces the cost and expands the number of possible applications. (Image: Kevin Soobrian)
Today, virtually all commercial solar cells are made from thin slices of crystalline silicon which must be processed to a very high purity. It's an energy-intensive process, requiring temperatures higher than 1,000 degrees Celsius and large amounts of hazardous solvents.
In contrast, perovskite solar cells depend on a layer of tiny crystals — each about 1,000 times smaller than the width of a human hair — made of low-cost, light-sensitive materials. Because the perovskite raw materials can be mixed into a liquid to form a kind of 'solar ink', they could be printed onto glass, plastic or other materials using a simple inkjet printing process.
But, until now, there's been a catch: in order to generate electricity, electrons excited by solar energy must be extracted from the crystals so they can flow through a circuit. That extraction happens in a special layer called the electron selective layer, or ESL. The difficulty of manufacturing a good ESL has been one of the key challenges holding back the development of perovskite solar cell devices.
"The most effective materials for making ESLs start as a powder and have to be baked at high temperatures, above 500 degrees Celsius," said Tan. "You can't put that on top of a sheet of flexible plastic or on a fully fabricated silicon cell — it will just melt."
Tan and his colleagues developed a new chemical reaction than enables them to grow an ESL made of nanoparticles in solution, directly on top of the electrode. While heat is still required, the process always stays below 150 degrees C, much lower than the melting point of many plastics.
The new nanoparticles are coated with a layer of chlorine atoms, which helps them bind to the perovskite layer on top — this strong binding allows for efficient extraction of electrons. In a paper recently published in Science ("Efficient and stable solution-processed planar perovskite solar cells via contact passivation"), Tan and his colleagues report the efficiency of solar cells made using the new method at 20.1 per cent.
"This is the best ever reported for low-temperature processing techniques," said Tan. He adds that perovskite solar cells using the older, high-temperature method are only marginally better at 22.1 per cent, and even the best silicon solar cells can only reach 26.3 per cent.
Another advantage is stability. Many perovskite solar cells experience a severe drop in performance after only a few hours, but Tan's cells retained more than 90 per cent of their efficiency even after 500 hours of use. "I think our new technique paves the way toward solving this problem," said Tan, who undertook this work as part of a Rubicon Fellowship.
"The Toronto team's computational studies beautifully explain the role of the newly developed electron-selective layer. The work illustrates the rapidly-advancing contribution that computational materials science is making towards rational, next-generation energy devices," said Professor Alan Aspuru-Guzik, an expert on computational materials science in the Department of Chemistry and Chemical Biology at Harvard University, who was not involved in the work.
"To augment the best silicon solar cells, next-generation thin-film technologies need to be process-compatible with a finished cell. This entails modest processing temperatures such as those in the Toronto group's advance reported in Science," said Professor Luping Yu of the University of Chicago's Department of Chemistry. Yu is an expert on solution-processed solar cells and was not involved in the work.
Keeping cool during the manufacturing process opens up a world of possibilities for applications of perovskite solar cells, from smartphone covers that provide charging capabilities to solar-active tinted windows that offset building energy use. In the nearer term, Tan's technology could be used in tandem with conventional solar cells.
"With our low-temperature process, we could coat our perovskite cells directly on top of silicon without damaging the underlying material," said Tan. "If a hybrid perovskite-silicon cell can push the efficiency up to 30 per cent or higher, it makes solar power a much better economic proposition."
Source: University of Toronto
Leave a comment Posted in Nanotechnology Tagged Genesis Nanotechnology, Perovskites, Solar Cells, Solar energy, Ted Sargent, University of Toronto
Photonic crystals increase solar efficiency: Video: U of Toronto: Dr. Sajeev John
Gains are derived from nanowires and light trapping for better energy conversion.
Sajeev John is a University Professor at the University of Toronto and Government of Canada Research Chair holder. He received his bachelor's degree in physics in 1979 from the Massachusetts Institute of Technology and his PhD in physics at Harvard in 1984. His PhD work introduced the theory of classical wave localization and in particular the localization of light in three-dimensional strongly scattering dielectrics.
Watch the Video Here
His groundbreaking work in the field of light localization that enables light to be controlled at the microscopic level has earned him an international reputation. He is a pioneering theoretician in photonic band gap (PBG) materials. This new class of optical materials presents exciting possibilities in the fields of physics, chemistry, engineering and medicine. PBG materials could eventually be used for optical communications/information processing, clinical medicine, lighting and solar energy harvesting.
John has received numerous awards, including the King Faisal International Prize in Science (2001), the IEEE Nanotechnology Pioneer Award (2008), and the Killam Prize in Natural Sciences (2014) from the Canada Council for the Arts. He is a Fellow of the American Physical Society, OSA, the Royal Society of Canada, and a member of the Max-Planck Society of Germany.
Sajeev John current research (Univ. of Toronto)
Leave a comment Posted in Nanotechnology Tagged Dr. Sajeev John, Nanotechnology, Photonics, Solar energy, University of Toronto
Shape-shifting engineered nanoparticles for delivering cancer drugs to tumours
Professor Warren Chan (IBBME, ChemE, MSE) has spent the last decade figuring out how to deliver chemotherapy drugs into tumours — and nowhere else. Now his lab has designed a set of nanoparticles attached to strands of DNA that can change …more
Chemotherapy isn't supposed to make your hair fall out—it's supposed to kill cancer cells. A new molecular delivery system created at U of T could help ensure that chemotherapy drugs get to their target while minimizing collateral damage.
Many cancer drugs target fast-growing cells. Injected into a patient, they swirl around in the bloodstream acting on fast-growing cells wherever they find them. That includes tumours, but unfortunately also hair follicles, the lining of your digestive system, and your skin.
Professor Warren Chan (IBBME, ChemE, MSE) has spent the last decade figuring out how to deliver chemotherapy drugs into tumours—and nowhere else. Now his lab has designed a set of nanoparticles attached to strands of DNA that can change shape to gain access to diseased tissue.
"Your body is basically a series of compartments," says Chan. "Think of it as a giant house with rooms inside. We're trying to figure out how to get something that's outside, into one specific room. One has to develop a map and a system that can move through the house where each path to the final room may have different restrictions such as height and width."
One thing we know about cancer: no two tumours are identical. Early-stage breast cancer, for example, may react differently to a given treatment than pancreatic cancer, or even breast cancer at a more advanced stage. Which particles can get inside which tumours depends on multiple factors such as the particle's size, shape and surface chemistry.
Chan and his research group have studied how these factors dictate the delivery of small molecules and nanotechnologies to tumours, and have now designed a targeted molecular delivery system that uses modular nanoparticles whose shape, size and chemistry can be altered by the presence of specific DNA sequences.
"We're making shape-changing nanoparticles," says Chan. "They're a series of building blocks, kind of like a LEGO set." The component pieces can be built into many shapes, with binding sites exposed or hidden. They are designed to respond to biological molecules by changing shape, like a key fitting into a lock.
These shape-shifters are made of minuscule chunks of metal with strands of DNA attached to them. Chan envisions that the nanoparticles will float around harmlessly in the blood stream, until a DNA strand binds to a sequence of DNA known to be a marker for cancer. When this happens, the particle changes shape, then carries out its function: it can target the cancer cells, expose a drug molecule to the cancerous cell, tag the cancerous cells with a signal molecule, or whatever task Chan's team has designed the nanoparticle to carry out.
Their work was published this week in two key studies in the Proceedings of the National Academy of Sciences and the leading journal Science.
"We were inspired by the ability of proteins to alter their conformation—they somehow figure out how to alleviate all these delivery issues inside the body," says Chan. "Using this idea, we thought, 'Can we engineer a nanoparticle to function like a protein, but one that can be programmed outside the body with medical capabilities?'"
Applying nanotechnology and materials science to medicine, and particularly to targeted drug delivery, is still a relatively new concept, but one Chan sees as full of promise. The real problem is how to deliver enough of the nanoparticles directly to the cancer to produce an effective treatment.
"Here's how we look at these problems: it's like you're going to Vancouver from Toronto, but no one tells you how to get there, no one gives you a map, or a plane ticket, or a car—that's where we are in this field," he says. "The idea of targeting drugs to tumours is like figuring out how to go to Vancouver. It's a simple concept, but to get there isn't simple if not enough information is provided."
"We've only scratched the surface of how nanotechnology 'delivery' works in the body, so now we're continuing to explore different details of why and how tumours and other organs allow or block certain things from getting in," adds Chan.
He and his group plan to apply the delivery system they've designed toward personalized nanomedicine—further tailoring their particles to deliver drugs to your precise type oftumour, and nowhere else.
Explore further: Cylindrical nanoparticles more deadly to breast cancer
More information: Edward A. Sykes et al. Tailoring nanoparticle designs to target cancer based on tumor pathophysiology, Proceedings of the National Academy of Sciences(2016). DOI: 10.1073/pnas.1521265113
Journal reference: Proceedings of the National Academy of Sciences
Provided by: University of Toronto
Leave a comment Posted in Nanotechnology Tagged Cancer, Cancer Treatment, Nano Medicine, Nano-Bio and Bio-Medicine, Nanotechnology, University of Toronto
QD Solar Brings Quantum Dot – Cell Technology into the Light
Funding from KAUST is helping to bring innovative solar power technology to fruition with startup company QD Solar.
Enabling researchers to take their ideas from the earliest research stages right through to the development and commercialization of a final product is a foundation goal at King Abdullah University of Science and Technology (KAUST). One route is for KAUST to provide active support to startup companies that have strong connections with the university's research activities.
Nicola Bettio, manager of the funding scheme, says seed funding and early-stage capital are made available to startup companies through the KAUST Innovation Fund. "We invest in companies launched by our faculty, researchers and students, alongside international startups that are willing to move their operations to KAUST and Saudi Arabia," Bettio explains. "By encouraging the transition of science into innovation and new ventures we can help to establish a fertile ecosystem for early-stage technology-based companies in Saudi Arabia."
Efficient and cost-effective solar power generation will bring significant economic benefits and drastically reduce the carbon footprint of Saudi Arabia and the rest of the world. For the past several years, KAUST has been supporting research into new technologies using 'colloidal quantum dots' – a potential alternative to the established design of solar cells.
With an ideal design for solar panels the paint made from quantum dots is highly flexible.
© 2015 KAUST
Colloidal quantum dots are tiny semiconductor particles with the capacity to harvest energy from both the visible spectrum and the previously-untapped near-infrared portion of the sun's light. Edward Sargent, a senior researcher at the University of Toronto, has been working on the development and application of colloidal quantum dots for the past ten years, and helped found QD Solar, a Canadian startup company aiming to commercialize the new technology.
"When KAUST was founded back in 2009, there was a very strong emphasis on advancing solar technology that led to the creation of KAUST's Solar and Photovoltaics Engineering Research Center (SPERC)," explains Sargent. "The university employed top professors in the field who have been a key asset during the development of the new quantum dot technique I have been working on. I was fortunate enough to be awarded a KAUST Investigators grant around that time, enabling me to pursue my research in collaboration with these top scientists."
In 2009, Sargent's team at the University of Toronto received a grant from KAUST to advance their research into colloidal quantum dots specifically for solar power applications. Since then, the team's advances have evolved in leaps and bounds. "Our latest design incorporates the dots into a solution, or 'paint', which can be applied to flexible surfaces very easily and cheaply," Sargent explains. "We have also vastly improved the power conversion efficiency of the dots over the past six years, thanks in part to the funding from KAUST."
Sargent and his team, in collaboration with KAUST researchers, are now investigating ways of combining the dots with existing silicon-based solar cells to create new hybrid structure solar panels. This will allow them to harness a far greater fraction of the sun's energy than ever before, improving the panels' efficiency and capacity to generate more power.
Marc Vermeersch, the SPERC managing director, points out that current solar cell technologies are reaching their physical limits. He explains that a key advantage of creating QD Solar's hybrid system is that existing solar panel producers will be able to modify their manufacturing practices relatively easily to incorporate the new design, rather than starting from scratch. Manufacturers will be able to achieve significant economic and efficiency improvements using QD Solar's quantum dot-based solar products, Bettio adds.
KAUST anticipates welcoming a QD Solar presence to Saudi Arabia in the near future, as Bettio explains: "QD Solar is working with the KAUST Innovation Fund to raise capital to establish a significant development facility in our Research & Technology Park. Ultimately, this may lead to the establishment of a Saudi player in the photovoltaic industry and the creation of a hybrid solar panel manufacturing facility in the Kingdom."
