Nanotechnology to Provide Better Solar Cells, Optical Devices

While we work for the eventual development of a nanotechnology that transforms human life via atomically precise manufacturing, the partial control of the configuration of atoms in important materials that is afforded by current nanotechnology promises great near-term advantages.

 

A decade ago, Foresight focused on progress in nanotechnology to meet six major challenges faced by humanity. Although we haven’t said as much the past several years about these challenges (except for #3, Improving Health and Longevity), recent progress promises great contributions to the other challenges as well.

Challenge #1, Providing Renewable Clean Energy, appears soon to profit from advances in controlling the atomic configuration of gallium arsenide nanowires. Patrick Cox’s Tech Digest reports on “Building a Better Solar Cell One Atom at a Time“. Citing work by researchers at the Norwegian University of Science and Technology working with IBM engineers to grow gallium arsenide nanowires on graphene, he concludes:

… With a better understanding of how, atom by atom, a panel’s composition could be manipulated to achieve maximum output, solar-panel technology of the future promises to become lighter and more portable, as well as easier to manufacture and maintain. …

A hat tip to ScienceDaily for providing more details by reprinting news published by the Norwegian University of Science and Technology “Better Solar Cells, Better LED Light And Vast Optical Possibilities“:

Changes at the atom level in nanowires offer vast possibilities for improvement of solar cells and LED light. NTNU-researchers have discovered that by tuning a small strain on single nanowires they can become more effective in LEDs and solar cells.

 

NTNU researchers Dheeraj Dasa and Helge Weman have, in cooperation with IBM, discovered that gallium arsenide can be tuned with a small strain to function efficiently as a single light-emitting diode or a photodetector. This is facilitated by the special hexagonal crystal structure, referred to as wurtzite, which the NTNU researchers have succeeded in growing in the MBE lab at NTNU. The results were published in Nature Communications [abstract].

… By altering the crystal structure in a substance, i.e. changing the positions of the atoms, the substance can gain entirely new properties. The NTNU researchers discovered how to alter the crystal structure in nanowires made of gallium arsenide and other semiconductors.

With that, the foundation was laid for more efficient solar cells and LEDs.

“Our discovery was that we could manipulate the structure, atom by atom. We were able to manipulate the atoms and alter the crystal structure during the growth of the nanowires. This opened up for vast new possibilities. We were among the first in the world who were able to create a new gallium arsenide material with a different crystal structure,” says Helge Weman at the Department of Electronics and Telecommunications.

… The next big news came in 2012. At that point, the researchers had managed to make semiconductor nanowires grow on the super-material graphene. Graphene is the thinnest and strongest material ever made. This discovery was described as a revolution in solar cell and LED component development.

… The research group has received a lot of international attention for the graphene method. Helge Weman and his NTNU co-founders Bjørn-Ove Fimland and Dong-Chul Kim have established the company CrayoNano AS, working with a patented invention that grows semiconductor nanowires on graphene. The method is called molecular beam epitaxy (MBE), and the hybrid material has good electric and optical properties.

“We are showing how to use graphene to make much more effective and flexible electronic products, initially solar cells and white light-emitting diodes (LED). The future holds much more advanced applications,” says Weman.

… The last couple of years the research group has, among other things, studied the unique hexagonal crystal structure in the GaAs nanowires.

“In cooperation with IBM, we have now discovered that if we stretch these nanowires, they function quite well as light-emitting diodes. Also, if we press the nanowires, they work quite well as photodetectors. This is facilitated by the hexagonal crystal structure, called wurtzite. It makes it easier for us to change the structure to optimise the optical effect for different applications.

“It also gives us a much better understanding, allowing us to design the nanowires with a built-in compressive stress, for example to make them more effective in a solar cell. This can for instance be used to develop different pressure sensors, or to harvest electric energy when the nanowires are bent,” Weman explains.

Because of this new ability to manipulate the nanowires’ crystal structure, it is possible to create highly effective solar cells that produce a higher electric power. Also, the fact that CrayoNano now can grow nanowires on super-light, strong and flexible graphene, allows production of very flexible and lightweight solar cells.

The CrayoNano group will now also start growing gallium nitride nanowires for use in white light-emitting diodes.

“One of our objectives is to create gallium nitride nanowires in a newly installed MBE machine at NTNU to create light-emitting diodes with better optical properties — and grow them on graphene to make them flexible, lightweight and strong.”

This work illustrates beautifully the practical benefits from increasing ability to control the configuration of atoms in materials. This work uses currently available tools to control the atomic configuration of bulk materials. Atomically precise manufacturing, when it is developed, will allow specifying different atomic configurations to produce, if needed, nanometer scale complexity throughout a microscale or macroscale object to manufacture enormously complex systems of materials, devices, and molecular machines.
—James Lewis, PhD

Integrated Solar Energy: Generation-Conversion-Storage-Utilization: One System

Almost all strategies for solar energy harvest and solar energy storage that exist today are developed as independent technologies. For instance, a solar cell generates electricity from the absorption and conversion of sunlight, while the storage of the produced electricity has to be implemented with another set of energy utilization solutions such as batteries/supercapacitors and fuel cells.

