CdTe ink makes high-efficiency solar cell


Chicago CdE pic1Cadmium telluride nanocrystal colloids could be used as the photovoltaic “ink” in solar cells, according to new experiments by researchers at the National Renewable Energy Laboratory and the University of Chicago. Devices made using CdTe layers as thin as just 330 nm have a sunlight-to-power conversion of efficiency of 10% while those made with 550 nm thick layers have an efficiency of more than 11%. They also boast an impressive blue light response of nearly 80% external quantum efficiency – something that allows for improved photocurrent from these cells.

Thin-film photovoltaic materials could be alternatives to traditional silicon-based solar-cell materials because they absorb sunlight more efficiently – thanks to the fact that they have direct rather than indirect bandgaps. This means that less material, weight for weight, is needed to absorb the same amount of solar radiation. What is more, thin-film photovoltaics, such as cadmium telluride, can be easily and cheaply deposited onto a wide range of flexible and rigid substrates in solution.

Chicago CdE pic1

Spheres, faceted nanocrystals and tetrapods

There is a problem, however, in that the power-conversion efficiencies of thin-film materials that have been processed from solution are typically lower than those produced by traditional vapour deposition techniques.

Now, a team led by Dmitri Talapin of Chicago and Joseph Luther at NREL has succeeded in synthesizing CdTe inks from solutions of nanocrystals that have controllable shapes, ranging from spheres to tetrapods, and controllable crystallographic phases: wurtzite and zincblende. The researchers found that the best performing solar-cell devices are those containing tetrapodal-shaped nanocrystals in the wurtzite phase. Following a relatively low-temperature short anneal, these crystals undergo a critical phase change from wurtzite to zincblende that coincides with the small grain soluble nanocrystals growing into large grain, photovoltaic quality, CdTe.

Layer-by-layer approach

“Rather than depositing the whole CdTe layer at once, we use a layer-by-layer approach to build up a very thin layer of the CdTe and control the grain growth,” explains team member Ryan Crisp, graduate student at the Colorado School of Mines. “We then deposit more nanocrystals and repeat the process until we reach the desired layer thickness.”

As the nanocrystals change phase and sinter (or grow) together, they form polycrystalline films, he adds. These films are unique in that they are exceptionally smooth and uniform (compared with films that are produced by traditional sublimation methods). “This means that further layers have a ‘nice’ surface on which we can deposit without fear of encountering short-circuits caused by irregularities and defects,” he tells nanotechweb.org.

“The crystal grains in our material extend from the top to the bottom in a finished device, allowing us to efficiently extract charge carriers (in this case photoexcited electrons) from it. We are able to do this since the electrons do not encounter many grain boundaries – something that minimizes their chance of being ‘lost’ to defect traps as they travel through the structure.”

Higher-efficiency, lower-cost devices

Solar cells made from the CdTe ink boast a sunlight-to-power conversion efficiency of 10–12%. This value might be further improved by placing the ink on the right type of substrate. “By employing this inexpensive solution-processed ink (instead of the more expensive, and slower throughput thin-film photovoltaic materials produced by sublimation), we can make potentially higher-efficiency, lower-cost devices,” says Crisp. “We explored several device structures and found that the ink-based films perform better in a simple ITO/CdTe/ZnO/Al structure rather than the traditional structure with CdS and ZnTe contacts.”

The main limiting factor to improving device efficiency is increasing the open circuit voltage. “We now plan on improving the quality of the ITO/CdTe interface (used in our highest efficiency device) to do this – and in particular by better controlling the energy levels (that is the band alignment) of the materials at this interface,” adds Crisp.

The new photovoltaic ink is described in ACS Nano

The World Of Tomorrow: Nanotechnology: Interview with PhD and Attorney D.M. Vernon


Bricks and Mortar chemistsdemoThe Editor interviews Deborah M. VernonPhD, Partner in McCarter & English, LLP’s Boston office.

 

 

 

Why It Matters –

” … I would say the two most interesting areas in the last year or two have been in 3-D printing and nanotechnology. 3-D printing is an additive technology in which one is able to make a three-dimensional product, such as a screw, by adding material rather than using a traditional reduction process, like a CNC (milling) process or a grinding-away process.

The other interesting area has been nanotechnology. Nanotechnology is the science of materials and structures that have a dimension in the nanometer range (1-1,000 nm) – that is, on the atomic or molecular scale. A fascinating aspect of nanomaterials is that they can have vastly different material properties (e.g., chemical, electrical, mechanical properties) than their larger-scale counterparts. As a result, these materials can be used in applications where their larger-scale counterparts have traditionally not been utilized.”

nanotech

Editor: Deborah, please tell us about the specific practice areas of intellectual property in which you participate.