1 Comment Posted in Nanotechnology Tagged KAUST, Nano Solar Cells, Nanomaterials, Nanotechnology, QD Solar, Quantum Dots, Ted Sargent, University of Toronto
U of Toronto: "Ghost Busters ~ Nanotechnology ~ Solar Energy" ~ New Inexpensive "Spray-on Solar Cells Turn Any Surface (almost) into a Solar Power Source
"Who Ya Gonna Call?"
Researchers at the University of Toronto have unveiled a cheap, fast spray-on solar cell process that could enable the creation of solar arrays using the most modest of manufacturing methods. Even better, with the cells 'printed' onto flexible material, they could turn anything from airplane wings to your patio furniture into a solar power plant.
The research was led by University of Toronto researcher Illan Kramer, who calls the system sprayLD. Much as with many previous spray-on solar designs, spray LD utilizes colloidal quantum dots (CQD). CQD are tiny, light-sensitive dots—invisible to the naked eye—that can act as an absorbing photovoltaic material. The technology has long held promise, but the process of incorporating light-sensitive CQD's onto surfaces has been expensive, slow and laborious.
What Kramer and his colleagues have done is to invent an entirely new, cheap, efficient technique for creating solar cells using CQD. They based the technique on a newspaper-printing process, and explain "SprayLD blasts a liquid containing CQDs directly onto flexible surfaces, such as film or plastic… by applying ink onto a roll of paper. This roll-to-roll coating method makes incorporating solar cells into existing manufacturing processes much simpler."
As for their prototype, the team admits that it may look "more like junkyard wars than high-tech," but that's because it was made entirely from affordable, readily available parts; U of T explains "[Kramer] sourced a spray nozzle used in steel mills to cool steel with a fine mist of water, and a few regular air brushes from an art store."
Which perhaps makes it all the more surprising that this technique does not appear to cause any major drop offs in efficiency. However, efficiency is still a major consideration with spray-on solar. The sprayLD system converts about 8.1% of sunlight to power, as opposed to 15-20% for standard rooftop solar arrays. But, speaking to Co.Exist, Kramer explained that while he is working on boosting sprayLD's efficiency "we think of ourselves as operating in a slightly different paradigm, where we don't have to be quite as efficient because we're so much less expensive."
And in the long run, Kramer explains: "My dream is that one day you'll have two technicians with Ghostbusters backpacks come to your house and spray your roof!"
Leave a comment Posted in Nanotechnology Tagged Ghost Busters, Nano Solar Cells, Nanomaterials, Nanotechnology, Quantum Dots, Solar Cells, Solar power, University of Toronto
Restoring Order – 'Spintronics' – What is 'Spin-Transport' and Why Does It Matter?
Every electrical device, from a simple lightbulb to the latest microchips, is enabled by the movement of electrical charge, or current. The nascent field of 'spintronics' taps into a different electronic attribute, an intrinsic quantum property known as spin, and may yield devices that operate on the basis of spin-transport.
Atom-optical lattice systems offer a clean, well-controlled way to study the manipulation and movement of spins because researchers can create particle configurations analogous to crystalline order in materials. JQI/CMTC* theorists Xiaopeng Li, Stefan Natu, and Sankar Das Sarma, in collaboration with Arun Paramekanti from the University of Toronto, have been developing a model for what happens when ultracold atomic spins are trapped in an optical lattice structure with a "double-valley" feature, where the repeating unit resembles the letter "W". This new theory result, recently published in the multidisciplinary journal Nature Communications, opens up a novel path for generating what's known as the spin Hall effect, an important example of spin-transport.
Behavior in double-valley lattices has previously been studied for a collection of atoms that all have the same value of spin. In this new work, theorists consider two-component atoms–here, the spin state each atom has can vary between "spin-up" and "spin-down" states.
The spontaneous chiral spin superfluid. When loaded into a hexagonal lattice, chiral spin currents are expected to develop. Here, the orange represents spin-up particles, and green spin-down. Arrows are used to guide the eye along the path of movement. Credit S. Kelley/JQI – See more at: http://jqi.umd.edu/news/restoring-order#sthash.pjtKa0oy.dpuf
Atomic spins in a lattice can be thought of as an array of tiny bar magnets. In the single-component case, the atom-magnets are all oriented the same direction in the lattice. In this case, the magnets can have a tendency to favor only one of the wells of the double-valley. In the two-component system studied here, each atom-magnet can have its' north-pole pointed either up or down, with respect to a particular magnetic field.
Adding this kind of freedom to the model leads to some very curious behavior – the atoms spontaneously separate, with the spin-up atoms collecting into one well of the double-valley, and spin-down atoms in the other. Theorists have dubbed this new state a "spontaneous chiral spin superfluid" (for further explanation of what a superfluid is, see here).
This sort of spin-dependent organization is of great interest to researchers, who could employ it to study the spin Hall effect, analogous to the Hall effect for electrons. Normally, this effect is seen as a result of spin-orbit coupling, or the association of an atom's spin with its motion. In fact, this has long been the approach for producing a spin Hall effect – apply a current to material with spin-orbit coupling, and the spins will gather at the edges according to their orientation.
Ian Spielman's group at the JQI has pioneered laser-based methods for realizing both spin-orbit coupling and the spin Hall effect phenomenon in ultracold atomic gases. In contrast, for the superfluid studied here, spin-sorting is not the result of an applied field or asymmetric feature of the system, but rather emerges spontaneously. It turns out this behavior is driven by tiny, random quantum fluctuations, in a paradoxical phenomenon known as quantum order by disorder.
Quantum order by disorder
Generally speaking, the transition from disorder to order is a familiar one. Consider water condensing into ice: this is a disordered system, a liquid, transitioning to a more ordered one, a solid. This phase transformation happens because the molecules become limited in their degrees of freedom, or the ability to move in different ways. Conversely, adding noise to a system, such as heating an ice cube, generally leads to a more disordered state, a pool of water. Amazingly, noise or fluctuations in a system can sometimes drive a system into a more ordered state.
The theory team showed that this is indeed the case for certain kinds of atoms loaded into a double-valley optical lattice. While this system is a quiet, mostly non-thermal environment, noise still lurks in the form of quantum mechanical fluctuations. In this system, the spin-up and spin-down atoms can potentially be configured in four different, but energetically identical arrangements. This is known as degeneracy and can be indicative of the amount of order in a system–the more equal energy states, the more disordered a system. It turns out that these arrangements have different amounts of quantum noise and these fluctuations play a crucial role. Surprisingly, the quantum fluctuations will break up the degeneracy, thus restoring order.
What's the upshot? In this system, the resulting lowest energy configuration–a chiral spin superfluid– is preferred independent of the type of double-valley lattice geometry, indicating a type of universal behavior. With this in mind, the theorists examine a number of lattice structures where this phenomenon might be realized. For instance, if the fluid is placed into a hexagonal lattice configuration, similar to the structure of graphene, they expect the characteristic spin currents of the spin Hall effect to emerge, as depicted in the graphic, above.
In the publication, the team points out that optical lattice systems are a flexible, pristine platform for examining the effect of these tiny variations in quantum fluctuations, which are often masked in real materials. Outside of exploring novel forms of matter like the one found here, research into spin and atom manipulation has applications in emerging electronic-like technologies, such as spintronics, valleytronics and atomtronics.
*JQI (Joint Quantum Institute) and CMTC (Condensed Matter Theory Center)
This news item was written by S. Kelley, JQI.
– See more at: http://jqi.umd.edu/news/restoring-order#sthash.pjtKa0oy.dpuf
Leave a comment Posted in Nanotechnology Tagged Canada, Commercialization, JQI, Nanoparticle, Nanotechnology, Spintronics, University of Toronto
Finding the 'Holy Grail' for Solar Energy "Are We (almost) There Yet?"
*** "Throw-Back Thursdays" – Maybe not so much! Today's Post(s) are a compilation of some of 2014's LATEST advances in making Solar Renewable Energy an Affordable, Efficient and Commercially Viable Energy Source.Quote, "Solar-cell technology has advanced rapidly, as hundreds of groups around the world pursue more than two dozen approaches using different materials, technologies, and approaches to improve efficiency and reduce costs."
Universities and Organizations such as the University of California, University of Sheffield, University of Electro-Communications, Okinawa Institute of Science and Technology Graduate University, MIT, University of Toronto, NREL, NIST, NRL … ALL are seeking new discoveries, new methods of application-processes … to achieve the actualization and implementation of "Abundant, Cheap, Renewable Energy". In this Compilation:
Singlet Fission – For Increased Efficiencies – 2014-07
Spray-On Solar Cells – 2014-08
Pervoskites – A New (LOW COST) Semiconductor Material for Solar Cells – 2014-09
'Dark' Spin-Triplet Excitons – 2014-10
Self-Organized Indium Arsenide Quantum Dots for Solar Cells – 2014-09
A New Breed of "Quantum Dot" Solar Cells – 2014-05
Solar Energy Boost: 'Singlet Fission' Could Increase Efficiency by as much as 30%
A perspective article published last month by University of California, Riverside chemists in the Journal of Physical Chemistry Letters was selected as an Editors Choice—an honor only a handful of research papers receive. The perspective reviews the chemists' work on "singlet fission," a process in which a single photon generates a pair of excited states. This 1->2 conversion process, as it is known, has the potential to boost solar cell efficiency by as much as 30 percent.
Applications of the research include more energy-efficient lighting and photodetectors with 200 percent efficiency that can be used for night vision. Biology may use singlet fission to deal with high-energy solar photons without generating excess heat, as a protective mechanism.
Currently, solar cells work by absorbing a photon, which generates an exciton, which subsequently separates into an electron-hole pair. It is these electrons that become solar electricity. The efficiency of these solar cells is limited to about 32 percent, however, by what is called the "Shockley-Queisser Limit." Future solar cells, also known as "Third Generation" solar cells, will have to surpass this limit while remaining inexpensive, requiring the use of new physical processes. Singlet fission is an example of such a process.
"Our research got its launch about ten years ago when we started thinking about solar energy and what new types of photophysics this might require," said Christopher Bardeen, a professor of chemistry, whose lab led the research. "Global warming concerns and energy security have made solar energy conversion an important subject from society's point-of-view. More efficient solar cells would lead to wider use of this clean energy source."
When a photon is absorbed, its energy takes the form of an exciton inside the material. Bardeen explained that excitons come in two "flavors," defined by the electron spins in them. One flavor is singlet, where all spins are paired. The other flavor is triplet, where two electrons are unpaired. In organic semiconductors, these two types of excitons have different energies.
"If a triplet exciton has half the energy of a singlet, then it is possible for one singlet exciton, generated by one photon, to split into two triplet excitons," Bardeen said. "Thus, you could have a 200 percent yield of excitons—and hopefully, electrons—per absorbed photon."
He explained that the Shockley-Queisser Limit involves photon absorption to create an exciton, which is basically a bound electron (- charge) and hole (+ charge) pair. In order to get useful electron flow (photocurrent), these excitons must be dissociated. Ideally, one exciton produces one electron (hole) and thus current to run, say, a light bulb.
"To absorb a photon, the photon energy has to be greater than the bandgap of the semiconductor, so you already miss part of the solar spectrum," Bardeen said. "But if you absorb a photon with energy higher than the bandgap, it has too much energy, and that excess energy is usually wasted as heat. The trick is to take that high energy exciton and split the energy into two excitons, rather than dissipating it as heat."
Bardeen explained that the singlet exciton spontaneously splits into the two triplets, through a mechanism that is still under active investigation.
"The exact mechanism is unknown, but it does happen quickly—at the sub-nanosecond timescale—and with high efficiency," he said. "Our work has shown that it is very sensitive to the alignment and position of the two molecules—at least two are required, since we have two excitons—involved in singlet fission. Recent work at MIT has already demonstrated an organic photovoltaic cell with more than 100 percent external quantum efficiency based on this effect. It may be possible to integrate this effect with inorganic semiconductors and use it to raise their efficiencies."
Next, Bardeen's lab will look for new materials that exhibit singlet fission, figure out how to take the triplet excitons and turn them into photocurrent efficiently, and look at how the spin properties of the electrons affect the exciton dynamics.
Explore further: Two for one in solar power
A team of scientists at the University of Sheffield are the first to fabricate perovskite solar cells using a spray-painting process – a discovery that could help cut the cost of solar electricity.
A robot spray-coating glass with the polymer to create a solar cell. The technology could one day be used on glass in buildings and cars. For more information about our solar cell research visit http://www.sheffield.ac.uk/physics
Experts from the University's Department of Physics and Astronomy and Department of Chemical and Biological Engineering have previously used the spray-painting method to produce solar cells using organic semiconductors – but using perovskite is a major step forward.
Efficient organometal halide perovskite based photovoltaics were first demonstrated in 2012. They are now a very promising new material for solar cells as they combine high efficiency with low materials costs.
The spray-painting process wastes very little of the perovskite material and can be scaled to high volume manufacturing – similar to applying paint to cars and graphic printing.
