Solar cell material can assist self-driving cars in the dark

Rui Zhang, postdoc fellow at IFM is one of the principle authors to the article published in Nature Photonics.
Photo Credit: Olov Planthaber

Material used in organic solar cells can also be used as light sensors in electronics. This is shown by researchers at Linköping University who have developed a type of sensor able to detect circularly polarized red light. Their study, published in Nature Photonics, paves the way for more reliable self-driving vehicles and other uses where night vision is important.

Some beetles with shiny wings, firefly larvae and colorful mantis shrimps reflect a particular kind of light known as circularly polarized light. This is due to microscopic structures in their shell that reflect the electromagnetic light waves in a particular way.

Circularly polarized light also has many technical uses, such as satellite communication, bioimaging and other sensing technologies. This is because circularly polarizing light carries a vast amount of information, due to the fact that the electromagnetic field around the light beam spirals either to the right or to the left.

Listening to atoms moving at the nanoscale

Professor Jan Seidel and his research lab have been using specialised techniques to listen to atoms moving.
Photo Credit: UNSW FLEET Centre.

Understanding how the phenomenon of ‘crackling noise’ occurs at the microscopic scale could have implications for new research in materials science and medicine.

Scientists from UNSW Sydney and the University of Cambridge have used novel methods to listen to the sounds of atoms moving under pressure – a phenomenon known as ‘crackling noise’.

These atomic movements occur in avalanches – they are similar to snow avalanches, but made of atoms – and follow very well-defined statistical rules.

Crackling noise can be observed every day, from crumpling paper and candy wrapping, to the crackling of your cereal, as well as in natural occurrences, such as earthquakes.

In a study recently published in Nature Communications, Professor Jan Seidel and his lab, from the School of Material Science and Engineering, were able to record the crackling noise of just a few hundred atoms, in experiments that lasted over eight hours.

Stacking Order and Strain Boosts Second-Harmonic Generation with 2D Janus Hetero-bilayers

Second-harmonic generation of 2D Janus MoSSe/MoS2 hetero-bilayers is optimized by stacking order and strain.
Image Credit: ©Nguyen Tuan Hung et al.

A group of researchers from Tohoku University, Massachusetts Institute of Technology (MIT), Rice University, Hanoi University of Science and Technology, Zhejiang University, and Oak Ridge National Laboratory have proposed a new mechanism to enhance short-wavelength light (100-300 nm) by second harmonic generation (SHG) in a two-dimensional (2D), thin material composed entirely of commonplace elements.

Since UV light with SHG plays an important role in semiconductor lithography equipment and medical applications that do not use fluorescent materials, this discovery has important implications for existing industries and all optical applications.

Copper-based catalysts efficiently turn carbon dioxide into methane

Soumyabrata Roy is a Rice University postdoctoral research associate in materials science and nanoengineering and the study’s lead author.
Photo Credit: Gustavo Raskosky/Rice University

Technologies for removing carbon from the atmosphere keep improving, but solutions for what to do with the carbon once it’s captured are harder to come by.

The lab of Rice University materials scientist Pulickel Ajayan and collaborators developed a way to wrest the carbon from carbon dioxide and affix it to hydrogen atoms, forming methane ⎯ a valuable fuel and industrial feedstock. According to the study published in Advanced Materials, the method relies on electrolysis and catalysts developed by grafting isolated copper atoms on two-dimensional polymer templates.

“Electricity-driven carbon dioxide conversion can produce a large array of industrial fuels and feedstocks via different pathways,” said Soumyabrata Roy, a research scientist in the Ajayan lab and the study’s lead author. “However, carbon dioxide-to-methane conversion involves an eight-step pathway that raises significant challenges for selective and energy-efficient methane production.

“Overcoming such issues can help close the artificial carbon cycle at meaningful scales, and the development of efficient and affordable catalysts is a key step toward achieving this goal.”

