NanoComputer

Alta Devices, a Silicon Valley startup, has found a way to synthesize Gallium onto a thin film, and the resulting solar cells can convert up to 30.8% of the energy from light into electricity. Gallium arsenide is better-able to capture light than traditional solar cells, and is currently used in space-bound craft such as satellites. Until now gallium arsenide has been synthesized in a crystalline form — quite cumbersome to add onto a mobile device. New Zealand nanotechnologist Brendan Kayes, who has worked at Alta Devices since 2009, is developing solar cells so efficient and lightweight they increase battery life on mobile devices by up to 80 per cent.

“Our technology provides several times the power per unit area of the best flexible solar options currently available for consumer devices,” Dr Kayes said. “We can fit four to five of our cells on the back of a cellphone. That means roughly one watt of charge under direct sun. “Every minute the phone is in the sun you get a minute of talking time,” he said.
Source: http://www.altadevices.com/

Researchers from Ulsan National Institute of Science and Technology – Korea – (UNIST) demonstrated high-performance polymer solar cells (PSCs) with power conversion efficiency (PCE) of 8.92% which is the highest values reported to date for plasmonic PSCs using metal nanoparticles (NPs).

“This is the first report introducing metal NPs between the hole transport layer and active layer for enhancing device performance. The multipositional and solutions-processable properties of our surface plasmon resonance (SPR) materials offer the possibility to use multiple plasmonic effects by introducing various metal nanoparticles into different spatial location for high-performance optoelectronic device via mass production techniques.” said Prof. Jin Young Kim who led the study with Prof.Soojin Park from UNIST. “Our work is meaningful to develop novel metal nanoparticles and almost reach 10% efficiency by using these materials. If we continuously focus on optimizing this work, commercialization of PSCs will be a realization but not dream,” added Prof. Park.

A polymer solar cell is a type of thin film solar cells made with polymers that produce electricity from sunlight by the photovoltaic effect. Most current commercial solar cells are made from a highly purified silicon crystal. The high cost of these silicon solar cells and their complex production process has generated interest in developing alternative photovoltaic technologies.

Source: http://www.unist.ac.kr

Throughout decades of research on solar cells, one formula has been considered an absolute limit to the efficiency of such devices in converting sunlight into electricity: Called the Shockley-Queisser efficiency limit, it posits that the ultimate conversion efficiency can never exceed 34 percent for a single optimized semiconductor junction. Now, researchers at the Massachusetts Institute of Technology – MIT – have shown that there is a way to blow past that limit as easily as today’s jet fighters zoom through the sound barrier — which was also once seen as an ultimate limit. Their work appears this week in a report in the journal Science.

singlet exciton fission. (An exciton is the excited state of a molecule after absorbing energy from a photon.)
While today’s commercial solar panels typically have an efficiency of at most 25 percent, a silicon solar cell harnessing singlet fission should make it feasible to achieve efficiency of more than 30 percent, Baldo says — a huge leap in a field typically marked by slow, incremental progress. In solar cell research, he notes, people are striving “for an increase of a tenth of a percent.”

Solar panel efficiencies can also be improved by stacking different solar cells together, but combining solar cells is expensive with conventional solar-cell materials. The new technology instead promises to work as an inexpensive coating on solar cells.

Source: http://web.mit.edu/

Professor Dong Rip Kim from Hangyang University – Korea – has succeeded in fabricating peel-and-stick thin film solar cells (TFSCs) with the collaboration of Stanford team led by Professor Xiaolin Zheng. This method makes possible the overcoming of hardships related to working with traditional solar cells, namely the lack of handling, high manufacturing cost, and limited flexibility while maintaining performance. Kim is currently in charge of the Hanyang University Nanotechnology for Energy Conversion Lab. His research interests are solar cells, energy conversion devices using nanomaterials, flexible electronics, nanoelectronics, and nanosensors. Among Kim’s recent publications are “Peel-and-Stick: Fabricating Thin Film Solar Cell on Universal Substrates” in the journal of Scientific Reports, “Shrinking and Growing: Grain Boundary Density Reduction for Efficient Polysilicon Thin-Film Solar Cells” in the journal of Nano Letters, and “Thermal Conductivity in Porous Silicon Nanowire Arrays” in the journal of Nanoscale Research Letters.

“I will continue to focus on creating highly efficient but low costing energy conversion devices with nanotechnology,” Kim said. Moreover, his future research will focus on applying his method in other types of solar cells and in other applications.