Lead researcher Professor David Lidzey said: "There is a lot of excitement around perovskite based photovoltaics.
"Remarkably, this class of material offers the potential to combine the high performance of mature solar cell technologies with the low embedded energy costs of production of organic photovoltaics."
While most solar cells are manufactured using energy intensive materials like silicon, perovskites, by comparison, requires much less energy to make. By spray-painting the perovskite layer in air the team hope the overall energy used to make a solar cell can be reduced further.
Professor Lidzey said: "The best certified efficiencies from organic solar cells are around 10 per cent. "Perovskite cells now have efficiencies of up to 19 per cent. This is not so far behind that of silicon at 25 per cent – the material that dominates the world-wide solar market."
He added: "The perovskite devices we have created still use similar structures to organic cells. What we have done is replace the key light absorbing layer – the organic layer – with a spray-painted perovskite. "Using a perovskite absorber instead of an organic absorber gives a significant boost in terms of efficiency."
The Sheffield team found that by spray-painting the perovskite they could make prototype solar cells with efficiency of up to 11 per cent.
Professor Lidzey said: "This study advances existing work where the perovskite layer has been deposited from solution using laboratory scale techniques. It's a significant step towards efficient, low-cost solar cell devices made using high volume roll-to-roll processing methods."
Solar power is becoming an increasingly important component of the world-wide renewables energy market and continues to grow at a remarkable rate despite the difficult economic environment.
Professor Lidzey said: "I believe that new thin-film photovoltaic technologies are going to have an important role to play in driving the uptake of solar-energy, and that perovskite based cells are emerging as likely thin-film candidates. "
Explore further: A new stable and cost-cutting type of perovskite solar cell
New "Dirt Cheap" Solar Cells
One of the most common complaints about solar power is solar panels are still too expensive to be worth the investment. Many researchers have responded by making solar cells, the tile-like components of solar panels that absorb and transfer energy, more efficient and longer lasting. But even the longest living solar cells that most effectively convert sunlight to energy will not become common if they are prohibitively expensive.
Therefore, Professor Yabing Qi, the head of the Energy Materials and Surface Sciences Unit at the Okinawa Institute of Science and Technology Graduate University, has a different idea: make solar cells using a type of semiconductor called perovskite materials, which are, in Qi's words, "dirt cheap." If solar cells are cheap enough, Qi reasons that people will want to use them for the immediate payback in energy savings.
Now Professor Qi and members of his research unit have developed a new method for making perovskite solar cells worthy of attention, and The Royal Society of Chemistry published their findings September 5, 2014 in their journal, Energy & Environmental Science.
Qi's new method uses what he calls hybrid deposition to create perovskite solar cells, made from a mixture of inexpensive organic and inorganic raw materials. In addition, his solar cell is about a thousand times thinner than a silicon solar cell, and therefore uses far less material.
Qi estimates that for the same price, he could either buy raw materials to build 1000 square meters of his solar cell, or he could buy about 20 wafers of crystallized silicon, to build 0.16 square meters of traditional solar panels. "Silicon is not rare," Qi explains, "but processing silicon requires expensive equipment and sophisticated steps demanding high temperature, vacuum, or high pressure, and that makes crystallized silicon very expensive."
In contrast, the hybrid deposition process uses less energy to produce a solar cell at a far lower temperature. In fact, Qi envisions manufacturing the new solar cells using a low-cost printing process. The process would deposit the materials onto thin sheets of PET plastic very quickly to make large quantities of cheap solar cells. Qi does not yet know the limits of his hybrid cells, but optimists in his field hope that they could reach 20% efficiency. This means that that the solar cells will convert 20% of the energy they absorb from the sun into usable energy, which is comparable to the best silicon solar panels on the market.
The extremely thin perovskite cell that Qi and his lab designed measures merely 135 nanometers and reaches an efficiency of 9.9%. Because these films are semitransparent, Qi hopes to use them on windows, as a sort of lightweight set of blinds. "It will be a window and at the same time it will be a solar cell," he says. "Some of the light could go through and the rest will be absorbed. Then, a certain percentage of the absorbed light will be converted to electricity."
If solar cells are cheap enough, consumers will reap almost immediate benefits even if the solar cells are not the most efficient, because their savings on air conditioning and electricity will offset the expense. "If it's so cheap that it is like wallpaper, then you might as well use it," said Qi. "It's like a free gift. It's an investment with a lot of payback."
Explore further: Researchers use liquid inks to create better solar cells
Hybrid Materials could Smash the Solar Efficiency Ceiling
A new method for transferring energy from organic to inorganic semiconductors could boost the efficiency of widely used inorganic solar cells.
Researchers have developed a new method for harvesting the energy carried by particles known as 'dark' spin-triplet excitons with close to 100% efficiency, clearing the way for hybrid solar cells which could far surpass current efficiency limits.
The team, from the University of Cambridge, have successfully harvested the energy of triplet excitons, an excited electron state whose energy in harvested in solar cells, and transferred it from organic to inorganic semiconductors. To date, this type of energy transfer had only been shown for spin-singlet excitons. The results are published in the journal Nature Materials.
In the natural world, excitons are a key part of photosynthesis: light photons are absorbed by pigments and generate excitons, which then carry the associated energy throughout the plant. The same process is at work in a solar cell.
In conventional semiconductors such as silicon, when one photon is absorbed it leads to the formation of one free electron that can be extracted as current. However, in pentacene, a type of organic semiconductor, the absorption of a photon leads to the formation of two electrons. But these electrons are not free and they are difficult to pin down, as they are bound up within 'dark' triplet exciton states.
Excitons come in two 'flavours': spin-singlet and spin-triplet. Spin-singlet excitons are 'bright' and their energy is relatively straightforward to harvest in solar cells. Triplet-spin excitons, in contrast, are 'dark', and the way in which the electrons spin makes it difficult to harvest the energy they carry.
"The key to making a better solar cell is to be able to extract the electrons from these dark triplet excitons," said Maxim Tabachnyk of the University's Cavendish Laboratory, the paper's lead author. "If we can combine materials like pentacene with conventional semiconductors like silicon, it would allow us to break through the fundamental ceiling on the efficiency of solar cells."
Using state-of-art femtosecond laser spectroscopy techniques, the team discovered that triplet excitons could be transferred directly into inorganic semiconductors, with a transfer efficiency of more than 95%. Once transferred to the inorganic material, the electrons from the triplets can be easily extracted.
"Combining the advantages of organic semiconductors, which are low cost and easily processable, with highly efficient inorganic semiconductors, could enable us to further push the efficiency of inorganic solar cells, like those made of silicon," said Dr Akshay Rao, who lead the team behind the work.
The team is now investigating how the discovered energy transfer of spin-triplet excitons can be extended to other organic/inorganic systems and are developing a cheap organic coating that could be used to boost the power conversion efficiency of silicon solar cells.
Self-Organized Indium Arsenide Quantum Dots for Solar Cells
Kouichi Yamaguchi is internationally recognized for his pioneering research on the fabrication and applications of 'semiconducting quantum dots' (QDs). "We exploit the 'self-organization' of semiconducting nanocrystals by the 'Stranski-Krasnov (SK) mode of crystal growth for producing ordered, highly dense, and highly uniform quantum dots," explains Yamaguchi. "Our 'bottom-up' approach yields much better results than the conventional photolithographic or 'top-down' methods widely used for the fabrication of nano-structures."
Notably, electrons in quantum dot structures are confined inside nanometer sized three dimension boxes. Novel applications of 'quantum dots'—including lasers, biological markers, qubits for quantum computing, and photovoltaic devices—arise from the unique opto-electronic properties of the QDs when irradiated with light or under external electromagnetic fields.
"Our main interest in QDs is for the fabrication of high efficiency solar cells," says Yamaguchi. "Step by step we have pushed the limits of 'self-organization' based growth of QDs and succeeded in producing highly ordered, ultra-high densities of QDs."
The realization of an unprecedented QDs density of 5 x 1011 cm-2 in 2011 was one of the major milestones in the development of 'self-organization' based semiconducting QDs for solar cells by Yamaguchi and his colleagues at the University of Electro-Communications (UEC). "This density was one of the critical advances for achieving high efficiency quantum dot based photo-voltaic devices," says Yamaguchi.
Specifically, Yamaguchi and his group used molecular beam epitaxy (MBE) to grow a layer of InAs QDs with a density of 5 x 1011 cm-2 on GaAsSb/GaAs (100) substrates. Importantly, the breakthrough that yielded this high density of highly ordered QDs was the discovery that InAs growth at a relatively low substrate temperature of 470 degrees Celsius on Sb-irradiated GaAs layers suppressed coalescence or 'ripening' of InAs QDs that was observed at higher temperatures. Thus the combination of the Sb surfactant effect and lower growth temperature yielded InAs QDs with an average height of 2.02.5 nm.
InAs QD density: 1.0×1012 cm-2
The potential for photovoltaic device applications was examined by sandwiching a single layer of InAs QDs in a pin-GaAs cell structure. The resulting external quantum efficiency of these solar cell structures in the 900 to 1150 nm wavelength range was higher than devices with the QD layer.
"Theoretical studies suggest QDs solar cells could yield conversion efficiencies over 50%," explains Yamaguchi. "This is a very challenging target but we hope that our innovative approach will be an effective means of producing such QD based high performance solar cells. We have recently achieved InAs QDs with a density of 1 x 1012 cm-2."
Variation of power conversion efficiency with quantum dot density (calculated results). Enlarge
Quantum Dot Photovoltaics: A New Breed of Solar Cells: Setting New Records for Efficiency
Solar-cell technology has advanced rapidly, as hundreds of groups around the world pursue more than two dozen approaches using different materials, technologies, and approaches to improve efficiency and reduce costs.
Now a team at MIT has set a new record for the most efficient quantum-dot cells—a type of solar cell that is seen as especially promising because of its inherently low cost, versatility, and light weight.
While the overall efficiency of this cell is still low compared to other types—about 9 percent of the energy of sunlight is converted to electricity—the rate of improvement of this technology is one of the most rapid seen for a solar technology. The development is described in a paper, published in the journal Nature Materials, by MIT professors Moungi Bawendi and Vladimir Bulović and graduate students Chia-Hao Chuang and Patrick Brown.
The new process is an extension of work by Bawendi, the Lester Wolfe Professor of Chemistry, to produce quantum dots with precisely controllable characteristics—and as uniform thin coatings that can be applied to other materials. These minuscule particles are very effective at turning light into electricity, and vice versa. Since the first progress toward the use of quantum dots to make solar cells, Bawendi says, "The community, in the last few years, has started to understand better how these cells operate, and what the limitations are."
The new work represents a significant leap in overcoming those limitations, increasing the current flow in the cells and thus boosting their overall efficiency in converting sunlight into electricity.
Many approaches to creating low-cost, large-area flexible and lightweight solar cells suffer from serious limitations—such as short operating lifetimes when exposed to air, or the need for high temperatures and vacuum chambers during production.
By contrast, the new process does not require an inert atmosphere or high temperatures to grow the active device layers, and the resulting cells show no degradation after more than five months of storage in air.
Bulović, the Fariborz Maseeh Professor of Emerging Technology and associate dean for innovation in MIT's School of Engineering, explains that thin coatings of quantum dots "allow them to do what they do as individuals—to absorb light very well—but also work as a group, to transport charges." This allows those charges to be collected at the edge of the film, where they can be harnessed to provide an electric current.
The new work brings together developments from several fields to push the technology to unprecedented efficiency for a quantum-dot based system: The paper's four co-authors come from MIT's departments of physics, chemistry, materials science and engineering, and electrical engineering and computer science. The solar cell produced by the team has now been added to the National Renewable Energy Laboratories' listing of record-high efficiencies for each kind of solar-cell technology.
The overall efficiency of the cell is still lower than for most other types of solar cells. But Bulović points out, "Silicon had six decades to get where it is today, and even silicon hasn't reached the theoretical limit yet. You can't hope to have an entirely new technology beat an incumbent in just four years of development." And the new technology has important advantages, notably a manufacturing process that is far less energy-intensive than other types.
Chuang adds, "Every part of the cell, except the electrodes for now, can be deposited at room temperature, in air, out of solution. It's really unprecedented."
The system is so new that it also has potential as a tool for basic research. "There's a lot to learn about why it is so stable. There's a lot more to be done, to use it as a testbed for physics, to see why the results are sometimes better than we expect," Bulović says.