 

Photoelectrochemical (PEC) conversion based on semiconductor materials is a highly important and promising approach for utilizing solar energy with minimal carbon emissions. Today, it is one of the most sustainable methods of producing hydrogen – when sun hits the PEC cell, the solar energy is absorbed and used for splitting water molecules into its components, hydrogen and oxygen.

One of the largest challenges facing PEC water splitting technologies – and other solar conversion techniques as well – is the selection and design of semiconductor photoelectrode materials/structures, due to multiple stringent requirements including photoelectrochemical stable, appropriate band gap size and band edge position, fast charge transfer and low recombination rates, and efficient hydrogen/oxygen evolution.

In addition, the waste of the oxidative energy in producing oxygen from water splitting, and the loss of electric energy when delivering electron flows into an external energy storage device, are two additional important factors that limit the efficient utilization of the solar energy.

With quite an ingenious solution, researchers have now demonstrated a hybrid, multifunctional material system that allows for simultaneous solar power generation (respectively hydrogen production), electrical energy storage, and chemical sensing. “The development of our work offers opportunities for direct converting the solar energy into two different forms of energy that can be directly utilized, i.e., hydrogen gas at the photocathode and supercapacitive energy at the photoanode,” Gengfeng Zheng, a professor of chemistry at Fudan University, tells Nanowerk. “Our system obtains a high pseudocapacitance of up to 455 F g-1 with repeating charging-discharging capability. More importantly, the NiO nanomaterials grown on the photoanode can further serve as an excellent glucose sensor using the stored electrochemical energy, with a high sensitivity up to 0.1 µM.”

As the team reports in the May 13, 2014 online edition of Nano Letters (“Fully Solar-Powered Photoelectrochemical Conversion for Simultaneous Energy Storage and Chemical Sensing”), this means that the fully solar-powered energy storage and utilization device also serves as a glucose sensor by directly utilizing solar energy for in situ glucose detection.

Schematic of the TiO2/NiO photoanode and the Si/Pt photocathode for the solar-powered PEC-pseudocapacitive system. (a) Structures of the materials and devices. (b) Solar-powered PEC-pseudocapacitive mechanism. (c) Energy diagram of the system. (Reprinted with permission from American Chemical Society)

With the materials for energy conversion, energy storage and energy utilization integrated together in the photoelectrodes, this device can directly utilize the solar energy input – i.e. just exposing the sensor to sunlight – to produce a chemical response to the glucose level in an aqueous solution. “Recently, there have been two very important developments in the fields of solar energy conversion and electrical energy storage,” Zheng explains the background for this work.

“First, a solution-grown TiO2/Ni(OH)2 nanocomposite has been reported to exhibit integrated solar hydrogen production and pseudocapacitive energy storage, in which the oxidative energy is stored by chemical conversion of Ni2+ into Ni3+ (“Integrated photoelectrochemical energy storage: solar hydrogen generation and supercapacitor”).” In this work, though, due to the relatively low conduction band minimum of TiO2, an external electrical field is necessary to drive the electron flow for the water reduction, which does not yet meet the goal of direct energy conversion and storage.

“Second” continues Zheng, “the recent substantial development of artificial photosynthesis approaches suggests that using two semiconductor light absorbers, with band diagrams configured as the ‘Z-scheme’, provides an effective approach to cover a larger part of solar spectrum for enhanced photoabsorption, as well as allows for efficient reduction and oxidation at each photoelectrode (see for instance: Light-Induced Charge Transport within a Single Asymmetric Nanowire and “A Fully Integrated Nanosystem of Semiconductor Nanowires for Direct Solar Water Splitting”).

Inspired by these two important developments, the team’s work was able to demonstrate the use of combined semiconductor materials and metal catalysts for efficient solar photoelectrochemical conversion and electrochemical energy storage/utilization. “Distinct from the previous report of electric field-biased device, our material system fully relies on the solar energy for charge carrier separation and transport, and provides selective targeting of glucose analytes in aqueous solution with high sensitivity,” Zheng points out. “our work is the first time that a photoelectrochemical conversion is coupled with pseudocapacitive energy storage, without the assistance of additional electrical bias voltage.

In addition, it is the first time that an electrochemical sensor is fully driven by solar energy, without any signal amplification methods.” This work has two specific potential applications. Firstly, the enhanced solar energy conversion integrated with direct energy storage suggests new device design/structures for efficient solar power utilization. Secondly, the direct use of solar energy for glucose sensing, without the need of any auxiliary instruments, offers a convenient point-of-care detection method that can be used widely at home or office, thus serving as a fast, sensitive diagnosis of diabetics and other diseases.