Source: http://www.hanyang.ac.kr/

Scientists at Aalto University, Finland and Fraunhofer ISE, Germany report an efficiency of 18.7% for black silicon solar cells, the highest efficiency reported so far for a black silicon solar cell.
The researchers were able to apply a boron diffusion to create a pn-junction, maintaining the excellent optical properties of the black silicon structure. By applying atomic layer deposited Al203, an effective passivation of the nanostructured surfaces was achieved. The previous efficiency record of 18.2% was held by the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) using thermal oxidation as a passivating layer.

“The quantum efficiency measurements reveal that the nanostructured front surface is of a high electrical quality comparable to a pyramidal textured surface”, says Assistant Professor Hele Savin of Aalto University.
Routes for improving the cell efficiency are already identified, and efficiencies clearly above 20% should be within reach.
Source: http://www.aalto.fi/

A Stanford team has designed an entirely new form of cooling panel that works even when the sun is shining. Such a panel could vastly improve the daylight cooling of buildings, cars and other structures by radiating sunlight back into the chilly vacuum of space.
In the future we can imagine homes and buildings chilled without air conditioners. Car interiors that don’t heat up in the summer sun. Tapping the frigid expanses of outer space to cool the planet. Science fiction, you say? Well, maybe not any more.

“People usually see space as a source of heat from the sun, but away from the sun outer space is really a cold, cold place,” explained Shanhui Fan, professor of electrical engineering and the paper’s senior author. “We’ve developed a new type of structure that reflects the vast majority of sunlight, while at the same time it sends heat into that coldness, which cools manmade structures even in the day time.”

Source: http://engineering.stanford.edu/

Scientists from the Nano-Science Center at the Niels Bohr Institut, Denmark and the Ecole Polytechnique Fédérale de Lausanne, Switzerland, have shown that a single nanowire can concentrate the sunlight up to 15 times of the normal sun light intensity. The results are surprising and the potential for developing a new type of highly efficient solar cells is great.

Due to some unique physical light absorption properties of nanowires, the limit of how much energy we can utilize from the sun’s rays is higher than previous believed. These results demonstrate the great potential of development of nanowire-based solar cells, says PhD Peter Krogstrup on the surprising discovery that is described in the journal Nature Photonics.
Source: http://www.nbi.ku.dk/

A new technique developed by University of Toronto Engineering Professor Ted Sargent and his research group could lead to significantly more efficient solar cells. The solution? Spectrally tuned, solution-processed plasmonic nanoparticles. These particles, the researchers say, provide unprecedented control over light’s propagation and absorption. The new technique developed by Sargent’s group shows a possible 35 per cent increase in the technology’s efficiency in the near-infrared spectral region, says co-author Dr. Susanna Thon. Overall, this could translate to an 11 per cent solar power conversion efficiency increase, she says, making quantum dot photovoltaics even more attractive as an alternative to current solar cell technologies.

“There are two advantages to colloidal quantum dots,” Thon says. “First, they’re much cheaper, so they reduce the cost of electricity generation measured in cost per watt of power. But the main advantage is that by simply changing the size of the quantum dot, you can change its light-absorption spectrum. Changing the size is very easy, and this size-tunability is a property shared by plasmonic materials: by changing the size of the plasmonic particles, we were able to overlap the absorption and scattering spectra of these two key classes of nanomaterials.”

Source: http://media.utoronto.ca/

The silicon solar cells that are used to supply electricity for domestic use are relatively cheap, but inefficient because they are only able to utilise a limited part of the effect of the sunlight. The reason is that one single material can only absorb part of the spectrum of the light. Now researchers at Lund University in Sweden have shown how nanowires could pave the way for more efficient and cheaper solar cells. Research on solar cell nanowires is on the rise globally. Until now the unattained dream figure was ten per cent efficiency – but now Dr Borgström and his colleagues are able to report an efficiency of 13.8 per cent.

“Our findings are the first to show that it really is possible to use nanowires to manufacture solar cells”, says Magnus Borgström, a researcher in semiconductor physics and the principal author.
Source: http://www.lunduniversity.lu.se

Scientists at Aalto University – Finland, have demonstrated results that show a huge improvement in the light absorption and the surface passivation of silicon nanostructures. This has been achieved by applying atomic layer coating. The results advance the development of devices that require high sensitivity light response such as high efficiency solar cells.