This salty gel could harvest water from desert air

MIT engineers have synthesized a superabsorbent material that can soak up a record amount of moisture from the air, even in desert-like conditions. Pictured are the hydrogel discs swollen in water.
 Photo Credit: Gustav Graeber and Carlos D. Díaz-Marín

MIT engineers have synthesized a superabsorbent material that can soak up a record amount of moisture from the air, even in desert-like conditions.

As the material absorbs water vapor, it can swell to make room for more moisture. Even in very dry conditions, with 30 percent relative humidity, the material can pull vapor from the air and hold in the moisture without leaking. The water could then be heated and condensed, then collected as ultrapure water.

The transparent, rubbery material is made from hydrogel, a naturally absorbent material that is also used in disposable diapers. The team enhanced the hydrogel’s absorbency by infusing it with lithium chloride — a type of salt that is known to be a powerful dessicant.

The researchers found they could infuse the hydrogel with more salt than was possible in previous studies. As a result, they observed that the salt-loaded gel absorbed and retained an unprecedented amount of moisture, across a range of humidity levels, including very dry conditions that have limited other material designs.

A New Magnetizable Shape Memory Alloy with Low Energy Loss, Even at Low Temperatures

Image Credit: Scientific Frontline

Shape memory alloys (SMA) remember their original shape and return to it after being heated. Similar to how a liquid transforms into a gas when boiled, SMAs undergo a phase transformation when heated or cooled. The phase transformation occurs with the movement of atoms, which is invisible to the naked eye.

SMAs are utilized in a diverse array of applications, including as actuators and sensors. However, the need to cool or heat SMAs means there is a delay in their phase transformation.

As a recently invented type of SMA, metamagnetic shape memory alloys (MMSMA) negate this limited response rate thanks to their ability to undergo phase transformation when exposed to an external magnetic field. Yet to date, MMSMAs have failed to solve another common problem with most SMAs: the fact that they lose a large amount of energy when phase transforming - something that worsens substantially in low temperatures.

High-performing alloy developed to help harness fusion energy

The research team demonstrated that minor additions of hafnium into the WTaCrV high entropy alloy lead to higher radiation resistance.
Photo credit: Courtesy of Los Alamos National Laboratory

A newly developed tungsten-based alloy that performs well in extreme environments similar to those in fusion reactor prototypes may help harness fusion energy.

“The new alloy shows promising resistance to irradiation resistance and stability under the high temperatures and extreme irradiation environments used to represent a fusion-reactor environment,” said Osman El Atwani, a staff scientist at Los Alamos National Laboratory. “The development of this alloy, and the agreement between modeling and experimentation that it represents, points the way toward the development of further useful alloys, an essential step in making fusion power generation more robust, cost-effective, economically predictable and attractive to investors.”

As fusion energy concepts move closer to the real world, solving the materials challenge is imperative. The encouraging results indicate that a design paradigm, as described by El Atwani and his collaborators, and high entropy alloys may be ready to play their role in harnessing the promise of fusion.

El Atwani was the principal investigator for the project, which involved several national and international institutions. Their results were published in Nature Communications.

Ba2LuAlO5: A New Proton Conductor for Next-Generation Fuel Cells

The discovery of Ba2LuAlO5 as a promising proton conductor paints a bright future for protonic ceramic fuel cells, report scientists from Tokyo Tech. Experiments show that this novel material has a remarkably high proton conductivity even without any additional chemical modifications, and molecular dynamics simulations reveal the underlying reasons. These new insights may pave the way to safer and more efficient energy technologies.

When talking about sustainability, the ways in which a society generates energy are some of the most important factors of consideration. Eager to eventually replace traditional energy sources such as coal and oil, scientists across the world are trying to develop environmentally friendly technologies that produce energy safely and more efficiently. Among them, fuel cells have been steadily gaining traction since the 1960s as a promising approach to producing electricity directly from electrochemical reactions.