Zheng notes that it has been widely accepted that any single material cannot fulfill the goal of efficient solar energy utilization. “The future direction of this research field still requires the further development of new structure design and synthetic methods for realizing hybrid material and catalyst composites that can enhance their solar conversion and electrical energy storage efficiency,” he says. “One particular challenge is to find the material combination that offers the most optimal photoabsorption, band gap alignment to water and chemical targets of interest, charge transport, and surface chemical reaction kinetics.”

“The other particular challenge is to increase the material load and stability of the photoelectrode for large capacity, long cycling life devices, as well as using all earth-abundant materials for reducing the fabrication cost.” Zheng’s co-authors are Yongcheng Wang, Jing Tang, Zheng Peng, Yuhang Wang, Dingsi Jia, Biao Kong, Ahmed A. Elzatahry, and Dongyuan Zhao. This work was supported by the National Key Basic Research Program of China, the Natural Science Foundation of China, and the Deanship of Scientific Research of King Saud University.

Copyright © Nanowerk

Read more: An integrated solar-powered energy conversion-storage-utilization system http://www.nanowerk.com/spotlight/spotid=35933.php#ixzz34410bpjU
Follow us: @nanowerk on Twitter

New Nano-Supercapacitor Technology: U of Central Florida

One of the fundamental challenges of battery technology is that lithium-ion batteries — by far the best general option for energy storage currently in wide commercial use — are intrinsically bulky and heavy. A new research team at the University of Central Florida believes they can challenge that problem by turning copper wires into supercapacitors, then embedding those wires into the fabric of your clothing or the body of a device. In theory, they could also be embedded throughout the body of a car, significantly boosting total energy storage and freeing up space in the trunk.

 

According to nanotechnology researcher Jayan Thomas, his work on the concept involves first heating copper wire to create nano-whiskers — nanoscale-sized tendrils of metal that split off from the main wire. These are then protected by a sheath of naturally forming copper oxide (produced when the wire is heated in air). This turns the nanowhisker into an electrode. The entire structure is then wrapped in a plastic sheath, with a second set of nanowhiskers. The end result is a layered structure that looks like the feature image above — the copper wire in the center still conducts power, but the nanoscale structures store additional electricity as well.

Supercapacitor or battery?

Some write-ups are describing this as a type of battery, but the authors refer to it as a supercapacitor, and that designation appears to make more sense. The difference between supercapacitors and batteries, from a functional standpoint, is that batteries can store significantly more energy than a supercapacitor, but cannot release that energy nearly as quickly. Supercapacitors store less energy in total, but can discharge it nearly instantly. Supercapacitors tend to make poor batteries and vice versa, despite continuing research to find a way to blend the two.

The real question is how much energy can be feasibly stored in this type of copper wire and how effectively the nanostructures can be recharged without degrading. While the author talks of weight and bulk savings, copper is significantly heavier than metals like aluminum, and the extra shielding required will have its own weight. This ability to embed supercapacitor capability into virtually any surface could have a significant impact in some fields, but only if it winds up saving space or weight compared to existing methods. Efforts to incorporate traditional lithium-ion batteries into flexible cables have also been developed; LG demonstrated this type of structure two years ago.

How Thomas Edison Changed The World – Reactions

Published on Jun 2, 2014

Thomas Edison is hands-down one of the greatest inventors in history. He also had a love of chemistry that banished him to the basement as a kid. In this episode, we go behind the scenes at the Thomas Edison National Historical Park to see how Edison’s love of chemistry fueled his world-changing inventions.
Subscribe! http://bit.ly/ACSReactions

Edison Park is an amazing complex home to more than 400,000 artifacts (which we definitely weren’t allowed to touch) and is considered the template for modern labs everywhere.

For more info on Edison’s amazing chemical discoveries: http://www.acs.org/content/acs/en/edu…

 

Nanowires Boost Efficiency of Quantum Dot Solar Cells

Solar cells made from quantum dots could be low-cost, flexible, and easy to make. But the efficiency with which they convert light into electricity remains too low for practical use. Researchers at the Massachusetts Institute of Technology now show that incorporating nanowires into quantum dot solar cells increases the cells’ efficiency by 35%. 

 

 

Quantum dots are semiconductor nanocrystals that absorb different wavelengths of light depending on their size. Solar cells made from different-sized crystals should absorb light over a much wider range of colors than silicon devices. What’s more, because quantum dots are made in solution, they could be easily printed or painted onto flexible surfaces. Scientists have calculated that quantum dots could be used to make thin-film solar cells that could convert light to electricity with 15% efficiency, the same as commercial silicon devices.

The best-performing quantum dot solar cells consist of a lead sulfide quantum dot layer butted up against a zinc oxide or titanium dioxide layer. The quantum dots absorb light, and electrons created in the process travel to the metal oxide layer to reach the electrical circuit. The problem is that the quantum dot layer has to be thick enough to absorb light efficiently, but thin enough for the electrons to quickly traverse it.

