Energy Breakthrough Uses Sun to Create Solar Energy Materials

In a recent advance in solar energy, researchers have discovered a way to tap the sun not only as a source of power, but also to directly produce the solar energy materials that make this possible.

 

This breakthrough by chemical engineers at Oregon State University could soon reduce the cost of solar energy, speed production processes, use environmentally benign materials, and make the sun almost a “one-stop shop” that produces both the materials for solar devices and the eternal energy to power them.

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Revolutionary Solar Cells Double as Lasers

Revolutionary solar cells double as lasers

Commercial silicon-based solar cells - such as those seen on the roofs of houses across the country - operate at about 20% efficiency for converting the Sun’s rays into electrical energy. It’s taken over 20 years to achieve that rate of efficiency.

A relatively new type of solar cell based on a perovskite material - named for scientist Lev Perovski, who first discovered materials with this structure in the Ural Mountains in the 19th century - was recently pioneered by an Oxford research team led by Professor Henry Snaith. 

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A Molecular Ballet under the X-ray Laser

An international team of researchers has used the world’s most powerful X-ray laser to take snapshots of free molecules. 

The research team headed by Prof. Jochen Küpper of the Hamburg Center for Free-Electron Laser Science (CFEL) choreographed a kind of molecular ballet in the X-ray beam. 

With this work, the researchers have cleared important hurdles on the way to X-ray images of individual molecules, as they explain in the scientific journal Physical Review Letters. 

CFEL is a cooperation of DESY, the University of Hamburg, and the Max Planck Society.

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The molecules (green stream) enter the test chamber with random orientation and are forced to all take up the same pose by an optical laser (red). A bright X-ray flash (blue) produces a diffraction image (upper right) that contains structural information about the molecule. Credit: Stephan Stern/CFEL

 

Gold and Silica Nanostars Imitate the Two Faces of the God Janus

Researchers from the Basque centre CIC biomaGUNE and the University of Antwerp (Belgium) have designed nanoparticles with one half formed of gold branches and the other of silicon oxide. 

They are a kind of Janus particle, so-called in honour of the Roman god with two faces, which could be used in phototherapy in the future to treat tumours.

In Roman mythology, Janus was the god of gates, doors, beginnings and transitions between the past and the future. In fact, the first month of the year, January (from the Latin, ianuarĭus), bears his name. 

This deity was characterised by his profile of two faces, something which has inspired scientists, when naming their chemical designs with two clearly distinct components.

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Two examples of nanostars with one silicon oxide face (bluish) and another with golden branches (yellow). / Credit: Liz-Marzán et al.

Researchers Harness Sun’s Energy During Day for Use at Night

Solar energy has long been used as a clean alternative to fossil fuels such as coal and oil, but it could only be harnessed during the day when the sun’s rays were strongest. Now researchers led by Tom Meyer at the Energy Frontier Research Center at the University of North Carolina at Chapel Hill have built a system that converts the sun’s energy not into electricity but hydrogen fuel and stores it for later use, allowing us to power our devices long after the sun goes down.

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Targeted Synthesis of Natural Products With Light

Photoreactions are driven by light energy and are vital to the synthesis of many natural substances. Since many of these substances are also useful as active medical agents, chemists try to produce them synthetically. But in most cases only one of the possible products has the right spatial structure to make it effective. Researchers at the Technische Universitaet Muenchen (TUM) have now developed a methodology for one of these photoreactions that allows them to produce only the specific molecular variant desired.

 

The bulky Lewis acid (above) shields one side of the substrate (bottom) pushing the photoreaction in to the direction of the desired product. - Graphics: Richard Brimioulle / TUM

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Laser Treatments Yield Smoother Metal Surfaces

Ever since the Bronze Age, metals have been cast in different shapes for different applications. Smooth surfaces that are resistant to corrosion are crucial for many of the present-day uses of cast metals, ranging from bio-implants to automotive parts. Yingchun Guan, from the A*STAR Singapore Institute of Manufacturing Technology (SIMTech) and her co-workers have shown how different laser-processing methods improve metal surfaces and protect them against corrosion1.
Laser processing involves scanning a high-intensity laser beam multiple times across the surface of a metal. Each scan by the laser beam ‘writes’ a track in the surface, which partially melts the metal. Consecutive tracks can overlap — the degree to which affects how well the melting caused by these tracks will smooth the surface of the metal. The scanning speed can also affect the surface melt.

Optical microscope cross-sections of the alloy surface show that increases in laser beam overlap during processing reduces the number of small cracks (top left, 25% overlap; top right, 50%; bottom left, 75%; and bottom right, 90%). (Credit: Copyright Elsevier 2013)

 

 Credit: The Agency for Science, Technology and Research (A*STAR),

Bright, Laser-Based Lighting Devices

As a modern culture, we crave artificial white lights -- the brighter the better, and ideally using less energy than ever before. To meet the ever-escalating demand for more lighting in more places and to improve the bulbs used in sports stadiums, car headlights and street lamps, scientists are scrambling to create better light-emitting diodes (LEDs) -- solid state lighting devices that are more energy efficient than conventional incandescent or fluorescent light sources. 

Just one thing stands in the way: "droop," the term for a scientific problem related to LEDs currently in use. Droop refers to the fact that LED efficiency falls as operating currents rise, making the lights too hot to power in large-scale applications. Many scientists are working on new methods for modifying LEDs and making progress toward cooler, bigger and brighter bulbs. 

Photograph of bright white light (right) achieved using lasers in combination with phosphors next to an image of the phosphor with no illumination. (Credit: K.Denault/UCSB)

 Credit: aipadvances

Wagon-Wheel Pasta Shape for Better LED Lights

One problem in developing more efficient organic LED light bulbs and displays for TVs and phones is that much of the light is polarized in one direction and thus trapped within the light-emitting diode, or LED. University of Utah physicists believe they have solved the problem by creating a new organic molecule that is shaped like rotelle – wagon-wheel pasta – rather than spaghetti.

The rotelle-shaped molecule – known as a “pi-conjugated spoked-wheel macrocycle” – acts the opposite of polarizing sunglasses, which screen out glare reflected off water and other surfaces and allow only direct sunlight to enter the eyes.

Images of molecules for light-emitting diodes on the left are compared with similar shaped pasta on the right. The upper left electron microscope image shows spaghetti-shaped organic polymers now used for organic light-emitting diodes, or OLEDs. The lower left image shows new molecules -- created by scientists at the University of Utah and two German universities -- that are shaped like wagon-wheel or rotelle pasta and emit light more efficiently than the spaghetti-shape polymers. (Credit: Molecule images by Stefan Jester, University of Bonn. Pasta images courtesy Wikimedia Commons. Wagon wheel pasta image has been released into the public domain by its author, Fazalmajid at the English project. Spaghetti image has been licensed under the Creative Commons Attribution-Share Alike 2.0 Generic license)

 Credit: University of Utah

Basic Photochemistry

Photochemistry is the underlying mechanism for all of photobiology. When a molecule absorbs a photon of light, its electronic structure changes, and it reacts differently with other molecules. For more click here.

Jablonski diagram

Courtesy: Emeritus Professor Kendric C. Smith, Stanford University School of Medicine