However, typical fuel cells based on solid oxides have a notable drawback in that they operate at high temperatures, usually over 700 °C. That is why many scientists have focused on protonic ceramic fuel cells (PCFCs) instead. These cells use special ceramics that conduct protons (H+) instead of oxide anions (O2−). Thanks to a much lower operating temperature in the range of 300 to 600 °C, PCFCs can ensure a stable energy supply at a lower cost, compared to most other fuel cells. Unfortunately, only a few proton-conducting materials with reasonable performance are currently known, which is slowing down progress in this field.

Researchers develop new innovative heat storage material for enhanced energy efficiency

Beads which can store heat, which would otherwise be wasted, from various sources, including industrial operations and the summer sun. The new material has been made using alginate, an inexpensive, abundant and non-toxic seaweed derivative.
Photo Credit: Courtesy of Swansea University

Researchers from the SPECIFIC Innovation and Knowledge Centre and COATED M2A programme at Swansea University have collaborated with the University of Bath to make a groundbreaking advancement in thermal storage research, developing a new efficient material that is easily scalable and can be sized and shaped to fit multiple applications.

Published in the Journal of Materials Science, the material has been made using alginate, an inexpensive, abundant and non-toxic seaweed derivative.

The process starts with the dissolving of sodium alginate in water. Following this, expanded graphite is added, and a method of gelation is chosen:

• The first method is achieved by transferring the solution into a mold for freezing. After being kept at - 20°C for over two hours, beads are formed and transferred to a saturated calcium chloride solution.

• The second uses a drop-cast technique, with the mixture being dropped into thermochemical calcium salt, causing gelation on contact.

• Once sufficient salt diffusion has occurred, the synthesized beads are filtered and dried at 120°C.

Physicists discover an exotic material made of bosons

 Two stacked lattices with one slightly offset create a new pattern called a moiré
Photo Credit Matt Perko

Take a lattice — a flat section of a grid of uniform cells, like a window screen or a honeycomb — and lay another, similar lattice above it. But instead of trying to line up the edges or the cells of both lattices, give the top grid a twist so that you can see portions of the lower one through it. This new, third pattern is a moiré, and it’s between this type of overlapping arrangement of lattices of tungsten diselenide and tungsten disulfide where UC Santa Barbara physicists found some interesting material behaviors.

“We discovered a new state of matter — a bosonic correlated insulator,” said Richen Xiong, a graduate student researcher in the group of UCSB condensed matter physicist Chenhao Jin, and the lead author of a paper in the journal Science. According to Xiong, Jin and collaborators from UCSB, Arizona State University and the National Institute for Materials Science in Japan, this is the first time such a material      has been created in a “real” (as opposed to synthetic) matter system. The unique material is a highly ordered crystal of bosonic particles called excitons.

“Conventionally, people have spent most of their efforts to understand what happens when you put many fermions together,” Jin said. “The main thrust of our work is that we basically made a new material out of interacting bosons.”

PSI researchers use extreme UV light to produce tiny structures for information technology.

The PSI researchers involved at the XIL-II beamline of the SLS. From left to right: Yasin Ekinci, Gabriel Aeppli, Matthias Muntwiler, Procopios Christou Constantinou, Dimitrios Kazazis, Prajith Karadan
Photo Credit: Paul Scherrer Institute/Mahir Dzambegovic

Researchers at PSI have refined a process known as photolithography, which can further advance miniaturization in information technology.

In many areas of information technology, the trend towards ever more compact microchips continues unabated. This is mainly because production processes make it possible to achieve ever smaller structures, so that the same number of information-processing components takes up less and less space. Fitting more components into less space increases the performance and lowers the price of the microchips used in smartphones, smartwatches, game consoles, televisions, Internet servers and industrial applications.

A research group led by Dimitrios Kazazis and Yasin Ekinci at the Laboratory for X-ray Nanoscience and Technologies at the Paul Scherrer Institute PSI, in collaboration with researchers from University College London (UCL) in the UK, has now succeeded in making important progress towards further miniaturization in the IT industry. The scientists have demonstrated that photolithography – the method of patterning widely used in the mass production of microchips – works even when no photosensitive layer has been applied to the silicon.