The MIT researchers, led by electrical engineering and computer science professor Vladimir Bulovic, overcame that tradeoff by replacing the flat ZnO layer with an array of vertical zinc oxide nanowires. The nanowires penetrate the quantum dot layer, providing conductive paths for the electrons to follow out to the electrical circuit, says Joel Jean, a graduate student in Bulovic’s group. The researchers published their results in the journal Advanced Materials.   

The researchers start with glass substrates that are coated with indium tin oxide transparent electrodes. They deposit a ZnO layer on top and float the entire susbtrate upside down in an aqueous solution of zinc precursors. An array of aligned nanowires grows downwards from the ZnO layer. After about an hour, the researchers rinse the substrates. Finally, they deposit PbS quantum dots, which fill up the space between the nanowires, and top it off with a gold electrode.

The nanowires boost the output current of the devices by 50% and the efficiency by 35% over planar ZnO devices. The overall light-to-electricity conversion efficiency of the new devices is 4.9 percent, among the highest reported for ZnO-based quantum dot solar cells, Jean says.

The researchers believe the efficiency could be further enhanced by using thicker light-absorbing layers and longer nanowires, as well as by controlling the spacing between nanowires to better accommodate quantum dots.

The idea of using ZnO nanowires to increase efficiency in quantum dot solar cells is not new, but this is the first significant implementation of the concept, says Matthew Beard, a senior scientist at the National Renewable Energy Laboratory. “The observed efficiency boost is promising and significant,” he says. “The efficiencies for these types of solar cells are increasing rapidly and this work demonstrates that the improvements in efficiency will continue.”

A key advantage of the nanowire-quantum dot cells, says Jean, is that they could be made on large areas. “One of the main benefits of quantum dots is that they’re grown in and deposited from solution,” he says. “This translates to fabrication of large-area films, which is necessary for making solar panels. Zinc oxide nanowires are also grown in an aqueous solution process. Scalability should be one of the primary practical advantages of this type of solar cell.” 

Read the Abstract in Advanced Materials  here.

 

Can Organic Solar Cells Using Polymeric Materials and Fullerenes (Quantum Dots) be a Solution for Abundant & Cheap Solar Energy ?

 

Oldenburg, Germany | Posted on May 30th, 2014

Can Organic Solar Cells Using Polymeric Materials and Fullerenes (Quantum Dots) be a Solution for Abundant & Cheap Solar Energy?

Abstract

Photovoltaic cells directly convert sun light into electricity and hence are key technological devices to meet one of the challenges that mankind has to face in this century: a sustainable and clean production of renewable energy. Organic solar cells, using polymeric materials to capture sun light, have particularly favorable properties. They are low-cost, light-weight and flexible, and their color can be adapted by varying the material composition. Such solar cells typically consist of nanostructured blends of conjugated polymers (long chains of carbon atoms), acting as light absorbers, and fullerenes (nanoscale carbon soccer balls), acting as electron acceptors.

The primary and most elementary step in the light-to-current conversion process, the light-induced transfer of an electron from the polymer to the fullerene, occurs at such a staggering speed that it has previously proven difficult to follow it directly.

Now, a team of German and Italian researchers from Oldenburg, Modena and Milano reported the first real time movies of the light-to-current conversion process in an organic solar cell. In a report published in the May 30 issue of Science Magazine, the researchers show that the quantum-mechanical, wavelike nature of electrons and their coupling to the nuclei is of fundamental importance for the charge transfer in an organic photovoltaic device.

“Our initial results were actually very surprising”, says Christoph Lienau, a physics professor from the University of Oldenburg who led the research team. “When we used extremely short, femtosecond (1 billionth of a millionth of a second, i.e. 0.000000000000001 seconds) light pulses to illuminate the polymer layer in an organic cell, we found that the light pulses induced oscillatory, vibrational motion of the polymer molecules. Unexpectedly, however, we saw that also the fullerene molecules all started to vibrate synchronously.

We could not understand this without assuming that the electronic wave packets excited by the light pulses would coherently oscillate back and forth between the polymer and the fullerene.” All colleagues with whom the scientists discussed these initial results, obtained by PhD student Sarah Falke from Oldenburg in close collaboration with the team of Giulio Cerullo from Politecnico di Milano, leading experts in ultrafast spectroscopy, were skeptical.

“In such organic blends, the interface morphology between polymer and fullerene is very complex and the two moieties are not covalently bound”, says Lienau, “therefore one might not expect that vibronic coherence persists even at room temperature. We therefore asked Elisa Molinari and Carlo A. Rozzi, of the Istituto Nanoscienze of CNR and the University of Modena and Reggio Emilia, for help.”

A series of sophisticated quantum dynamics simulations, performed by Rozzi and colleagues, provided impressive movies of the evolution of the electronic cloud and of the atomic nuclei in this system, which are responsible of the oscillations found in experiments. “Our calculations indicate”, says Molinari, “that the coupling between electrons and nuclei is of crucial importance for the charge transfer efficiency. Tailoring this coupling by varying the device morphology and composition hence may be important for optimizing device efficiency”.