- This method provides extremely good surface passivation. Simultaneously, it reduces the reflectance further at all wavelengths.These results are very promising considering the use of black silicon (b-Si) surfaces on solar cells to increase the efficiency to completely new levels, tells researcher scientist. Päivikki Repo.
More effective surface passivation methods than those used in the past have been needed to make black silicon a viable material for commercial applications. Good surface passivation is crucial in photonic applications such as solar cells. The research has just been published in the Journal of Photovoltaics. The research is carried out by Aalto University, Finland, together with experts from Fraunhofer Institute for Solar Energy Systems ISE, Germany.
Source: http://www.aalto.fi

Princeton researchers have found a simple and economical way to nearly triple the efficiency of organic solar cells, the cheap and flexible plastic devices that many scientists believe could be the future of solar power. The researchers, led by electrical engineer Stephen Chou, were able to increase the efficiency of the solar cells 175 percent by using a nanostructured “sandwich” of metal and plastic that collects and traps light. Chou said the technology also should increase the efficiency of conventional inorganic solar collectors, such as standard silicon solar panels, although he cautioned that his team has not yet completed research with inorganic devices.

“Our goal is to extend high-performance electronic and solar-cell function to longer lengths and to more flexible forms. We already have made meters-long fibers but, in principle, our team’s new method could be used to create bendable silicon solar-cell fibers of over 10 meters in length,” one of the Princeton team researcher said. “Long, fiber-based solar cells give us the potential to do something we couldn’t really do before: We can take the silicon fibers and weave them together into a fabric with a wide range of applications such as power generation, battery charging, chemical sensing and biomedical devices.”
Source: http://www.princeton.edu/

Scientists from Ecole Polytechnique Fédérale de Lausanne (EPFL) – Switzerland – are producing hydrogen from sunlight, water and rust. They’re paving the way for an economic and ecological solution for storing renewable energy. How can solar energy be stored so that it can be available any time, day or night, when the sun shining or not? EPFL scientists are developing a technology that can transform light energy into a clean fuel that has a neutral carbon footprint: hydrogen. The basic ingredients of the recipe are water and metal oxides, such as iron oxide, better known as rust. Kevin Sivula and his colleagues purposefully limited themselves to inexpensive materials and easily scalable production processes in order to enable an economically viable method for solar hydrogen production. The device, still in the experimental stages, is described in an article published in the journal Nature Photonics.

Their prototypes shared the same basic principle: a dye-sensitized solar cell – invented by Michael Grätzel, a colleague from University of Geneva, – combined with an oxide-based semiconductor. The device is completely self-contained.

Source: http://actu.epfl.ch/

Researchers from North Carolina State University have created flower-like structures out of germanium sulfide (GeS) – a semiconductor material – that have extremely thin petals with an enormous surface area. The GeS flower holds promise for next-generation energy storage devices and solar cells.

“Creating these GeS nanoflowers is exciting because it gives us a huge surface area in a small amount of space,” says Dr. Linyou Cao, an assistant professor of materials science and engineering at NC State and co-author of a paper on the research. “This could significantly increase the capacity of lithium-ion batteries, for instance, since the thinner structure with larger surface area can hold more lithium ions. By the same token, this GeS flower structure could lead to increased capacity for supercapacitors, which are also used for energy storage.”

Source: http://news.ncsu.edu/releases/wms-cao-flower/

Solar panels, like those commonly perched atop house roofs or in sun-drenched fields, quietly harvesting the sun’s radiant energy, are one of the standard-bearers of the green energy movement. But could they be better – more efficient, durable and affordable? That’s what engineers from Drexel University and The University of Pennsylvania are trying to find out, with the aid of a little nanotechnology and a lot of mathematical modeling.

A three-year grant from the National Science Foundation has set the team on a track to explore ways to make new photoelectric cells more efficient, durable and affordable. The group is examining “dye-sensitized” solar panels, which capture radiation via photosensitive dye and convert it into electricity. Their goal: streamline the electron transfer process inside the solar panels to make them more efficient at converting the radiation into electricity. Dye-sensitized solar panels currently convert about 11 to 12 percent of the sunlight that hits them into electricity. The researchers are pushing to make these panels at least as efficient as their silicon counterparts, which currently convert about twice as much radiation as the dye-sensitized panels.

Source: http://www.drexel.edu/now/news-media/releases/archive/2012/August/Dye-sensitized-solar-panel-research/

Collecting solar energy to convert to electricity is not a new concept. However, there are significant advantages to space solar power compared to ground solar power. Solar energy in space is seven times greater per unit area than on the ground. The collection of solar space energy is not disrupted by nightfall and inclement weather, thus avoiding the need for expensive energy storage. You can see the findings from The National Space Society (NSS)   pusblished a few months ago, a ground-breaking space solar power study conducted by the  International Academy of Astronautics (IAA).