A companion paper, written by three members of the same team along with MIT's Jeffrey Grossman, the Carl Richard Soderberg Associate Professor of Power Engineering, and three others, appears this month in the journal ACS Nano, explaining in greater detail the science behind the strategy employed to reach this efficiency breakthrough.
The new work represents a turnaround for Bawendi, who had spent much of his career working with quantum dots. "I was somewhat of a skeptic four years ago," he says. But his team's research since then has clearly demonstrated quantum dots' potential in solar cells, he adds.
Arthur Nozik, a research professor in chemistry at the University of Colorado who was not involved in this research, says, "This result represents a significant advance for the applications of quantum-dot films and the technology of low-temperature, solution-processed, quantum-dot photovoltaic cells. … There is still a long way to go before quantum-dot solar cells are commercially viable, but this latest development is a nice step toward this ultimate goal."
2 Comments Posted in Nanotechnology Tagged Nano Solar Cells, Nanomaterials, Nanotechnology, NIST, NREL, Solar cell, Solar energy, Solar power, United States Department of Energy, University of Toronto
The "Great Race" to Capture 'Cheap-Efficient' Solar Energy – Are the Answers at the University of Toronto & KAUST?
The global race to harvest the sun's energy has researchers all over the world competing to develop the new technologies that they hope will end our reliance on fossil fuels.
One of the latest announcements is from a team at Michigan State University that's developed a clear pane of plastic that could be used on windows to capture sunlight. ScienceDaily, an online publication of research news, reports that the luminescent solar concentrator, as it's called, has the potential to revolutionize commercial or industrial window design by turning windows into large-scale collectors of solar energy.
But even while science writers enthusiastically describe the promise of this latest solar technology, researchers immersed in the field tend to greet the news more cautiously.
Professor Ted Sargent, a leader internationally in the development of "paintable" solar cells, which has spawned related research around the world, says "what's clearly different and clearly interesting" is that the Michigan team's work allows them to take a significant part of the sun's rainbow spectrum, convert it into a single colour and "put it off to the edges" of the plastic pane.
Professor Sargent's lab members, Zhijun Ning and Oleksandr Vozny, examining a new paint-on solar chip. (Ted Sargent/University of Toronto)
'If this development can go all the way," says Sargent, it offers the possibility of yet another venue for deploying solar cells. Instead of just putting solar panels on the roof of a house, says Sargent, these transparent cells could be placed on windows and windshields.
But Sargent says that in the search for the solar technology breakthrough that will transform the world, "this one's not there yet."
"They kind of get the light ready in an appealing way," says Sargent. Problem is, the mostly transparent material is "nice for a window, but solar cells have to absorb light, so it's not good for collecting light."
The paint-on solar chip, about the size of a postage stamp. (Ted Sargent/University of Toronto )
Many new developments in the solar field are plagued by those kinds of trade-offs — between cost of production and efficiency. In the case of a luminescent solar concentrator for windows, Sargent says if it can be manufactured cheaply enough it has the potential for wide-spread application by turning windows and window walls around the world into solar harvestors, but at the cost of inefficiently capturing the full potential of the sun's energy.
Sargent's own work in nanotechnology led to an ink-based solar cell — essentially suspending the ingredients of solar cells in liquid that could be "painted' onto any surface.
In a Tedx Toronto talk, Sargent describes the incredible potential of solar energy: "Every hour enough energy reaches the earth from the sun to power the earth for an entire year."
It's all about the technology," says Sargent. "Cheap and efficient is the holy grail."
Led by Sargent, a researchers at U of T are re-imagining the solar cell. Conventional cells use silicon, "a beautiful semi-conductor material", limited by what Sargent calls "a quality of rigid perfection," accompanied by equally rigid costs associated with the manufacturing process and installation.
Sargent's team has developed a solar cell that he says is more akin to printing a newspaper – a semi-conductor ink printed onto a flexible backing. Unlike silicon-based cells, in this application solar cells are painted on a light-weight flexible carpet that can be spread out on a roof, a road or any other surface exposed to the sun.
"You can literally paint surfaces with this ink" – a cheap way to make a solar cell, says Sargent. "And it's very black – the perfect absorber of visible light and of infrared light."
Solar conference coming
Ted Sargent is hosting a conference in Toronto next October with world leaders in solar technologies. There will be a public lecture by Connaught Symposium guest of honour Professor Sir Richard Friend (Cambridge University) on Wednesday, October 8, 2014 at 8 p.m. at the Royal Conservatory of Music. It is open to all, with $10 tickets going on sale on September 3. Professor Sir Richard Friend is the world's most renowned scholar in the field of energy harvesting. See more here.
"This group of researchers has come together around the idea that nature offers us ideas and inspirations to develop cost-effective solar technologies. It's such an important topic for scientists, politicians and public and it impacts the future of our planet," said Sargent.
"Sir Richard Friend is one of the leading researchers. He's also a truly engaging speaker from Cambridge who can speak to the big picture about what we can learn from nature and potential for solar-energy harvesting."
That capacity to absorb infrared light is especially powerful because the spectrum includes as much infrared as visible light. But, says Sargent, the infrared portion of the sun's spectrum is often ignored And yet, when the sun beats down on our face, much of the heat we feel is infrared light.
Sargent's group led the world in making most efficient solar cells in the world based on ink-based colloidal quantum dots. A finished solar cell — about the size of a postage stamp – has the ability to both absorb the sun's energy and to extract it as electricity.
In an interview with Metro Morning's Matt Galloway, Sargent said that at this point, the technological breakthrough that will revolutionize the world's energy production is "years, not decades away.
But it will require teams of researchers working in many different disciplines to get there, "from chemistry to physics to material science."
In Sargent's case, It's led to a collaboration with Saudi Arabia's KAUST (King Abdullah University of Science and Technology), a new but well-funded university that has made the development of cheap, efficient solar energy one of its main research goals.
The collaboration carries intriguing strategic possibilities.
Ted Sargent is a professor at University of Toronto. (Ted Sargent/University of Toronto)
Historically, Saudi Arabia's major export is fossil fuels but in the future, says Sargent, Saudi Arabia intends to be a world leader in exporting technology associated with solar energy.
It's supported by that other natural resource that Saudi Arabia has in such abundance — sunshine.
And nature itself is teaching researchers to think differently. In the international race to develop cheap, efficient solar technology, Sargent is increasingly turning to nature to learn its processes.
"It's remarkable what nature does," says Sargent. "It's the epitome of 'efficient-enough' solar capture. How much does it cost for grass to grow or for a leaf to grow on a tree? Nature has its own systems."
Sargent speaks with the kind of respect that can only come from a lifetime of trying to crack one of the world's most urgent environmental challenges. Nature, says Sargent, proves that it's possible to cover the earth with solar harvestors. "It's an inspiration and challenge to researchers to do the same."
1 Comment Posted in Nanotechnology Tagged KAUST, Nano Solar Cells, Nanomaterials, Nanotechnology, Saudi Arabia, Solar Cells, Solar energy, University of Toronto
"Nano Assembly" Looks to Change the Future … And the Costs of Quantum Dot Manufacturing
*** "Great Things from Small Things" has written and re-published many articles over the past several years on the "wee tiny" nano-materials called Quantum Dots. Their enabling applications across a broad spectrum of Markets & Industries from Electronics, Textiles, Drug Therapies, Bio-Medicines to Solar Energy Generation/ Storage and Display Screens, has been well documented. It would seem these new "wonder nano-materials" are poised to change the entire landscape of how we innovate and manufacture almost everything.
So what's the catch? What has delayed a broader acceptance and integration of quantum dots into the marketplace? It would seem the answer lies not in the efficacy & validity of the new 'nano-materials' but more in the age old and time tested axiom of: "Low Cost + High Consistency + Ability to Mass Scale = Commercial Success.
A new company Nano Assembly has plans to change all that. Business Investigative writer Osama Natto highlights the High Profile Team and award winning company's collaboration with KAUST (King Abdullah University of Science and Technology) to integrate these disruptive game changing materials in the broader marketplace for commercial success.
Article by Osama Natto
Quantum dots are expensive enough to limit their otherwise broad applicability.
The standard way to make these semiconductor particles is to heat a solution to a high temperature in a small flask and inject a special agent. However, the solution will cool down naturally, and manual operation cannot maintain the high temperature needed for efficient production.
One can scale production of quantum dots up by using a larger flask, but this does not produce quality results. One can also use a continuous-flow reactor to benefit from higher consistency and automatic operation, as well as production of quantum dots in different sizes, but this still does not produce high-quality quantum dots.
The Nano Assembly team has found a new method for producing quantum dots consistently and at a significantly lower price than competitors.
How the Product Works
The optical and electrical properties of quantum dots depend on their size and type. Different sizes emit different colors and exhibit a different absorption spectrum. Quantum dots must be produced according to careful standards.
The Technology Nano Assembly's dual-stage servo control method allows the production of quantum dots without the broad peaks and troughs that come from other methods. The lower the absorption peak, the higher the quality of the quantum dots.
Where It Fits into the Market The quantum dots produced by Nano Assembly can be used anywhere that more expensively-produced quantum dots are utilized, allowing competing offerings to be replaced.
Patent Status The team has already filed for a patent and published their work in a high-impact journal.
Benefits to Saudi Economy These "low-cost and high quality quantum dots" could allow tech products already popular in Saudi Arabia, such as mobile phones, to include more efficient displays while remaining inexpensive. The team's affordable quantum dots could also allow more people access to high-quality medical imaging, and improve solar cell technology to allow effective harvest of one of Saudi Arabia's greatest natural resources: sunlight.
In part due to their ability to produce a rainbow of bright colors efficiently, quantum dots are used in display technologies. Since quantum dots are so tiny, they can also move anywhere in the human body, making them useful in the field of medical imaging as replacements for fluorescence-based biosensors that use organic dyes. Quantum dots can also be used as the absorbing photovoltaic material in solar cells.
Features and Benefits of the Product
High quality relative to competitors' quantum dots
Low cost relative to competitors' quantum dots
Since quantum dots are used to make other products, Nano Assembly would be operating in the business-to-business market, although applications in fields like solar power also leave the door open for business-to-government sales.
Current methods for producing quantum dots include high-temperature dual injection synthesis, molecular seeding, and a variation of the high-temperature dual injection method that incorporates a continuous flow system.
(Image courtesy of King Abdullah University of Science and Technology)
Names and Profiles of Team Members
Jun Pan
Ala'a El-Ballouli
Osman Bakr
Edward Sargent
Credentials Dr. Pan has earned both a Bachelor of Science and Master of Science from Anhui Polytechnic University, along with a Ph.D. in Chemistry from the University of Science and Technology of China. He is now participating in a post-doctoral fellowship at KAUST. Within the Nano Assembly team, Dr. Pan is in charge of production.
El-Ballouli holds a Bachelor of Science in Chemistry and a Master of Science in Organic Chemistry from the American University of Beirut. She is currently a Ph.D. student at KAUST. Her primary area of interest is continuous-flow synthesis and size separation of quantum dots for assembly in solar cells. El-Ballouli is in charge of product testing for the team.
Dr. Bakr has earned a Bachelor of Science in Materials Science and Engineering from the Massachusetts Institute of Technology (MIT), as well as both a Master of Science and Ph.D. in Applied Physics from Harvard University. He is currently an Assistant Professor of Materials Science and Engineering, and Principal Investigator at KAUST. Dr. Bakr acts as scientific adviser to the Nano Assembly team.
Dr. Sargent holds a Bachelor of Science in Engineering Physics from Queen's University, along with a Ph.D. in Electrical and Computer Engineering (Photonics) from the University of Toronto. He is the Vice Dean of Research for the Faculty of Applied Science & Engineering, a Professor in the Department of Electrical & Computer Engineering (ECE), and a KAUST Investigator. Dr. Sargent is the technique and business adviser for the team.
Nano Assembly has already begun the process of incorporating their company. Their immediate task is to set up the production line that they have prepared, test it, and scale it up. They are expecting significant annual growth through 2017.
Big-Picture Impact on the Saudi Economy
The availability of high-quality quantum dots at a low price could help more tech-savvy companies and entrepreneurs enter the electronics, solar power, and medical imaging fields, among others. It could also help existing companies produce more cost-effective offerings within these fields. Either way, the end result would be a more technologically advanced and competitive Saudi Arabia.
Leave a comment Posted in Nanotechnology Tagged breakthrough discovery, Carbon Nanotubes, Display Screens, Dr. Ted Sargent, Fuel Cells, KAUST, King Abdullah University of Science and Technology, Nano Batteries, Nano Drug Therapies, Nano Medicine, Nano-Bio and Bio-Medicine, Nanomaterials, Nanotechnology, Printed Electronics, Quantum dot, Renewable Energy, Science, Solar Cells, University of Toronto