Will the new results immediately lead to better solar cells?

“Such ultrafast spectroscopic studies, and in particular their comparison with advanced theoretical modelling, provide impressive and most direct insight in the fundamental phenomena that initiate the organic photovoltaic process. They turn out to be very similar to the strategies developed by Nature in photosynthesis.”, says Lienau. “Recent studies indicate that quantum coherence apparently plays an important role in that case. Our new result provide evidence for similar phenomena in functional artificial photovoltaic devices: a conceptual advancement which could be used to guide the design of future artificial light-harvesting systems in an attempt to match the yet unrivalled efficiency of natural ones . “

####

Prof. Dr. Christoph Lienau
Carl von Ossietzky University Oldenburg
Institute of Physics
Ultrafast Nano-Optics

Prof. Dr. Elisa Molinari
Istituto Nanoscienze–Consiglio Nazionale delle Ricerche (CNR),

Copyright © Istituto Nanoscienze — CNR

 

 

 

 

“If You Want to Change the World … “

Naval Admiral William H. McRaven gave a commencement speech at his alma mater at the University of Texas at Austin worth reading, printing out and hanging on the inside of your front door.

 

No one has to be a Navy SEAL to get the most out of these 10 life lessons (life lesson listed first for ease of reading). Via Business Insider:

 

“If You Want to Change the World … “

 

#1. If you want to change the world, start off by making your bed.

 

“If you make your bed every morning you will have accomplished the first task of the day. It will give you a small sense of pride and it will encourage you to do another task and another and another. […]

.

If you can’t do the little things right, you will never do the big things right.”

 

#2. If you want to change the world, find someone to help you paddle.

 

“For the boat to make it to its destination, everyone must paddle.

.

You can’t change the world alone—you will need some help— and to truly get from your starting point to your destination takes friends, colleagues, the good will of strangers and a strong coxswain to guide them.”

 

#3. If you want to change the world, measure a person by the size of their heart, not the size of their flippers.

 

“The munchkin boat crew had one American Indian, one African American, one Polish American, one Greek American, one Italian American, and two tough kids from the mid-west.

.

They out paddled, out-ran, and out swam all the other boat crews. […]

.

But somehow these little guys, from every corner of the Nation and the world, always had the last laugh— swimming faster than everyone and reaching the shore long before the rest of us.

.

SEAL training was a great equalizer. Nothing mattered but your will to succeed. Not your color, not your ethnic background, not your education and not your social status.”

 

#4. If you want to change the world get over being a sugar cookie and keep moving forward.

 

“For failing the uniform inspection, the student had to run, fully clothed into the surfzone and then, wet from head to toe, roll around on the beach until every part of your body was covered with sand.

.

The effect was known as a ‘sugar cookie.’ You stayed in that uniform the rest of the day—cold, wet and sandy.

.

There were many a student who just couldn’t accept the fact that all their effort was in vain. That no matter how hard they tried to get the uniform right—it was unappreciated.

.

Those students didn’t make it through training. […]

.

Sometimes no matter how well you prepare or how well you perform you still end up as a sugar cookie.

.

It’s just the way life is sometimes.”

 

#5 But if you want to change the world, don’t be afraid of the circuses.

 

“A ‘circus’ was two hours of additional calisthenics—designed to wear you down, to break your spirit, to force you to quit.

.

No one wanted a circus.

.

A circus meant that for that day you didn’t measure up. A circus meant more fatigue—and more fatigue meant that the following day would be more difficult—and more circuses were likely.

.

.Life is filled with circuses.

.

You will fail. You will likely fail often. It will be painful. It will be discouraging. At times it will test you to your very core.”

 

#6. If you want to change the world sometimes you have to slide down the obstacle head first.

 

“But the most challenging obstacle was the slide for life. It had a three level 30 foot tower at one end and a one level tower at the other. In between was a 200-foot long rope.

.

You had to climb the three tiered tower and once at the top, you grabbed the rope, swung underneath the rope and pulled yourself hand over hand until you got to the other end.

.

The record seemed unbeatable, until one day, a student decided to go down the slide for life—head first.

.

Instead of swinging his body underneath the rope and inching his way down, he bravely mounted the TOP of the rope and thrust himself forward.

.

It was a dangerous move—seemingly foolish, and fraught with risk. Failure could mean injury and being dropped from the training.

.

Without hesitation—the student slid down the rope—perilously fast, instead of several minutes, it only took him half that time and by the end of the course he had broken the record.”

 

#7. So, if you want to change the world, don’t back down from the sharks.

 

“During the land warfare phase of training, the students are flown out to San Clemente Island which lies off the coast of San Diego.

.

The waters off San Clemente are a breeding ground for the great white sharks. To pass SEAL training there are a series of long swims that must be completed. One—is the night swim.