 

 

Vernon: My practice has been directed to helping clients assess, build, maintain and enforce their intellectual property, especially in the technology areas of material science, analytical chemistry and mechanical engineering. Prior to entering the practice of law, I studied mechanical engineering as an undergraduate and I obtained a PhD in material science engineering, where I focused on creating composite materials with improved mechanical properties.

Editor: Please describe some of the new areas of biological and chemical research into which your practice takes you, such as nanotechnology, three-dimensional printing technology, and other areas.

Vernon: I would say the two most interesting areas in the last year or two have been in 3-D printing and nanotechnology. 3-D printing is an additive technology in which one is able to make a three-dimensional product, such as a screw, by adding material rather than using a traditional reduction process, like a CNC (milling) process or a grinding-away process. The other interesting area has been nanotechnology. Nanotechnology is the science of materials and structures that have a dimension in the nanometer range (1-1,000 nm) – that is, on the atomic or molecular scale.

A fascinating aspect of nanomaterials is that they can have vastly different material properties (e.g., chemical, electrical, mechanical properties) than their larger-scale counterparts. As a result, these materials can be used in applications where their larger-scale counterparts have traditionally not been utilized.

Organ on a chip organx250

I was fortunate to work in the nanotech field in graduate school. During this time, I investigated and developed methods for forming ceramic composites, which maintain a nanoscale grain size even after sintering. Sintering is the process used to form fully dense ceramic materials. The problem with sintering is that it adds energy to a system, resulting in grain growth of the ceramic materials. In order to maintain the advantageous properties of the nanosized grains, I worked on methods that pinned the ceramic grain boundaries to reduce growth during sintering.

The methods I developed not only involved handling of nanosized ceramic particles, but also the deposition of nanofilms into a porous ceramic material to create nanocomposites. I have been able to apply this experience in my IP practice to assist clients in obtaining and assessing IP in the areas of nanolaminates and coatings, nanosized particles and nanostructures, such as carbon nanotubes, nano fluidic devices, which are very small devices which transport fluids, and 3D structures formed from nanomaterials, such as woven nanofibers.

Editor: I understand that some of the components of the new Boeing 787 are examples of nanotechnology.

Vernon: The design objective behind the 787 is that lighter, better-performing materials will reduce the weight of the aircraft, resulting in longer possible flight times and decreased operating costs. Boeing reports that approximately 50 percent of the materials in the 787 are composite materials, and that nanotechnology will play an important role in achieving and exceeding the design objective. (See, http://www.nasc.com/nanometa/Plenary%20Talk%20Chong.pdf).

While it is believed that nanocomposite materials are used in the fuselage of the 787, Boeing is investigating applying nanotechnology to reduce costs and increase performance not only in fuselage and aircraft structures, but also within energy, sensor and system controls of the aircraft.

Editor: What products have incorporated nanotechnology? What products are anticipated to incorporate its processes in the future?

Vernon: The products that people are the most familiar with are cosmetic products, such as hair products for thinning hair that deliver nutrients deep into the scalp, and sunscreen, which includes nanosized titanium dioxide and zinc oxide to eliminate the white, pasty look of sunscreens. Sports products, such as fishing rods and tennis rackets, have incorporated a composite of carbon fiber and silica nanoparticles to add strength. Nano products are used in paints and coatings to prevent algae and corrosion on the hulls of boats and to help reduce mold and kill bacteria. We’re seeing nanotechnology used in filters to separate chemicals and in water filtration.

The textile industry has also started to use nano coatings to repel water and make fabrics flame resistant. The medical imaging industry is starting to use nanoparticles to tag certain areas of the body, allowing for enhanced MRI imaging. Developing areas include drug delivery, disease detection and therapeutics for oncology. Obviously, those are definitely in the future, but it is the direction of scientific thinking.

Editor: What liabilities can product manufacturers incur who are incorporating nanotechnology into their products? What kinds of health and safety risks are incurred in their manufacture or consumption?Nano Body II 43a262816377a448922f9811e069be13

Vernon: There are three different areas that we should think about: the manufacturing process, consumer use and environmental issues. In manufacturing there are potential safety issues with respect to the incorporation or delivery of nanomaterials. For example, inhalation of nanoparticles can cause serious respiratory issues, and contact of some nanoparticles with the skin or eyes may result in irritation. In terms of consumer use, nanomaterials may have different material properties from their larger counterparts.

As a result, we are not quite sure how these materials will affect the human body insofar as they might have a higher toxicity level than in their larger counterparts. With respect to an environmental impact, waste or recycled products may lead to the release of nanoparticles into bodies of water or impact wildlife. The National Institute for Occupational Safety and Health has established the Nanotechnology Research Center to develop a strategic direction with respect to occupational safety and nanotechnology. Guidance and publications can be found at http://www.cdc.gov/niosh/topics/nanotech.