With space solar power technology, energy can be collected from space and transmitted wirelessly anywhere in the world,” said Mark Hopkins, the leading Executive Officer of the National Space Society. “This technology could be the answer to our energy crisis. We look forward to sharing the results of the IAA’s study, and exploring the potential that space solar power has for creating thousands of green energy jobs,” he added.

Source: http://blog.nss.org/
http://www.nss.org/settlement/ssp/library/SSPprizes2011.pdf 

University of California, San Diego electrical engineers are building a forest of tiny nanowire trees in order to cleanly capture solar energy without using fossil fuels and harvest it for hydrogen fuel generation. Deli Wang, professor in the Department of Electrical and Computer Engineering at the UC San Diego  Jacobs School of Engineering says that current technology uses fossil fuels to convert/separate hydrogen. The new method will not produce any greenhouse gases.

Electronic microscopic image of a nanoforest, or “3D branched nanowire array.” Green tint added for contrast. Image credit: Wang Research Group, UC San Diego Jacobs School of Engineering.

Their "3D branched nanowire array" uses a process called photoelectrochemical water-splitting to produce hydrogen gas. The arrays are made of zinc-oxide and silicon which are cheap abundant elements.

Why use nanowire forests? Wang says there are two reasons. The first reason is because forests tend to absorb solar energy while flat deserts and oceans tend to reflect it. When the light gets trapped in the forest the energy is used to separate the water into its constituents, hydrogen and oxygen. The technology is similar to a retinal photoreceptor cells in the human eye.

Soure: http://www.jacobsschool.ucsd.edu/news/news_releases/release.sfe?id=1177

Researchers at CRANN, the Science Foundation Ireland funded nanoscience institute based in Trinity College Dublin (TCD), have discovered a new material that could transform the quality, lifespan and efficiency of flat screen computers, televisions and  solar cells.  The research team was led by Prof Igor Shvets, a CRANN, a  Principal Investigator who comments: "this is an exciting development with a range of applications and we are hopeful this initial research will attract commercial interest in order to explore its industrial use.  The new material could lead to innovations such as window-integrated flat screens and to increase the efficiency of certain solar cells, thus significantly impacting on the take-up of solar cells, which can help us to reduce carbon emissions.”

Devices that the new material could be used with such as solar cells, flat screen TVs, computer monitors, LEDs all utilise materials that can conduct electricity and at the same time are see-through.  These devices currently use transparent conducting oxides, which are a good compromise between electrical conductivity and optical transparency. They all have one fundamental limitation: they all conduct electricity through the movement of electrons

Source: http://apl.aip.org/resource/1/applab/v99/i11/p111910_s1?isAuthorized=no

Imagine a world where the windows of high-rise office buildings are powerful energy producers, offering its inhabitants much more than some fresh air, light and a view. For the past four years a team of researchers from Flinders University has been working to make this dream a reality – and now the notion of solar-powered windows could be coming to a not too distant future near you. As part of his just-completed PhD, Dr Mark Bissett from the School of   Chemical and Physical Sciences - Australia, has developed a revolutionary solar cell using carbon nanotubes. A promising alternative to traditional silicon-based solar cells, carbon nanotubes are cheaper to make and more efficient to use than their energy-sapping, silicon counterparts.

“Solar power is actually the most expensive type of renewable energy – in fact the silicon solar cells we see on peoples’ roofs are very expensive to produce and they also use a lot of electricity to purify,” Dr Bissett said. He added that  the new, low-cost carbon nanotubes are transparent, meaning they can be “sprayed” onto windows without blocking light, and they are also flexible so they can be weaved into a range of materials including fabric – a concept that is already being explored by advertising companies.

Source: http://blogs.flinders.edu.au/flinders-news/2012/03/19/solar-cell-turns-windows-into-generators/

Imec, Polyera and international chemical group Solvay have achieved a new world-record efficiency of 8.3% for polymer-based single junction organic solar cells in an inverted device stack. These excellent performance results represent a crucial step towards successful commercialization of organic photovoltaic cells.

Solar power is gradually becoming cost-competitive with traditional mainstream energy sources such as coal, oil, and nuclear. Continued reduction of manufacturing and installation costs of solar panels will further drive this cost-competitiveness. Organic solar cells are holding the promise of addressing these issues, due to their potential to be manufactured on large-areas at high-throughput, and on lightweight, flexible substrates (like plastic or textiles), significantly reducing transportation and installation costs. This, along with optical translucency, gives organic solar cells the potential to be cheaply integrated into everything from clothing to building facades and windows.

Source: http://www2.imec.be/be_en/press/imec-news/imecpolyerasolvayopv.html