.

Before the swim the instructors joyfully brief the trainees on all the species of sharks that inhabit the waters off San Clemente.

.

They assure you, however, that no student has ever been eaten by a shark—at least not recently.

.

But, you are also taught that if a shark begins to circle your position—stand your ground. Do not swim away. Do not act afraid.

.

And if the shark, hungry for a midnight snack, darts towards you—then summons up all your strength and punch him in the snout and he will turn and swim away.

.

There are a lot of sharks in the world. If you hope to complete the swim you will have to deal with them.”

 

#8. If you want to change the world, you must be your very best in the darkest moment.

 

“To be successful in your mission, you have to swim under the ship and find the keel—the center line and the deepest part of the ship.

.

This is your objective. But the keel is also the darkest part of the ship—where you cannot see your hand in front of your face, where the noise from the ship’s machinery is deafening and where it is easy to get disoriented and fail.

.

Every SEAL knows that under the keel, at the darkest moment of the mission—is the time when you must be calm, composed—when all your tactical skills, your physical power and all your inner strength must be brought to bear.”

 

#9. So, if you want to change the world, start singing when you’re up to your neck in mud.

 

“The mud consumed each man till there was nothing visible but our heads. The instructors told us we could leave the mud if only five men would quit—just five men and we could get out of the oppressive cold.

.

Looking around the mud flat it was apparent that some students were about to give up. It was still over eight hours till the sun came up—eight more hours of bone chilling cold.

.

The chattering teeth and shivering moans of the trainees were so loud it was hard to hear anything and then, one voice began to echo through the night—one voice raised in song.

.

The song was terribly out of tune, but sung with great enthusiasm.

.

One voice became two and two became three and before long everyone in the class was singing. […]

.

The instructors threatened us with more time in the mud if we kept up the singing—but the singing persisted.

.

And somehow—the mud seemed a little warmer, the wind a little tamer and the dawn not so far away.

 

If I have learned anything in my time traveling the world, it is the power of hope. The power of one person—Washington, Lincoln, King, Mandela and even a young girl from Pakistan—Malala—one person can change the world by giving people hope.”

 

#10. If you want to change the world don’t ever, ever ring the bell.

 

Finally, in SEAL training there is a bell. A brass bell that hangs in the center of the compound for all the students to see.

.

All you have to do to quit—is ring the bell. Ring the bell and you no longer have to wake up at 5 o’clock. Ring the bell and you no longer have to do the freezing cold swims.

.

Ring the bell and you no longer have to do the runs, the obstacle course, the PT—and you no longer have to endure the hardships of training.

.

Just ring the bell.”

 

Of course, if you ring that bell, you can never accomplish your goal in life. When things seem hardest, that’s when you push hardest. That’s the only way you can stop being a “sugar cookie.”

 

Improved Performance and Stability in Quantum Dot Solar Cells through Band Alignment Engineering

Published online: 25 May 2014

Solution processing is a promising route for the realization of low-cost, large-area, flexible and lightweight photovoltaic devices with short energy payback time and high specific power.

 

 

 

However, solar cells based on solution-processed organic, inorganic and hybrid materials reported thus far generally suffer from poor air stability, require an inert-atmosphere processing environment or necessitate high-temperature processing¹, all of which increase manufacturing complexities and costs.

Simultaneously fulfilling the goals of high efficiency, low-temperature fabrication conditions and good atmospheric stability remains a major technical challenge, which may be addressed, as we demonstrate here, with the development of room-temperature solution-processed ZnO/PbS quantum dot solar cells.

By engineering the band alignment of the quantum dot layers through the use of different ligand treatments, a certified efficiency of 8.55% has been reached.

Furthermore, the performance of unencapsulated devices remains unchanged for over 150 days of storage in air. This material system introduces a new approach towards the goal of high-performance air-stable solar cells compatible with simple solution processes and deposition on flexible substrates.

 

At a glance

a, Device architectures. b, Representative J–V characteristics of devices with Au anodes under simulated AM1.5G irradiation (100 mW cm⁻²). The PbS-TBAI device consists of 12 layers of PbS-TBAI and the PbS-TBAI/PbS-EDT device consists o…

a, Energy levels with respect to vacuum for pure PbS-TBAI, pure PbS-EDT and PbS-TBAI films covered with different thicknesses of PbS-EDT layers. The Fermi levels (E_F, dashed line) and valence band edges (E_V, blue lines) were determined

a, Open circuit voltage (V_OC). b, Short-circuit current (J_SC). c, Fill factor (FF). d, Power conversion efficiency (PCE). Measurements were performed in a nitrogen-filled glovebox. Day 0 denotes measurements performed after anode evapo…

a, Evolution of photovoltaic parameters of PbS-TBAI (black) and PbS-TBAI/PbS-EDT (red) devices. Open symbols represent the average values and solid symbols represent the values for the best-performing device. b, Device performance of a…