Editor: The European Union requires the labeling of foods containing nanomaterials. What has been the position of the Food & Drug Administration and the EPA in the United States about food labeling?

Vernon: So far the FDA has taken the position that just because nanomaterials are smaller, they are not materially different from their larger counterparts, and therefore there have been no labeling requirements on food products. The FDA believes that their current standards for safety assessment are robust and flexible enough to handle a variety of different materials. That being said, the FDA has issued some guidelines for the food and cosmetic industries, but there has not been any requirement for food labeling as of now. The EPA has a nanotechnology division, which is also studying nanomaterials and their impact, but I haven’t seen anything that specifically requires a special registration process for nanomaterials.

Editor: What new regulations regarding nanotech products are expected? Should governmental regulations be adopted to prevent nanoparticles in foods and cosmetics from causing toxicity?

Vernon: The FDA has not telegraphed that any new regulations will be put into place. The agency is currently in the data collection stage to make sure that these materials are being safely delivered to people using current FDA standards – that materials are safe for human consumption or contact with humans. We won’t really understand whether or not regulations will be coming into place until we see data coming out that indicates that there are issues that are directly associated with nanomaterials. Rather than expecting regulations, I would suggest that we examine the data regarding nano products to optimize safe handling and use procedures.

Editor: Have there ever been any cases involving toxicity resulting from nano products?

Vernon: There are current investigations about the toxicity of carbon nano tubes, but the research is in its infancy. There is no evidence to show any potential harm from this technology. Unlike asbestos or silica exposure, the science is not there yet to demonstrate any toxicity link. The general understanding is that it may take decades for any potential harm to manifest. I believe my colleague, Patrick J. Comerford, head of McCarter’s product liability team in Boston, summarizes the situation well by noting that “if any supportable science was available, plaintiff’s bar would have already made this a high-profile target.”

Editor: While some biotech cases have failed the test of patentability before the courts, such as the case of Mayo v. Prometheus, what standard has been set forth for a biotech process to pass the test for patentability?

Vernon: There is no specified bright-line test for determining if a biotech process is patentable. But what the U.S. Patent and Trademark Office has done is to issue some new examination guidelines with respect to the Mayo decision that help examiners figure out whether a biotech process is patent eligible. Specifically, the guidelines look to see if the biotech process (i.e., a process incorporating a law of nature) also includes at least one additional element or step. That additional element needs to be significant and not just a mental or correlation step. If a biotech process patent claim includes this significant additional step, there still needs to be a determination if the process is novel and non-obvious over the prior art. So while this might not be a bright-line test to help us figure out whether a biotech process is patentable, it at least gives us some direction about what the examiners are looking for in the patent claims.

Editor: What effect do you think the new America Invents Act will have in encouraging biotech companies to file early in the first stages of product development? Might that not run the risk that the courts could deny patentability as in the Ariad case where functional results of a process were described rather than the specific invention?

Vernon: The AIA goes into effect next month. What companies, especially biotech companies, need to do is file early. Companies need to submit applications supported by their research to include both a written description and enablement of the invention. Companies will need to be more focused on making sure that they are not only inventing in a timely manner but are also involving their patent counsel in planned and well-thought-out experiments to make sure that the supporting information is available in a timely fashion for patenting.

Editor: Have there been any recent cases relating to biotechnology or nanotechnology that our readers should be informed about?

Vernon: The Supreme Court will hear oral arguments in April in the Myriad case. This case involves the BRCA gene, the breast cancer gene – and the issue is whether isolating a portion of a gene is patentable. While I am not a biotechnologist, I think this case will also impact nanotechnology as a whole. Applying for a patent on a portion of a gene is not too far distant from applying for a patent on a nanoparticle of a material that already exists but which has different properties from the original, larger-counterpart material. Would this nanosize material be patentable? This will be an important case to see what guidance the Supreme Court delivers this coming term.

Editor: Is there anything else you’d like to add?

Vernon: I think the next couple of years for nanotech will be very interesting. As I mentioned, I did my PhD thesis in the nanotechnology area a few years ago. My studies, like those of many other students, were funded in part with government grants. There is a great deal of government money being poured into nanotechnology. In the next ten years we will start seeing more and more of this research being commercialized and adopted into our lives. To keep current of developments, readers can visit www.nano.gov.

The Metropolitan Corporate Counsel
The Leading Resource For Corporate Counsel

As a leading publication in the corporate counsel community, MCC offers unique editorial content covering legal, regulatory, legislative and business developments, featuring original articles and interviews from experts at prestigious law firms, bar associations, accounting firms and legal service providers, as well as educators, business executives and high-level state, national and international officials.