text:
Skin Cleansing Products
What does pH-Balanced mean?
by Susan Sentry
You can use pH-Paper or litmus paper to find out the pH of your cleansers.
©iStockphoto.com/Sabine Kappel
If you think back to high school chemistry class, you may recall that pH is an abbreviation for potential hydrogen. A pH number measures from 0 to14 how acidic or alkaline a liquid is -- anything above 7 is alkaline and anything below 7 is acid. Water has a pH level of 7 -- it's neutral, meaning it has the same amount of acids and alkalis, which balance each other out.
When you're thinking about liquids in terms of their pH levels, going up or down one number on the scale represents a tenfold change in the acidity or alkaline nature of a liquid. For example, the pH level of milk is around 6. Because the pH level of water is 7, milk is 10 times more acidic than water. Vinegar has a pH of about 3, making it 40 times more acidic than water [source: Carpi].
On the other end of the spectrum, milk of magnesia is a base with a pH of 10, which is why it's soothing to an acidic stomach. Lye has a pH of 13 and can dissolve sticky substances like fat. As you can see, substances at either end of the pH spectrum can be corrosive -- but if you combine these substances, they neutralize and create salt water. They balance because they're at opposite ends of the scale [source: Ophardt].
Now that you've had your general chemistry lesson, take a look at the next page to learn what pH-balanced means for your skin cleanser.
Is a daily shower too much for your skin?
How to Wash Your Face