'Charge Density Wave' Linked to Atomic Distortions in Would-be Superconductor

This image shows the positions of atoms (blue spheres) that make up the crystal lattice of a copper-oxide superconductor, superimposed on a map of electronic charge distribution (yellow is high charge density, dark spots are low) in charge-ordered states. Normally, the atoms can vibrate side-to-side (shadows represent average locations when vibrating). But when cooled to the point where the ladder-like charge density wave appears, the atomic positions shift along the "rungs" and the vibrations cease, locking the atoms in place. Understanding these charge-ordered states may help scientists unlock other interactions that trigger superconductivity at lower temperatures.
Illustration Credit: Courtesy of Brookhaven National Laboratory

Precision measurements reveal connection between electron density and atomic arrangements in charge-ordered states of a superconducting copper-oxide material

What makes some materials carry current with no resistance? Scientists are trying to unravel the complex characteristics. Harnessing this property, known as superconductivity, could lead to perfectly efficient power lines, ultrafast computers, and a range of energy-saving advances. Understanding these materials when they aren’t superconducting is a key part of the quest to unlock that potential.

“To solve the problem, we need to understand the many phases of these materials,” said Kazuhiro Fujita, a physicist in the Condensed Matter Physics & Materials Science Department of the U.S. Department of Energy’s Brookhaven National Laboratory. In a new study just published in Physical Review X, Fujita and his colleagues sought to find an explanation for an oddity observed in a phase that coexists with the superconducting phase of a copper-oxide superconductor.

Study reveals new ways for exotic quasiparticles to “relax”

By sandwiching bits of perovskite between two mirrors and stimulating them with laser beams, researchers were able to directly control the spin state of quasiparticles known as exciton-polariton pairs, which are hybrids of light and matter.
Illustration Credit: Courtesy of the researchers
(CC BY-NC-ND 3.0)

New findings from a team of researchers at MIT and elsewhere could help pave the way for new kinds of devices that efficiently bridge the gap between matter and light. These might include computer chips that eliminate inefficiencies inherent in today’s versions, and qubits, the basic building blocks for quantum computers, that could operate at room temperature instead of the ultracold conditions needed by most such devices.

The new work, based on sandwiching tiny flakes of a material called perovskite in between two precisely spaced reflective surfaces, is detailed in the journal Nature Communications, in a paper by MIT recent graduate Madeleine Laitz PhD ’22, postdoc Dane deQuilettes, MIT professors Vladimir Bulovic, Moungi Bawendi and Keith Nelson, and seven others.

By creating these perovskite sandwiches and stimulating them with laser beams, the researchers were able to directly control the momentum of certain “quasiparticles” within the system. Known as exciton-polariton pairs, these quasiparticles are hybrids of light and matter. Being able to control this property could ultimately make it possible to read and write data to devices based on this phenomenon.

With new experimental method, researchers probe spin structure in 2D materials for first time

In the study, researchers describe what they believe to be the first measurement showing direct interaction between electrons spinning in a 2D material and photons coming from microwave radiation.
 Graphic Credit: Jia Li, an assistant professor of physics at Brown.

For two decades, physicists have tried to directly manipulate the spin of electrons in 2D materials like graphene. Doing so could spark key advances in the burgeoning world of 2D electronics, a field where super-fast, small and flexible electronic devices carry out computations based on quantum mechanics.

Standing in the way is that the typical way in which scientists measure the spin of electrons — an essential behavior that gives everything in the physical universe its structure — usually doesn’t work in 2D materials. This makes it incredibly difficult to fully understand the materials and propel forward technological advances based on them. But a team of scientists led by Brown University researchers believe they now have a way around this longstanding challenge. They describe their solution in a new study published in Nature Physics.