 

Genesis Nanotech News: Latest Updates


QDLED 08_Bulovic_QDs_inLiquidSolutionsGenesis Nanotech: Latest News & Updates in Nanotechnology

U of Maryland Researchers Discover New synthesis Method: Could Impact the Futures of Nanostructures, Clean Energy

 

 

New Patent Issued to Samsung for Quantum Dot Organic Light Emitting Device (QDLED)

 

 

Simpler process to grow germanium nanowires could improve lithium ion batteries

 

 

Nanotechnology will leapfrog development.|Hiru News Official Web Site|Sri Lanka

IBM Solar Dish Does Double Duty


IBM%20parabolic%20dish

IBM Researchers build solar concentrator that generates electricity and enough heat for desalination or cooling.

Cooling a supercomputer can provide clues on how to make solar power cheap, says IBM.

IBM Research today detailed a prototype solar dish that uses a water-cooling technology it developed for its high-end computers (see “Hot Water Helps Super-Efficient Supercomputer Keep Its Cool”). The solar concentrator uses low-cost components and produces both electricity and heat, which could be used for desalination or to run an air conditioner.

IBM%20parabolic%20dish

Researchers envision giant concentrators, built with low-cost materials, that produce electricity and heat for use in desalination or cooling. Credit: IBM Research.

The work, funded by $2.4 million grant from the Swiss Commission for Technology and Innovation, is being done by IBM Research, the Swiss company Airlight Energy, and Swiss researchers. Since this is outside IBM’s main business, it’s not clear how the technology would be commercialized. But the high-concentration photovoltaic thermal (HCPVT) system promises to be cost-effective, according to IBM, and the design offers some insights into how to use concentrating solar power for both heat and electricity.

Typically, parabolic dishes concentrate sunlight to produce heat, which can be transfered to another machine or used to drive a Stirling engine that makes electricity (see “Running a Marine Unit on Solar and Diesel”). With this device, IBM and its partners used a solar concentrator dish to shine light on a thin array of highly efficient triple-junction solar cells, which produce electricity from sunlight. By concentrating the light 2,000 times onto hundreds of one-centimeter-square cells, IBM projects, a full-scale concentrator could provide 25 kilowatts of power.

In this design, the engineers hope to both boost the output of the solar cells and make use of the heat produced by the concentrator. Borrowing its liquid-cooling technology for servers, IBM built a cooling system with pipes only a few microns off the photovoltaic cells to circulate water and carry away the heat. More than 50 percent of the waste heat is recovered. “Instead of just throwing away the heat, we’re using the waste heat for processes such as desalination or absorption cooling,” says Bruno Michel, manager, advanced thermal packaging at IBM Research.

Researchers expect they can keep the cost down with a tracking system made out of concrete rather than metal. Instead of mirrored glass on the concentrator dish, they plan to use metal foils. They project the cost to be 10 cents per kilowatt-hour in desert regions that have the appropriate sunlight, such as the Sahara in northern Africa.

One of the primary challenges of such a device, apart from keeping costs down and optimizing efficiency, is finding a suitable application. The combined power and thermal generator only makes sense in places where the waste heat can be used at least during part of the day. The researchers envision it could be used in sunny locations without adequate fresh water reserves or, potentially, in remote tourist resorts on islands. In those cases, the system would need to be easy to operate and reliable.

Researchers Unveil New Solar Cell: Carbon Nanotubes that Convert Sunlight into MORE Power


CNT Solar 1-researchersuA team of researchers with members from several research facilities in the U.S. has unveiled a new type of solar cell based on single walled carbon nanotubes (SWCNTs). In their paper published in the journal Nano Letters, the team claims they have overcome limitations with such technology resulting in a solar cell that is two times as good at converting sunlight into power as other SWCNT based cells.

Scientists would like to use carbon nanotubes in solar cells because it would mean lighter panels, lower costs and easier to make products. They’ve been hampered, however, by the limited amount of power that such cells are able to generate. In this new effort the research team claims they’ve overcome the limitations of prior generations of SWCNTs by adding more chiralities to the nanotubes. Chiralities describe the way atoms are arranged in their hexagonal patterns—different patterns allow for absorbing different portions of the . Most prior efforts have used just one. This new team has added what they call polychiral SWCNTs to their cells which allows for capturing much more of the solar spectrum—most notably, in the near infrared, which other don’t make use of at all.

CNT Solar 1-researchersu

The researchers also added an ability to control the interface between the underlying hole-transport layer and the active photovoltaic layer, allowing the electron and hole pair (excitons) to recombine more efficiently. Taken together the two improvements serve to allow for both higher current and voltage, resulting in record high power conversion efficiency. They report that The National Renewable Energy Laboratory has already certified (by verifying) the performance claimed by the team. But the team isn’t done just yet. They want to improve the even more and may do so by testing new materials not used in any other cell.