redpajama_set_name: RedPajamaCommonCrawl


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Star Trek: Discovery 1×9 Review: Into the Forest I Go
Posted by Angel Wilson On November 16, 2017 0 Comment
The finale for the first half of Star Trek: Discovery season 1, "Into the Forest I Go", was both action-packed and heart-wrenching.
I am immensely pleased that a large portion of the show is focusing on Stamets. "Into the Forest I Go" was largely about the damage being done to him as the catalyst for the spore drive. It's been taking it's toll on him with each jump. When he looked at Culber before one of the jumps and said "I love you", I clutched my chest in pain. He didn't even seem confident that he'd make it through that jump, let alone the dozens that lay ahead. The episode even ended on a cliffhanger about his safety, which signals to me that his status as a crucial part of the show is fairly solid. I hope that the DSC writers are aware of and know to avoid the Bury Your Gays trope.
Stamets, though initially introduced as a blunt and somewhat cold officer, has quickly become the heart of the show. And yeah, okay, I may be slightly biased because of the fact that it's Anthony Rapp and the character is gay. But regardless, his fear induced sentimentality this episode hit all the right notes for me.
Bonus points: we got the first same sex kiss by a same sex couple in the Star Trek franchise,
While Stamets was the heart of "Into the Forest I Go," the conflict with the Klingons was the action. The Ash-is-Voq conspiracy theory isn't showing any sign of slowing. The portrayal of his PTSD was realistic and heartbreaking, but many of the scenes in his flashbacks were questionable. We saw him being cut into. We saw a Klingon screaming and a quick cut to his face screaming. What are we supposed to think here? Maybe I'm blinded by the conspiracy at this point. But at the same time the Mr Robot and Westworld conspiracies turned out to be true, so there's no harm believing it I guess.
This was the final episode until January and we're left on a massive cliffhanger. During Stamets' final jump there was a malfunction, and Discovery is now trapped in uncharted space.
Author: Angel Wilson
Angel is the admin of The Geekiary and a geek culture commentator. She earned a BA in Film & Digital Media from UC Santa Cruz. She's contributed to various podcasts and webcasts including An Englishman in San Diego, Free to Be Radio, and Genre TV for All. She's written for Friends of Comic Con and is a 2019 Hugo Award winner for contributing fanfic on AO3. She identifies as queer.
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When I set out to do a one-sheet for my album, i didn't really know what it should look like. There are countless 'tutorials' out there, but what I really wanted was an example of an actual one sheet.
Unlike many of the other tutorials, I'll show you the one sheet I used, explain the reasoning for it's layout and link to anything that may be useful. I'll also not ask for any money, unlike those other tutorials that I won't stoop to name.
I used Word to do my press release but you'd have a better time with a program like Adobe InDesign.
The product I was writing about was my solo album The Melody Of Distaste.
Now I was fortunate enough to have a few patient and kind friends who had seen one sheets before, and thanks to their advice, I was able to pull a pretty good press release together.
The most important thing I learned along the way was that basically, you want to tell the reader what you want them to write.
In the busy world of journalism, no one wants to fish about for information. Have a good, clear header that not only sums up the release but can also be used as a direct sound byte that they can use, should they wish to do so.
More often than not, you will see your own words being directly used to describe your own product – so make it a good tagline!
As you can see, I've made sure that a quick breakdown of all the important info is right at the top.
In this case my main points are – I'm releasing an album – it's great – when it's out – where to get it.
I've capitalised the album title and my name just to drive it into peoples subconscious.
Technically I'm doing this right now. Some would say this whole article is a shameless attempt to link to my music, but hey ho.
Next up I popped a photo of the album's cover along with a tracklist. This is optional, as the people reading your press release will probably have a copy of your album anyway.
I used the press release to submit demos to radio stations too, so I made sure to include the length of songs was included here too.
A press release has to be eye catching and so it's a good idea to try and break up any big chunks of text wherever you can.
Try and imagine you're an underpaid journalist, who would rather be anywhere but in an office, on a Monday morning, reading your press release.
If it looks like you've transcribed a portion of the English patient onto a side of A4, you can imagine how unwilling anyone would be to read it.
If you haven't read the English Patient then just remove all the furniture from one of the rooms of your house and spend about twelve hours staring at a bare wall. That should give you a similar experience.
Here is the meat and potatoes of the one sheet – the blurb. to be honest, I imagined that 70% of the readers wouldn't bother getting this far unless they were interested (much like this blog post).
By this part of the press release, you want to have already given all the information that is important. This is your chance to just sell a few more sound bytes.
Try and think of a few things that could feed an interview or article should it follow – any interesting facts about the project or the people involved.
It is always good to write from the perspective of a third person and make sure not to overdo how much you big thing up. No one likes an egotist!
I broke the blurb into paragraphs which i felt could also stand alone sound bytes, name-dropping the odd track and using a few chose words to steer the tone of the description in the direction I felt would benefit it.
I also had a lovely little quote which conveniently mentioned some of my favourite artists, in the vain hope that I too may get mentioned in the same breath.
Remember to tweak the tone to suit different targets. If you're of local interest, you may want to big that up when sending to towns nearby. Conversely, you may not wish to mention that at all if you're press release is travelling further afield.
Know your product, tell them why the people involved had the unique perspective that created it.
Now, at the very bottom, you want to make sure the reader has links to whatever forms of contact or websites you're on.
It's also a good idea to reiterate the main points of your document.
Buy my album! That's what I'm saying here (feel it filter into your subconscious) I'm also taking the opportunity to feed them any links I may want them to visit.
Keep it straightforward and to the point. The name; 'one sheet' is literal to that degree.
So there you have it, a quick breakdown of what went into my one sheet.
Remember there are no strict rules as to how it should look but in order for it to be effective, you want to make it eye catching and to the point. Don't make the reader have to hunt for any info.
For every twenty you send out, only one or two may get you anything, so don't be disheartened. It's also often hard to tell whether you've had any response at all, so just keep sending them out and see what happens.
If you visit my web page for my album; The Melody Of Distaste, I will slowly put up any reviews I received and where applicable, link to the sites that were responsible.
Please feel free to submit your own music to them as well – if they reviewed me then they must be open to submissions!
Also, please share this article with as many musicians as you can – no one should be charged for this information.
Obviously, it's great if you visit my site etc, blah, blah, blah, but I spent many hours sifting through countless pages of bollox before piecing together what I was doing.
I hope this will save you that misfortune!
Anyway, as always, feel free to comment if anything isn't clear.


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Q: Sqlite date format in my app I am storing date and time in sqlite as timestamp value e.g.  1486650099741 when i use it in my code using setTimeinMillis for GregorianCalendar it converts perfectly. However when i try to year for the same time (in millis) using strftime ('%Y',datetimestamp) in sqlite it gives me weird results (year is shown as 1698 and not 2017)
is it something to do with the epoch (used by sqlite) ?