In the study, the team — which also include scientists from the Center for Integrated Nanotechnologies at Sandia National Laboratories, and the University of Innsbruck — describe what they believe to be the first measurement showing direct interaction between electrons spinning in a 2D material and photons coming from microwave radiation. Called a coupling, the absorption of microwave photons by electrons establishes a novel experimental technique for directly studying the properties of how electrons spin in these 2D quantum materials — one that could serve as a foundation for developing computational and communicational technologies based on those materials, according to the researchers.

Beyond Moore’s Law: Innovations in solid-state physics include ultra-thin ‘two-dimensional’ materials and more

From left to right: Kaustav Banerjee and Arnab Pal
Photo Credit: Lilli McKinney

In the ceaseless pursuit of energy-efficient computing, new devices designed at UC Santa Barbara show promise for enhancements in information processing and data storage.

Researchers in the lab of Kaustav Banerjee, a professor of electrical and computer engineering, have published a new paper describing several of these devices, “Quantum-engineered devices based on 2D materials for next-generation information processing and storage,” in the journal Advanced Materials. Arnab Pal, who recently received his doctorate, is the lead author.

Each device is intended to address challenges associated with conventional computing in a new way. All four operate at very low voltages and are characterized as being low leakage, as opposed to the conventional metal-oxide semiconductor field-effect transistors (MOSFETs) found in smartphones that drain power even when turned off. But because they are based on processing steps similar to those used to make MOSFETs, the new devices could be produced at scale using existing industry-standard manufacturing processes for semiconductors.

The most promising of the two information-processing devices, according to Banerjee, is the spin-based field-effect transistor, or spin-FET, which takes advantage of the magnetic moment — or spin — of the electrons that power the device. In this case, the materials belong to the transition metal dichalcogenide group of compounds, which are based on transition metals. 

Discovering Hidden Order in Disordered Crystals New Material Analysis Method Combining Resonant X-Ray Diffraction and Solid-State NMR

Researchers at Tokyo Tech have discovered hidden chemical order of the Mo and Nb atoms in disordered Ba7Nb4MoO20, by combining state-of-the-art techniques, including resonant X-ray diffraction and solid-state nuclear magnetic resonance. This study provides valuable insights into how a material's properties, such as ionic conduction, can be heavily influenced by its hidden chemical order. These results would stimulate significant advances in materials science and engineering.

Determining the precise structure of a crystalline solid is a challenging endeavor. Materials properties such as ion conduction and chemical stability, are heavily influenced by the chemical (occupational) order and disorder. However, the techniques that scientists typically use to elucidate unknown crystal structures suffer from serious limitations.

For instance, X-ray and neutron diffraction methods are powerful techniques to reveal the atomic positions and arrangement in the crystal lattice. However, they may not be adequate for distinguishing different atomic species with similar X-ray scattering factors and similar neutron scattering lengths.

Versatile, High-Speed, and Efficient Crystal Actuation with Photothermally Resonated Natural Vibrations

Mechanically responsive molecular crystals are extremely useful in soft robotics, which requires a versatile actuation technology. Crystals driven by the photothermal effect are particularly promising for achieving high-speed actuation. However, the response (bending) observed in these crystals is usually small. Now, scientists from Japan address this issue by inducing large resonated natural vibrations in anisole crystals with UV light illumination at the natural vibration frequency of the crystal.

Every material possesses a unique natural vibration frequency such that when an external periodic force is applied to this material close to this frequency, the vibrations are greatly amplified. In the parlance of physics, this phenomenon is known as "resonance." Resonance is ubiquitous in our daily life, and, depending on the context, could be deemed desirable or undesirable. For instance, musical instruments like the guitar relies on resonance for sound amplification. On the other hand, buildings and bridges are more likely to collapse under an earthquake if the ground vibration frequency matches their natural frequency.