Scientists would like to use carbon nanotubes in solar cells because it would mean lighter panels, lower costs and easier to make products. They’ve been hampered, however, by the limited amount of power that such cells are able to generate. In this new effort the research team claims they’ve overcome the limitations of prior generations of SWCNTs by adding more chiralities to the nanotubes. Chiralities describe the way atoms are arranged in their hexagonal patterns—different patterns allow for absorbing different portions of the . Most prior efforts have used just one. This new team has added what they call polychiral SWCNTs to their cells which allows for capturing much more of the solar spectrum—most notably, in the near infrared, which other don’t make use of at all.

The researchers also added an ability to control the interface between the underlying hole-transport layer and the active photovoltaic layer, allowing the electron and hole pair (excitons) to recombine more efficiently. Taken together the two improvements serve to allow for both higher current and voltage, resulting in record high power conversion efficiency. They report that The National Renewable Energy Laboratory has already certified (by verifying) the performance claimed by the team. But the team isn’t done just yet. They want to improve the even more and may do so by testing new materials not used in any other cell.

While it could be awhile before a product is made for sale based on what the team has wrought, their research might cause others in the field to take notice, which could conceivably result in a resurgence of interest in carbon based in general—interest has lagged in recent years as researchers began to doubt they could make them both useful and profitable. Hopefully so, because it would mean less expensive (and lighter) that produce as much power as conventional panels or even more—leading perhaps to a major move from greenhouse gas emitting coal fired to something much cleaner.

Explore further: Inexpensive flexible fiber perovskite solar cells

More information: Polychiral Semiconducting Carbon Nanotube–Fullerene Solar Cells, Nano Lett., Article ASAP, DOI: 10.1021/nl5027452

Abstract
Single-walled carbon nanotubes (SWCNTs) have highly desirable attributes for solution-processable thin-film photovoltaics (TFPVs), such as broadband absorption, high carrier mobility, and environmental stability. However, previous TFPVs incorporating photoactive SWCNTs have utilized architectures that have limited current, voltage, and ultimately power conversion efficiency (PCE). Here, we report a solar cell geometry that maximizes photocurrent using polychiral SWCNTs while retaining high photovoltage, leading to record-high efficiency SWCNT–fullerene solar cells with average NREL certified and champion PCEs of 2.5% and 3.1%, respectively. Moreover, these cells show significant absorption in the near-infrared portion of the solar spectrum that is currently inaccessible by many leading TFPV technologies.

 

 

Efficient Triple-Junction Polymer Solar Cell Design Sets New Record


Triple Junc SC id36745_1. Copyright © Nanowerk

Organic solar cells are conventionally made from two materials: a donor and an acceptor, which facilitates an efficient charge separation. For the acceptor, the most commonly used molecule is one of the blue absorbing fullerenes. This leaves the absorption spectrum of the donor material responsible to cover as much as possible of the solar spectrum. But most organic semiconductors only have a small optical bandwidth.

Consequently, solar cells based on such materials only catch a small part of the solar spectrum. This problem can be overcome with a properly designed stacked or tandem configuration, in which several organic materials are tuned so that each absorbs a separate part of the spectrum, thereby increasing the efficiency of the overall device. High bandgap semiconductor materials are used to absorb the short wavelength radiation, with longer wavelength parts transmitted to subsequent semiconductors.

In this context, researchers have set great hopes in the development of multi-junction solar cells, hoping to substantially exceed the performance of single-junction organic photovoltaics. In theory, a solar cell with an infinite number of junctions could obtain a maximum power conversion efficiency (PCE) of nearly 87% under highly concentrated sun light.

The challenge is to develop a semiconductor material system that can attain a wide range of bandgaps and be grown with high crystalline quality. New research coming out of the Yang Yang lab at the University of California, Los Angeles (UCLA), one of the leading labs for organic tandem solar cell research, presents an efficient design for a triple-junction organic tandem solar cell featuring a configuration of bandgap energies designed to maximize the tandem photocurrent output.

The key innovation in this study, reported in the July 14, 2014 online edition of Advanced Materials (“An Efficient Triple-Junction Polymer Solar Cell Having a Power Conversion Efficiency Exceeding 11%”), is the demonstration of organic materials being able to mimic the record-setting efficiency of triple-junction structures in III-V solar cells. III-V based solar cells constructed with the industry-standard GaInP/GaInAs/Ge technology have achieved the highest energy conversion efficiencies of all solar cells, with the current record exceeding 40%.