A: Please try this select strftime('%Y', datetimestamp/ 1000, 'unixepoch');

redpajama_set_name: RedPajamaStackExchange


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Latest > PGA Pro busted for solicitation
PGA Pro busted for solicitation
Operation Santa's Naughty List
Words: GolfPunk Photography: Getty Images
Tommy "Two Gloves" Gainey was arrested as part of a prostitution sting in Central Florida. Gainey has been a pro golfer since 1997 and joined the PGA Tour in 2008, where he became famous for wearing gloves on both hands when playing.
And for my next trick!
According to officials, Gainey was arrested during a sting operation dubbed "Operation Santa's Naughty List, using undercover detectives to target prostitution, human trafficking and child predators. The forty-four year old from South Carolina is facing a 1st-degree misdemeanor solicitation charge.
Gainey who has made four starts on the tour this season, including most recently the RSM Classic where he missed the cut, was due to take part in the final stage of Korn Ferry Tour Q-School which begins today.
The records show that Gainey was booked on 8 December and was released the following morning after posting bail of $500. In a press conference Sheriff Grady Judd stated:
"He's married. He told us he was here for a charity golf event and it was supposed to be in the next morning tee off. He didn't make it. He was a scratch."
Judd added, "We charged him with soliciting. He missed his tee time the next morning."
It's not looking good for the journeyman pro. It is not clear what action the tour will take but we assume his sponsors will take action to distance themselves from the golfer.
And another thing...
The trophy that set Twitter buzzing
TAGS: Tommy Two Gloves Gainey, golf pro arrested, golf solictation
Pete Dye dies at age of 94
New putters from the Master
Ping signs Eddie Pepperell
Please login to post a comment on an article
Top 5 Slowest Golfers Revisited
New slow kids on the block


You'd be hard-pushed to find a more enjoyable listen from a radio at this price.
"Alexa, play The Rolling Stones on my iStream 3". Control your iStream 3 via Alexa.
With built-in Spotify, Amazon Prime Music, Deezer and TIDAL, you have unlimited access to music at your fingertips.
Listen to thousands of radio stations from around the world.
Connect and playback from your smartphone via Bluetooth.
Control your iStream 3 from your smartphone via the free UNDOK app, or by using the on-device controls.
Built-in USB smartphone charger, to keep your battery topped up while listening.
No matter the look and feel of your room, the classic 1950s design will perfectly complement it – simply select your perfect colour to add even more style to your space.


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Q: how to parse a huge file with certain text I have this huge file and it has bunch of entries in it. I would like to only read entries that contain certain values like "db_call".
I have tried this:
df<-read.table(text=readLines("H:/ap.log")[grepl("db_call")])

I get this error:
argument "x" is missing, with no default
any ideas?

A: Create a test file:
writeLines(c("aaa 11","aaa 22","bbb 33"),con="test.txt")

The brute-force method (essentially the approach you tried above) is to read in the entire thing and then take only the pieces you want:
xx <- readLines("test.txt")
xx <- xx[grepl("aaa",xx,fixed=TRUE)]
##  (fixed=TRUE is slightly faster if you don't need regular expressions)
read.table(text=xx)

If you have a big file, I would recommend using grep at the system level (install Cygwin if necessary as you seem to be using Windows) and using pipe, e.g.
Test -- see how many lines contain the target string:
system('grep "aaa" <text.txt | wc')

Read only lines containg aaa:
read.table(pipe('grep "aaa" <test.txt'))

This will be much more efficient than reading the whole thing into R and then selecting the parts you want.


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Q: Why is Apache running so many processes? Excessive RAM here? I notice Apache is running multiple processes on my LAMP server (ubuntu 10.10). I'm just running a Wordpress site with MySQL as a database. It seems like www-data is running apache2 more than it should (using too much memory too), am I correct:
ID      Owner       Size        Command
31200   www-data    251236 kB   /usr/sbin/apache2 -k start
20678   www-data    250948 kB   /usr/sbin/apache2 -k start
25781   www-data    248888 kB   /usr/sbin/apache2 -k start
31045   www-data    248844 kB   /usr/sbin/apache2 -k start
19926   www-data    246480 kB   /usr/sbin/apache2 -k start
20749   www-data    239380 kB   /usr/sbin/apache2 -k start
32616   www-data    238632 kB   /usr/sbin/apache2 -k start
8846    mysql   238128 kB   /usr/sbin/mysqld
24178   www-data    234228 kB   /usr/sbin/apache2 -k start
32618   www-data    232344 kB   /usr/sbin/apache2 -k start
32615   www-data    232204 kB   /usr/sbin/apache2 -k start
19805   root    208156 kB   /usr/sbin/apache2 -k start

A: As the answer by Pawel explains, apache uses a process per request model with a process pool (or thread per request with mpm_worker).
You might be able to reduce the memory usage by using a web server based on non-blocking IO,
such as nginx. That way the server doesn't need to dedicate a process/thread per connection.

A: Apache will run as many processes as you configure it to. The configuration differs if you are using the prefork or worker multi-processing modules.

A: Apache is running multiple processes to have them ready when a client request comes in. Spawning a server process is slow, so it's best to have one waiting for a client.
For memory usage, you should take into the account RES size (as displayed by top), which is the amount of physical memory used by the task.
Why do you think you have too many apache2 processes using too much memory? What do you expect? Why do you expect so?


text:
Q: New and Delete operator on singly linked list in C++ #include <iostream>

#include <assert.h>

using namespace std;

struct node {

    int num;

    node *link;

};

int main (void) {

    node *head, *tail;

    tail = new node;

    head = tail;

    int i = 1;

    while (i < 20) {

        tail -> num = i;

        tail -> link = new node;

        assert(tail->link != NULL);

        tail = tail->link;

        i++;

    }

    tail -> num = i;

    tail -> link = head;

    for (int x = 0;x<100;x++) {

        cout<<head->num<<" ";

        head = head->link;

    }

    delete head;

    return 0;

}

This source code is running but I feel like the delete operator is wrong? Like out of place? It's not suppose to be head. I expect to delete all the new nodes. But how?

A: Each new needs a corresponding delete. As you have it, you're only deleting the head of the list. All the other nodes will leak memory.   Also, some weirdness with that extra node you allocate at the beginning for tail.
This is closer to what you want:
int main (void) {

    node *head, *tail;

    head = nullptr;
    tail = nullptr;

    int i = 1;

    // allocate 20 nodes into a list
    while (i < 20) {

        node* newNode = new node();
        newNode->num = i;
        newNode->link = nullptr;

        if (head == nullptr) {
           head = newNode;
           tail = newNode;
        } else {
           tail->link = newNode;
        }
        i++;
    }

    // print all the nodes out
    node* probe = head;
    while (probe) {
       cout << probe->num << " ";
       probe = probe->next;
    }

    // delete all the nodes in the list
    probe = head;
    while (probe) {
       node* n = probe;
       probe = probe->link;
       delete n;
    }

    // don't leave invalid state
    head = nullptr;
    tail = nullptr;

    return 0;

}


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En Vogue: The NBA's Runway
Posted on May 8, 2013 by Sirelle Carter
With the NBA Playoffs in full swing, we the fans are privy to all-access coverage, extending far beyond the games. Having said that, perhaps the most striking images are the off-court slam dunks and turnovers of today's NBA style icons.
Coco Chanel once proclaimed that, "Fashion fades, only style remains the same." A declaration that certainly summarizes the panache state of the National Basketball Association. Be that as it may, it seems to be widely unremembered how the league arrived to its present trendy era.
It was prior to the 2005-06 season that Commissioner David Stern implemented a mandatory dress code. Stern's regulations governed that "all players must dress in business or conservative attire while arriving and departing a game, on the bench while injured, and when conducting official NBA business." Almost immediately, the verdict was met with much indignation. Fast-forwarding to today, the pageantry of oversized jeans and fitted caps, marinated by complementary do-rags are long gone.
Initially loathed by the players of the past, superstars of the present have so strongly embraced the dress code, that many people seem to have forgotten it exists. Magazine spreads, tailored Italian suits and front row seats at Fashion Week are a sign of the times; as these elements now set the style standard of the NBA.
As they do with most things, the players have made style a league-wide competition. While several players are battling for the lead, it would be hard to argue that reigning MVP, LeBron James, isn't winning the couture arms race he arguably ignited.
In the spring of 2008, James appeared alongside Gisele Bündchen on the cover of American Vogue. It was then that the world grew conscious of James' luxury flair. Since then, the hardwood phenom has also twice appeared on the cover of GQ. But while his style is globally saluted, James stated in a March 2012 interview with British GQ that he doesn't have a preferred one. He declared, "I'm pretty flexible. It's all about confidence, man!"
The mode doesn't stop with the league's most valuable player. Various other top NBA stars have equally made a name for themselves in the fashion world. Since joining the New York Knicks in 2010, Amar'e Stoudemire has collaborated on a clothing line with designer Rachel Roy, and become a regular at both New York's Mercedes-Benz Fashion Week and the Met Gala. But Stoudemire's most notable coup may have been cozying up to American Vogue Editor-In-Chief, Anna Wintour. As a result, he was the subject of a feature editorial in the publication's April 2012 issue.
James and Stoudemire aren't the only ballers with Miss Wintour on speed dial, however. James' Miami Heat teammate, Dwyane Wade, has also established a relationship with the fashion maven. Wade appeared in the magazine twice last year, while also holding a joint signing with the editor during last fall's Fashion's Night Out.
There is a common denominator between the aforementioned players. They all play in "big market" cities, such as Miami and New York. But what if you play for a franchise in a smaller market.. are you lobbed out of the limelight? Not if you're Russell Westbrook! As point guard of the Oklahoma City Thunder, Westbrook's style of play on the court reflects his style off of it: showy and electric.
Prior to his injury — that has sidelined him for the remainder of the playoffs — Westbrook generated buzz with his post-game press conference attire. Red-framed glasses and flamboyant patterned, print shirts have become a trademark for the 24-year old.
Although Westbrook is limited to hidebound Oklahoma several months a year, he manages to stay fashionably relevant. He took in a plethora of the Spring 2013 shows in New York City last summer; most notably Billy Reid, and Richard Chai. And when GQ came calling to have him model — print shirts — for their January 2013 issue, the 6-foot-3 guard dished them the assist.
Reflecting, it seems that Commissioner Stern knew what he was doing when he implemented a dress code. Not to say that Stern took international fashion magazine spreads into account, necessarily, but the objective was to dress up the league. And whether it be LeBron James linking with Audemars Piguet, or Kobe Bryant being named ambassador for Hublot, one would find it difficult to suggest that the players aren't benefiting from a more polished NBA.
This entry was posted in Fashion, NBA, Sports and tagged Amare Stoudemire, Anna Wintour, April 2008 US Vogue cover, Audemars Piguet, Billy Reid, Carlos Campos, Carmelo Anthony, Coco Chanel, David Stern, Dwyane Wade, Gisele Bündchen, Kobe Bryant Hublot ambassador, LeBron James, Mercedes-Benz Fashion Week, NBA Playoffs, New York Knicks, Oklahoma City Thunder, Rachel Roy, Richard Chai, Russell Westbrook. Bookmark the permalink.
3 Responses to En Vogue: The NBA's Runway
Veryyyyyy well written and I totallllllly agree! I love D.Wade and Carmelo's style the most, but there's nothing more refreshing than a clean cut man *swoons*. Stern definitely had the right idea to incorporate a dress code!
http://www.manhattanjan.com
manhattanjan says:
I loved this!!! It's nothing more refreshing than a clean cut man… An athletic one at that! *Swoons*
Stern definitely was on the right track incorporating a dress code because we were all totally over seeing them dripping in gold chains while rocking baggy jeans and tall-tee's. This trend of being a style concious athlete only adds to their character I think.
Pingback: GQ Recap: March 2014 | Sirelle Carter Online