Chia-Hao M. Chuang,^1,

• Patrick R. Brown,^2,
• Vladimir Bulović^3,
• & Moungi G. Bawendi^4, 
• Affiliations
• Contributions
• Corresponding author

Journal name: Nature Materials: Year published: (2014)

DOI: doi:10.1038/nmat3984

Received: 06 December 2013

Accepted: 15 April 2014

 

 

BASF Sees Nanotechnology as Innovation Driver in Numerous Applications

BASF increased spending on research and development to €1.8 billion (2012: €1.7 billion) in 2013. “In absolute terms, we lead the field in the chemical industry with our research and development expenditures,” said Dr. Andreas Kreimeyer, member of the Board of Executive Directors of BASF SE and Research Executive Director, at the Research Press Conference on the topic ”Nanotechnology: Small dimensions – great opportunities” in Ludwigshafen.

BASF has a workforce of around 10,650 employees working in international and interdisciplinary teams on around 3,000 research projects to find answers to the challenges of the future and secure sustainable profitable growth for the company.

The innovative strength of BASF is demonstrated once more by sales of new products introduced onto the market within the past five years: Last year these amounted to about €8 billion. In 2013 alone, the company launched more than 300 new products on the market. The patent portfolio also reflects the success of the company’s research activities. With 1,300 patents filed last year and about 151,000 registrations and intellectual property rights worldwide, BASF is at the top of the Patent Asset Index for the fifth time in succession.

New research laboratories in North America and Asia

In future, BASF is expecting strong impulses from the regions for its innovation pipeline. By 2020, 50% of its research activities are to be conducted outside Europe. In 2013, BASF came another step closer to this goal and increased the proportion of its research outside Europe to 28% (2012: 27%). To drive the globalization of research further forward, the company has, among other things, established six new laboratories at different locations in Asia and the United States. Moreover, for example in cooperation with highly innovative universities, BASF has founded the “California Research Alliance by BASF” (CARA) in California. Here, the main research focus is on the biosciences and new inorganic materials for the areas energy, electronics and renewable resources. In Asia, the company has, for example, joined forces with top-ranking universities from China, Japan and Korea to found the research initiative ”Network for Advanced Materials Open Research” (NAO). In this joint project, research is underway on materials for a wide range of applications, including products for the automotive, construction and water industries and for the wind energy sector.

BASF collaborates in a global network with more than 600 outstanding universities, research institutes and companies. “Interdisciplinary and international cooperations are a decisive element of BASF’s Know-how Verbund,” added Kreimeyer. Offering intelligent solutions for the challenges of the future based on new systems and functional materials requires not only interdisciplinary approaches but also the use of cross-sectional technologies like nanotechnology.

Nanotechnology – helping to develop solutions for the future

Nanotechnology is concerned with the development, manufacture and use of materials that have structures, particles, fibers or platelets smaller than 100 nanometers and so possess novel properties. Many innovations in areas such as automotive technology, energy, electronics or construction and medicine would not be possible without nanotechnology. BASF uses this technology to develop new solutions and improve existing products.

High-performance insulation materials

Nanopores provide the specific material characteristics in one of BASF’s new high-performance insulation material. Slentite™ is the first high-performance insulation panel based on polyurethane, which needs only half the space compared to traditional materials while offering the same insulation performance. Up to 90% of the volume of the organic aerogel consists of air-filled pores which have a diameter of only 50 to 100 nanometers. As a result, the air molecules’ freedom of movement is limited and the transfer of heat is reduced. The high-performance insulation material can be used, for example, in the construction sector for old and new buildings.

Microencapsulation

One BASF research field in which nanotechnology plays a key role focuses on the development of formulations of active components, especially on microencapsulation. Active substances are thereby enclosed with a wax, polymer or oil-based protective shell. This enables the actives to be used more specifically for the application concerned and function more effectively. The important factor here is the controlled release of the actives. Researchers at BASF have succeeded in designing the shell according to the application need, making it only a few nanometers thick or nanostructured. This allows control of the time and speed at which the active substances can be released at the desired target location.

A material that could contribute to the key technological progress of Organic Light Emitting Diodes (OLEDs), displays and even batteries and catalysts is graphene. It is closely related to graphite, which is used, for example, in pencil leads. Unlike graphite, graphene consists of only one layer of carbon atoms, making it less than one nanometer thin. This material is a very efficient electricity and heat conductor and is very stable but also elastic and flexible. Because it is so thin, the actually black material appears transparent. An international team of researchers is currently exploring the scientific basis and application potential of innovative carbon-based materials like graphene at the joint research and development platform of BASF and the Max Planck Institute for Polymer Research in Mainz, Germany. Color filters BASF’s new red color, Irgaphor® Red S 3621 CF, ensures an excellent image quality of liquid crystal displays (LCD). It is used in color filters for notebook, computer and television screens. The smaller the particles are, the more intense the brightness of screens becomes. BASF has succeeded in manufacturing its product with a particle size of less than 40 nanometers. The tiny particles enable considerably less scattering of light in the color filter. Compared to traditional color products, BASF’s new red doubles the contrast ratio of displays. This leads to a sharp, pure-colored, high-contrast and thus brilliant image.