“In III–V multijunction solar cells, the optimal arrangement for a high-current-output triple-junction tandem cell features one wide-bandgap absorber (2.0–1.85 eV), one medium-bandgap absorber (1.4–1.2 eV), and one low-bandgap absorber (1.0–0.7 eV)”, Chun-Chao Chen, a graduate student in Yang’s lab and first author of the paper, explains to Nanowerk. “This optimal design rule cannot be applied directly to organic solar cells, however, because of the lack of efficient donor materials having bandgaps as low as 1 eV. Therefore, we set out to determine a practical combination of bandgap energies for triple junctions to develop an efficient organic tandem solar cell structure.”

 

 

Layer stacks of a triple-junction tandem solar cell

Schematic representation of the complete device structure: Layer stacks of the triple-junction tandem solar cell in the inverted architecture. (Reprinted with permission by Wiley-VCH Verlag)

For their design, the team used three materials with different energy bandgaps (1.9, 1.58, and 1.4 eV) as electron donors, blended with fullerene derivatives. With this arrangement of bandgap energies, they fabricated a highly efficient triple-junction tandem solar cell having a PCE of 11% – exceeding the record efficiency of a double-junction tandem solar cell, previously demonstrated by Yang’s group as well.

Energy levels of various materials for solar cells

 

Energy levels of the materials investigated in this study. Values for ITO, ZnO, and WO3 were measured using ultraviolet photoelectron spectroscopy (UPS); other values were taken from the literature. (Reprinted with permission by Wiley-VCH Verlag)

 

The specific problem in triple-junction solar cells is the complicated optical interference effect between each subcell included in the tandem. “When there are two junctions in tandem, the optical effect is easy to resolve,” say the UCLA researchers. “However, when it comes to triple junctions, you can not use trial and error to find out the optimal layer thickness for absorption for each subcell.”

To solve this issue, and in order to understand how each subcell works and how much current it can deliver, the team carried out in-depth and detailed optical simulations for each subcell. Benefiting from this tool, they came up with a simple and effective structure for connecting the subcells in tandem solar cells. This interconnecting structure, made of WO3/PEDOT:PSS/ZnO, is completely solution processed, thus keeping the orthogonal processing advantage of organic solar cells unchanged – regardless of how many junctions are added.

According to the UCLA team, “this design significantly strengthens our faith in tandem structure for organic solar cell.” They also points out that one of the outcomes of this study is the message that innovations in device architecture can potentially push the efficiencies of organic solar cell technology into the realm of inorganic photovoltaics.

The team is confident that their experience and knowledge gained from designing tandem solar cells can be transferred to other photovoltaic technologies – e.g. hybrid solar cells; perovskite solar cell; CIGS solar cells. Last year, for instance, they have shown that tandem structures can be combined with existing semitransparent solar cell design can result in a doubling of efficiency (read more: “Transparent film could coat windows, smartphone screens with energy-harvesting material“).

Read more: Efficient triple-junction polymer solar cell design sets new record http://www.nanowerk.com/spotlight/spotid=36745.php#ixzz39Ya0Onsn

Genesis Nanotech Headlines Are Out!


Organ on a chip organx250Genesis Nanotech Headlines Are Out! Read All About It!

https://paper.li/GenesisNanoTech/1354215819#!headlines

Visit Our Website: www.genesisnanotech.com

Visit/ Post on Our Blog: https://genesisnanotech.wordpress.com

 

SUBCOMMITTE EXAMINES BREAKTHROUGH NANOTECHNOLOGY OPPORTUNITIES FOR AMERICA

Chairman Terry: “Nanotech is a true science race between the nations, and we should be encouraging the transition from research breakthroughs to commercial development.”

WASHINGTON, DCThe Subcommittee on Commerce, Manufacturing, and Trade, chaired by Rep. Lee Terry (R-NE), today held a hearing on:

“Nanotechnology: Understanding How Small Solutions Drive Big Innovation.”

 

 

electron-tomography

“Great Things from Small Things!” … We Couldn’t Agree More!

 

Magnolia Solar Is Using Nanotechnology to Develop High-Efficiency Thin Film Solar Cells


QDOT images 6Magnolia Solar Corporation announced that it is pioneering the application of nanotechnology for both flexible CIGS and III-V solar cells in order to boost performance and lower costs. Magnolia Solar has developednanostructured optical coatings that can minimize reflection losses and enhance light trapping when applied to the surface of either CIGS or III-V solar cells. 

Magnolia Solar is also developing the technology to apply novel nanostructured designs to the absorber layer of high-performance III-V and CIGS solar cells in order to reduce recombination losses and increase the capture of low-energy photons.

Dr. Roger Welser, Magnolia Solar Chief Technical Officer (CTO), further stated, “Photovoltaic (PV) devices can provide a mobile source of electrical power for a wide variety of applications in both space and terrestrial environments. Many of these mobile and portable power applications can directly benefit from the development of flexible, lightweight, high-efficiency solar cells. Emerging technical approaches for achieving flexible photovoltaic power include the growth of copper indium gallium diselenide (CIGS) cells on flexible substrates and the epitaxial liftoff (ELO) of III-V devices onto thin metal film.”