text:
Home BLOGS Know about Lucknow Metro
Know about Lucknow Metro
Lucknow Metro –
Rapid transit system under construction in the city of Lucknow, Uttar Pradesh.The commencement of civil works started on 27 September 2014.Lucknow Metro Rail Corporation Limited a joint venture of the Government of India and the Government of Uttar Pradesh entrusted to build and operate the Lucknow Metro. The project will be the most expensive public transport system in the state. Total cost of phase 1 and 2 will be about $2 billion, of which ₹6,928 crore (US$1 billion) is being spent on phase 1. Partial commercial operation of Line 1 from Transport Nagar to Lucknow Charbagh Railway Station a distance of 8.5 km is started from 5 th September 2017. Lucknow Metro will have 2 Lines, the North-South line and the East-West line. The North-South corridor starts at Airport and goes to Munshi Pulia, with a total length of 22.878 kilometres (14.216 miles). The East-West corridor starts at Charbagh Railway Station and ends at Vasant Kunj. Both lines will intersect at Charbagh Railway Station.
Initially Lucknow Metro Rail Project was planned to include two corridors: North-South and East-West; and the Gomti Nagar link. The construction cost was estimated at Rs74.13 billion for North-South corridor, Rs 48.79 billion for East-West corridor and Rs4.95 billion for Gomti Nagar link.The North-South corridor was to connect Amausi airport to Munshipulia and cover a distance of 23 kilometres (14 mi), including 19.051 km elevated (11.838 mi), 0.774 km ramp (0.481 mi) and 3.053 km underground (1.897 mi).This corridor will have a total 22 stations including 19 overhead and 3 underground.The elevated stations would have included the Airport terminal, Amausi, Transport Nagar, Krishna Nagar, Singaar Nagar, Alambagh, ISBT, Mawaiya, Durgapuri, Charbagh. This shall be followed by an underground section that will include Hussain Ganj, Sachivalaya (Uttar Pradesh Secretariat) and Hazratganj. Here after, the track will be elevated again, stations in the sequence are KD Singh Babu Stadium, Lucknow University, IT College, Badshahnagar, Lekhraj Market, Ramsagar Mishra Nagar, Indira Nagar and a new terminus Munshi Pulia. For the Gomti Nagar link, the train coming from the airport terminal was to be diverted towards Gomti Nagar at the Indira Nagar trisection Polytechnic crossing along an elevated route. The planned stations were Indira Nagar Trisection, West End Mall [Waves Multiplex], Gomti Nagar & Patrakarpuram.The East-West corridor was planned to connect the Lucknow railway station at Charbagh to Vasantkunj on Hardoi Road and have a total length of 11 km (6.8 mi), including 4.29 km elevated (2.67 mi), 0.5 km ramp (0.31 mi) and 6.3 km underground (3.9 mi). This corridor was to have 12 stations including seven underground and five overhead. The stations at Lucknow Railway Station (Charbagh), Gautam Buddha Marg, Aminabad, Pandeyganj, Chattrapati Shahuji Maharaj Medical University (King George Medical University) and Niwazganj were to be below ground level, and an elevated section for the Thakurganj, Balaganj, Sarfarazganj, Moosabagh and the Vasant Kunj terminal stations.
The designed speed of metro would be 90 km/h (56 mph) while the scheduled speed would be 34 km/h (21 mph) for North-South corridor and 32 km/h (20 mph) for East-West corridor. There would be only one depot at Vasant Kunj spread over a land measuring 20 hectares (49 acres). The Amausi Depot has been done away because of its proximity to the Airport and the subsequent reasons of security and safety.
In 2013, the Department of Urban Planning did away with the two-corridor layout and recommended a dense network of metro connectivity in Lucknow. The entire route has been proposed to be built overhead. Due to this, the overall cost of the project will go up due to an expanded network, the operating cost per km will be reduced. This is because the cost of constructing one km of overhead track is ₹1.8 billion (US$28 million) as compared to ₹5.5 billion (US$86 million) for an underground track. Also, an underground track consumes much more energy and is less safe. There is also a proposal to start a Bus Rapid Transit System (BRTS) as a feeder service to the metro.
Funding of Lucknow Metro-
The state government and the central government provided funds for Lucknow Metro for first phase in the financial budget of 2014–2015 and 2015–2016.The state government provided funds for initial stage of surveys and construction of Headquarter of Lucknow Metro in 2012 and 2013 also. Lucknow Metro got clearance from PIB in December 2015. The Lucknow Metro has its own governing body, namely Lucknow Metro Rail Corporation situated in Gomti Nagar, Lucknow.
Infrastructure –
On 5 October 2015, French Engineering Firm Alstom bagged over 150 million euro contract to provide train coaches to Lucknow Metro. Lucknow Metro will initially have 20 train sets of 4 car each making a total of 80 cars. The trains will manufactured indigenous at Sricity plant of Alstom India.
2.90 m wide modern rolling stock with stainless steel body.
Axle load – 16 T
Seating arrangement – Longitudinal
Capacity of 6 coach unit – 1574 Passengers
Class of accommodation – One
Power supply –
The Lucknow Metro is supplied by a high-power 132-KV connection from UPPCL's Sarojini nagar 400-KV substation, the most powerful grid substation in the city.
Signaling –
Alstom has won the contract of providing signaling and train-sets for Lucknow Metro. The system will make use of advance signaling based on CBTC, Alstom will be installing its state of art Urbalis signaling system based on CBTC. The system will be designed with 100s headway in mind.
Design of metro coach
French multinational Alstom is manufacturing the Metro train at its facility in South India. The front of the Metro has been conceived to portray the essence of some of Lucknow's most iconic monuments, including Bara Imambara, Asifi mosque and the Roomi Gate, which is the signature edifice of the city. The Metro train's exterior livery in golden hue is inspired by the traditional Chikankari craft of Lucknow. The blending of black in front is inspired from the modern feel of Hazratganj, Lucknow's main commercial hub in the heart of city. Name of stations will be displayed in Hindi, Urdu and English on LCD screen.
Automatic fare collection (AFC)
An Indian firm and a Czech company were awarded the contract for providing the Automatic Fare Collection (AFC) system for the North-South corridor of Lucknow Metro in May 2016.
Personalized FM Radio Station
Lucknow metro will become the first metro in the country to have its own FM radio station along with a collaboration with private radio station to provide information regarding metro safety as well as on and off board entertainment. This service aims for infotainment and monetary purpose.
Bridge over river Gomti
A special bridge is planned over Gomti River for metro crossing near university. Its pillars are planned to be 10 to 15 meters deeper than normal bridges and is planned to be around 42 to 48 meters at various depths.
Lucknow metro will be providing WiFi to its passengers at each metro station. WiFi service will be free for all the 'Go Smart' Card holders, which holds various other benefits as well.
Lucknow metro will become the first metro in India to provide Commuters with free purified and chilled drinking water along with free toilet services at all of its stations.
Metro stations
Chaudhary Charan Singh International Airport
Amausi
Transport Nagar
Singaar Nagar
ISBT Alambagh
Mawaiya
Durgapuri
Lucknow Charbagh Railway Station(Junction. Connected with Blue Line)
Hussain Ganj
Sachivalaya
Hazratganj
KD Singh Babu Stadium
Lucknow University
IT Chauraha
Mahanagar
Badshahnagar
Lekhraj Market
Ramsagar Mishra Nagar
Munshi Pulia
Lucknow Charbagh Railway Station(Junction. Connected with Red Line)
Gautam Buddha Marg
Aminabad
Pandeyganj
Lucknow City Railway Station
Medical College Chauraha
Nawazganj
Thakurganj
Sarfarazganj
Musabagh
Phase 1A
Trial runs started in December 2016 and commercial operation is to begin on 05-Sep-2017.
Phase 1B
The phase 1B of Lucknow Metro will be completed by 2019.
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