Safely utilizing the potentials of nanotechnology

Accessing new technologies requires an objective assessment of both the opportunities and risks. In addition to the manufacture and development of nanomaterials, another research priority is the risk assessment of nanoparticles. For about ten years, BASF has therefore been pursuing safety research with nanomaterials. During this time the company has conducted more than 150 own toxicology and ecotoxicology studies and participated in approximately 30 different projects with external partners.

Open dialog for a common understanding

Innovation-friendly social and political conditions are decisive in allowing the potentials of nanotechnology to be utilized. “Public discussion is very important for us. We actively seek dialog, also with critical opinion leaders,” said Kreimeyer. For example, BASF has – as the first and so far only company in Germany – established a regularly held dialog forum focusing on nanotechnology. At these events, BASF employees conduct discussions with various representatives of environmental and consumer organizations, labor unions, scientific institutions and churches to improve understanding of current concerns, explain opportunities, answer questions and jointly identify constructive solutions.

About BASF

BASF is the world’s leading chemical company: The Chemical Company. Its portfolio ranges from chemicals, plastics, performance products and crop protection products to oil and gas. We combine economic success with environmental protection and social responsibility. Through science and innovation, we enable our customers in nearly every industry to meet the current and future needs of society. Our products and solutions contribute to conserving resources, ensuring nutrition and improving quality of life. We have summed up this contribution in our corporate purpose: We create chemistry for a sustainable future. BASF had sales of about €74 billion in 2013 and over 112,000 employees as of the end of the year. Further information on BASF is available on the Internet at http://www.basf.com.

Source: BASF (press release)

Read more: BASF Sees Nanotechnology as Innovation Driver in Numerous Applications http://www.nanowerk.com/nanotechnology-news/newsid=35755.php?utm_source=feedburner&utm_medium=twitter&utm_campaign=Feed%3A+nanowerk%2FagWB+%28Nanowerk+Nanotechnology+News%29#ixzz32wvktWxO

Algorithms are Becoming Key to Designing New Materials

From solar panels to batteries, algorithms are becoming key to designing new materials

 

 

 

 

 

Summary: Materials science is being transformed by algorithms, and computers are now selecting new material combinations to test in the lab.

In the future, materials that could make a super efficient solar panel or a breakthrough battery probably won’t be discovered by a smart human scientist. Like everything else in this world, computers and software are increasingly identifying the best combination of materials to deliver a desired result, and then human researchers are testing out those computers’ choices in the lab.

For University of Colorado professor Alex Zunger, that idea is a fundamental change in materials research. Zunger is the chief theorist at the Center for Inverse Design, and at the SunShot Summit last week he spoke about how “inverse design” — identifying specific properties that are desired in a material, then determining that material’s required atomic structure — could transform sectors like solar.

For decades, materials for new applications have been selected to be tested “rather casually,” said Zunger, based on “simple ideas,” or even “availability in the lab.” But now, thanks to sophisticated algorithms, scientists can use computer intelligence to make these choices.

Zunger is particularly interested in using inverse design and computer intelligence to figure out the optimal materials to use quantum dots for solar materials. Quantum dots are little pieces of semiconductor crystals — less than 10 nanometers — that are so small they have different properties and characteristics than larger semiconductor pieces. But so far, Zunger says, there hasn’t been an obvious winning combination for solar quantum dots.

Zunger isn’t the only one doing this. It’s actually a hot trend for some of the most cutting-edge materials startups out there.

For example, a startup called Pellion Technologies, which was spun out of MIT, developed advanced algorithms and computer modeling that enabled it to test out 10,000 potential cathode materials to fit with a magnesium anode for a battery. Now the startup is developing a magnesium battery, which could have a very high energy density, and if it works could be important for electric vehicles and grid storage.

A founder of Pellion, MIT professor Gerbrand Ceder, helped develop the Materials Genome Project at MIT, which is a program that uses computer modeling and virtual simulations to deliver innovation in materials. The Economist once described Ceder’s work with the Materials Genome Project as “a short cut” for discovering electrodes and the interactions of inorganic chemical compounds.

Other smart people are also working on this idea. Columbia University’s Institute for Data Sciences and Engineering spearheaded important work in the area, and professors Venkat Venkatasubramanian and Sanat Kumar recently published research on their work designing nanostructured materials with an inverse design framework and genetic algorithms.

While this trend might seem like yet another way that computers are replacing humans, it’s actually an example of ways that computers can leverage massive data sets (that humans can’t) to advance society and make life better — for humans. It’s similar to the way that automated vehicles will make driving more efficient, safer and more productive. Odds are that the material breakthroughs of the future will come from this combination of artificial intelligence and human intelligence.