Large Solar panels

Dr. Yash R. Puri, Executive Vice-President of Magnolia Solar Corporation, attended the Intersolar Energy Conference in San Francisco (July 6-10) to explore commercialization of the patent pending nanostructure-based coating technology for enhanced power output from solar panels. Dr. Puri stated, “This conference provides a forum to speak with leaders from many potential partner companies to explore commercialization of our technology to further enhance the power output of the solar panels.”

Dr. Ashok K. Sood, President and CEO of Magnolia Solar Corporation stated, “We are delighted to work very closely with the newly merged SUNY College of Nanoscale Science and Engineering (CNSE) / SUNY Institute of Technology (SUNYIT) institution, and our office in the Albany NanoTech complex allows our technical staff to work very closely with top researchers at the CNSE/SUNYIT facilities which have directly led to innovative patent pending designs using nanotechnology. This is helping us to meet our goals of high-efficiency thin film solar cells.”

“In support of Governor Andrew M. Cuomo’s clean energy-based vision for New York State and in furtherance of his NY-SUN initiative, we are thrilled that New York is fast becoming the epicenter for solar power research, development, and commercialization, as companies like Magnolia Solar continue to leverage SUNY CNSE/SUNYIT’s state-of-the-art, statewide resources that are providing a unique, cost-effective platform for the development of next-generation technologies,” said Dr. Pradeep Haldar, Vice President of Entrepreneurship Innovation and Clean Energy Programs at the newly merged SUNY CNSE/SUNYIT institution; Director of the SUNY CNSE/SUNYIT Energy and Environmental Technology Applications Center (E2TAC); Executive Director of New Energy New York (NENY); and Chief Operating and Technology Officer of the U.S. Photovoltaic Manufacturing Consortium (PVMC).
About Magnolia Solar Corporation
Based in Albany, NY and Woburn MA, Magnolia Solar was founded in 2008 to develop and commercialize revolutionary flexible thin-film solar cell technologies that employ nanostructured materials and designs. Both higher current and higher voltage outputs are expected from thin-film solar cells that combine Magnolia’s exclusive material structures with advanced optical coatings. Magnolia’s patent pending technology has the ability to capture a larger part of the solar spectrum to enable high efficiency solar cells and incorporates a unique nanostructure-based antireflection coating technology to further increase solar cell efficiency, thereby reducing the cost per watt. The company is targeting a variety of civilian and defense applications for its photovoltaic solar cells. Magnolia’s solar cell technology can be used to generate power for existing electrical grids and is particularly well-suited for distributed and portable power generation applications. http://www.MagnoliaSolar.com
Source: Magnolia Solar (press release)

 

Breakthrough Method (Discovery) for Characterizing Hot Carriers Could Hold the Key to Future Solar Cell Efficiencies


XBD200209-00526-02.PSDOne of the major road blocks to the design and development of new, more efficient solar cells may have been cleared. Researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab) have developed the first ab initio method – meaning a theoretical model free of adjustable or empirical parameters – for characterizing the properties of “hot carriers” in semiconductors. Hot carriers are electrical charge carriers – electrons and holes – with significantly higher energy than charge carriers at thermal equilibrium.

“Hot carrier thermalization is a major source of efficiency loss in solar cells, but because of the sub-picosecond time scale and complex physics involved, characterization of hot carriers has long been a challenge even for the simplest materials,” says Steven Louie, a theoretical physicist and senior faculty scientist with Berkeley Lab’s Materials Sciences Division (MSD). “Our work is the first ab initio calculation of the key quantities of interest for hot carriers – lifetime, which tells us how long it takes for hot carriers to lose energy, and the mean free path, which tells us how far the hot carriers can travel before losing their energy.”

XBD200209-00526-02.PSD

A new and better way to study “hot” carriers in semiconductors, a major source of efficiency loss in solar cells, has been developed by scientists at Berkeley Lab. (Photo by Roy Kaltschmidt)

All previous theoretical methods for computing these values required empirical parameters extracted from transport or optical measurements of high quality samples, a requirement that among the notable semiconductor materials has only been achieved for silicon and gallium arsenide. The ab initio method developed by Louie and Jeff Neaton, Director of the Molecular Foundry, a U.S. Department of Energy (DOE) Nanoscience User Facility hosted at Berkeley Lab, working with Marco Bernardi, Derek Vigil-Fowler and Johannes Lischner, requires no experimental parameters other than the structure of the material.