Interestingly, natural vibration has not received much attention in material actuation, which relies on the action of mechanically responsive crystals. Versatile actuation technologies are highly desirable in the field of soft robotics. Although crystal actuation based on processes like photoisomerization and phase transitions have been widely studied, these processes lack versatility since they require specific crystals to work. One way to improve versatility is by employing photothermal crystals, which show bending due to light-induced heating. While promising for achieving high-speed actuation, the bending angle is usually small (<0.5°), making the actuation inefficient.

Super-charged textile sets trends

The fabric becomes conductive when coated with with a special 'breathable' metallic layer.
Photo Credit: Flinders University

Scientists from around the world have developed a simple metallic coating treatment for clothing or wearable textiles which can repair itself, repel bacteria from the wearer and even monitor a person’s electrocardiogram (ECG) heart signals. 

Researchers from North Carolina State University, Flinders University and South Korea say the conductive circuits created by liquid metal (LM) particles can transform wearable electronics and open doors for further development of human-machine interfaces, including soft robotics and health monitoring systems.  

The ‘breathable’ electronic textiles have special connectivity powers to ‘autonomously heal’ itself even when cut, says the US team led by international expert in the field, Professor Michael Dickey. 

When the coated textiles are pressed with significant force, the particles merge into a conductive path, which enables the creation of circuits that can maintain conductivity when stretched. 

Researchers discover new self-assembled crystal structures

 Conceptual image showcasing several interaction potential shapes, represented by stems, that will lead to the self-assembly of new low-coordinated crystal structures, represented by flowers. 
Image Credit: Hillary Pan

Using a targeted computational approach, researchers in the Department of Materials Science and Engineering at Cornell have found more than 20 new self-assembled crystal structures, none of which had been observed previously.

The research, published in the journal ACS Nano under the title “Targeted Discovery of Low-Coordinated Crystal Structures via Tunable Particle Interactions,” is authored by Ph.D. student Hillary Pan and her advisor Julia Dshemuchadse, assistant professor of materials science and engineering.

“Essentially we were trying to figure out what kinds of new crystal structure configurations we can self-assemble in simulation,” Pan said. “The most exciting thing was that we found new structures that weren’t previously listed in any crystal structure database; these particles are actually assembling into something that nobody had ever seen before.”

The team conducted a targeted search for previously unknown low-coordinated assemblies within a vast parameter space spanned by particles interacting via isotropic pair potentials, the paper states. “Low-coordinated structures have anisotropic local environments, meaning that the geometries are highly directional, so it’s incredible that we’re able to see such a variety of these types of structures using purely non-directional interactions,” said Pan.

Scientists Develop Effective Silicon Surface Processing Technology

The technology will be useful in the creation of solar cells, as well as in biomedicine, chemistry, and IT.
 Photo Credit: Ilya Safarov

A team of scientists from Ekaterinburg (UrFU), Moscow, and St. Petersburg has developed a new technology for processing silicon wafers. It is a hybrid chemical and laser texturing, in which the wafer is treated with a femtosecond laser beam after chemical exposure to various reagents. Pre-chemical etching allows for five times faster laser treatment and improves light absorption over a broad spectral range. The technology will be useful in making solar cells. It could also be used in biomedicine for highly sensitive sensors for DNA analysis and detection of viruses and bacteria. It is also used in chemistry and in information and communication technologies. A description of the new technology has been published in the journal Materials.

"Currently, the formation of light-absorbing micro-reliefs on the surface of silicon wafers is achieved by a chemical process that is relatively inexpensive and used on an industrial scale. However, after chemical treatment, the wafers have a significant reflection coefficient, which reduces the efficiency of solar cells. An alternative method is laser treatment of the wafers. It reduces the reflection, but requires a significant amount of time using a femtosecond laser. Our proposed laser treatment after chemical etching reduces the processing time by a factor of five. At the same time, the reflection coefficient of wafers processed by the hybrid method is 7-10% lower than after chemical treatment," says Vladimir Shur, Director of the Ural Multiple Access Center "Modern Nanotechnologies" of the UrFU.