(From left) Steve Louie, Marco Bernardi, Jeff Neaton and Johannes Lischner developed the first ab initio method for characterizing hot carriers in semiconductors. (Photo by Roy Kaltschmidt)

“This means that we can study hot carriers in a variety of surfaces, nanostructures, and materials, such as inorganic and organic crystals, without relying on existing experiments,” says Neaton. “We can even study materials that have not yet been synthesized. Since we can access structures that are ideal and defect-free with our methods, we can predict intrinsic lifetimes and mean free paths that are hard to extract from experiments due to the presence of impurities and defects in real samples. We can also use our model to directly evaluate the influence of defects and impurities.”

Neaton, like Louie, is a senior MSD faculty scientist with the University of California (UC) Berkeley. Neaton also holds an appointment with the Kavli Institute for Energy Nanosciences. They are the corresponding authors of a paper in Physical Review Letters describing this work titled “Ab Initio Study of Hot Carriers in the First Picosecond after Sunlight Absorption in Silicon.” Bernardi is the lead author of the paper, and Vigil-Fowler the primary coauthor.

Single-junction solar cells based on crystalline silicon are rapidly approaching the theoretical limit of their efficiency, which is approximately 30-percent. This means that if a silicon-based solar cell collects 1,000 Watts per square meter of energy, the most electricity it can generate is 300 Watts per square meter. Hot carriers are crucial to enhancing solar cell  efficiency, since their thermalization results in the loss of as much as a third of the absorbed solar energy in silicon, and similar values in other semiconductors. However, the properties of hot carriers in complex materials for photovoltaic and other modern optoelectronic applications are still poorly understood.

“Our study was aimed at providing useful data for hot carrier dynamics in silicon with application in solar cells,” says Bernardi. “In this study we provide calculations from first principles that describe the two key loss mechanisms, induced by electrons and phonons, respectively, with state-of-the-art accuracy and within the frameworks of density functional and many-body perturbation theories.”

When the research team applied their method to study the relaxation time and mean free path of hot carriers in silicon, they found that thermalization under solar illumination is completed within 350 femtoseconds, and is dominated by phonon emission from hot carriers, a process that becomes progressively slower as the hot carriers lose energy and relax toward the band edges. This modeling result was in excellent agreement with the results of pump-probe experiments. While the model was only tested on silicon in this study, the researchers are confident it will be equally successful with other materials.

“We believe our approach is highly valuable to experimental groups studying hot carriers in the context of solar cells and other renewable energy technologies as it can be used to compute the lifetime and mean free path of hot carriers with specific energies, momenta, and crystallographic directions with unprecedented resolution,” Bernardi says. “As we expand our study of hot carriers to a range of crystalline materials and nanostructures, we believe that our data will provide unique microscopic insight to guide new experiments on hot carriers in semiconductors.”

This research was supported by the DOE Office of Science and the National Science Foundation and made use of the Molecular Foundry, as well as computational resources of the National Energy Research Scientific Computing Center (NERSC), which is also supported by the DOE Office of Science.

Additional Information

For more about the research of Steven Louie go here

For more about the research of Jeff Neaton go here

For more about the Molecular Foundry go here

For more about NERSC go here

For more about the Kavli Institute for Energy Nanosciences go here

– See more at: http://newscenter.lbl.gov/2014/07/17/first-ab-initio-method-for-characterizing-hot-carriers/#sthash.wY178h9s.dpuf

NANOTECHNOLOGY – On the Horizon and in the Far Future: Video


 

 

 

What is Nanotechnology?

 
A basic definition: Nanotechnology is the engineering of functional systems at the molecular scale. This covers both current work and concepts that are more advanced.

 

 
In its original sense, ‘nanotechnology’ refers to the projected ability to construct items from the bottom up, using techniques and tools being developed today to make complete, high performance products.

Nanotechnology (sometimes shortened to “nanotech”) is the manipulation of matter on an atomic and molecular scale. The earliest, widespread description of nanotechnology referred to the particular technological goal of precisely manipulating atoms and molecules for fabrication of macroscale products, also now referred to as molecular nanotechnology.

A more generalized description of nanotechnology was subsequently established by the National Nanotechnology Initiative, which defines nanotechnology as the manipulation of matter with at least one dimension sized from 1 to 100 nanometers. This definition reflects the fact that quantum mechanical effects are important at this quantum-realm scale, and so the definition shifted from a particular technological goal to a research category inclusive of all types of research and technologies that deal with the special properties of matter that occur below the given size threshold.

It is therefore common to see the plural form “nanotechnologies” as well as “nanoscale technologies” to refer to the broad range of research and applications whose common trait is size. Because of the variety of potential applications (including industrial and military), governments have invested billions of dollars in nanotechnology research.

Through its National Nanotechnology Initiative, the USA has invested 3.7 billion dollars. The European Union has invested 1.2 billion and Japan 750 million dollars