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“This is the first study to use pressure to control this stability, and it really opens up a lot of possibilities,” Yu Lin, researcher at the Stanford Institute for Materials and Energy Sciences (SIMES), said in a statement.

“Now that we’ve found this optimal way to prepare the material, there’s potential for scaling it up for industrial production, and for using this same approach to manipulate other perovskite phases,” Lin added.

The “black” phase, the one successfully stabilized by the scientists, of perovskite has intrigued scientists for years since it has been found to be extremely efficient in converting sunlight to electricity, making it the Holy Grail for solar panel technology.

Advanced optoelectronics require materials with newly engineered characteristics. Examples include a class of materials named metal-halide perovskites that have tremendous significance to form perovskite solar cells with photovoltaic efficiencies. Recent advances have also applied perovskite nanocrystals in light-emitting devices. The unusually efficient light emission of cesium lead-halide perovskite may be due to a unique excitonic fine structure made of three bright triplet states that minimally interact with a proximal dark singlet state. Excitons are electronic excitations responsible for the emissive properties of nanostructured semiconductors, where the lowest-energy excitonic state is expected to be long lived and hence poorly emitting (or ‘dark’).

In a new report now published in Science Advances, Albert Liu and a team of scientists in physics and chemistry at the University of Michigan, U.S., and Campinas State University, Brazil, used multidimensional coherent spectroscopy at cryogenic (ultra-cold) temperatures to study the fine structure without isolating the cube-shaped single nanocrystals. The work revealed coherences (wave properties relative to space and time) involving the triplet states of a cesium lead-iodide (CsPbI₃) nanocrystal ensemble. Based on the measurements of triplet and inter-triplet coherences, the team obtained a unique exciton fine structure level ordering composed of a dark state, energetically positioned within the bright triplet manifold.

Over the past few years, researchers have been trying to develop new designs for perovskite solar cells that could improve their performance, efficiency and stability over time. One possible way of achieving this is to combine 2-D and 3D halide perovskites in order to leverage the advantageous properties of these two different types of perovskites.

The two-dimensional crystal structure of 2-D halide perovskites is highly resistant to moisture; thus, it could help to increase the performance and durability of solar cells with a light-absorbing 3D halide perovskite layer. However, most of the strategies for combining 2-D and 3D halide perovskites proposed so far simply entail mixing these two materials together (e.g., mixing 2-D precursors with a solution-based 3D perovskite or reacting 2-D precursor solutions on top of a 3D perovskite layer).

Researchers at Seoul National University and Korea University have recently devised an alternative approach for creating solar cells that combine 2-D and 3D halide perovskites. This approach, outlined in a paper published in Nature Energy, could help to simultaneously improve both the efficiency and long-term stability of these cells.

InSight lander’s “mole” was unable to hammer through the Martian soil, and unusually dusty solar panels meant the robot was generating less power.

Scientists in China and Sweden have determined that a pinch of capsaicin, the chemical compound that gives chili peppers their spicy sting, may be a secret ingredient for more stable and efficient perovskite solar cells. The research, published January 13 in the journal Joule, determined that sprinkling capsaicin into the precursor of methylammonium lead triiodide (MAPbI₃) perovskite during the manufacturing process led to a greater abundance of electrons (instead of empty placeholders) to conduct current at the semiconductor’s surface. The addition resulted in polycrystalline MAPbI3 solar cells with the most efficient charge transport to date.

“In the future, green and sustainable forest-based biomaterial additive technology will be a clear trend in non-toxic lead-free perovskite materials,” says Qinye Bao, a senior author of the study from East China Normal University. “We hope this will eventually yield a fully green perovskite solar cell for a clean energy source.”

While metal halide perovskite semiconductors represent a promising component for state-of-the-art solar cell technologies, they are plagued by nonradiative recombination, an undesirable electron-level process that reduces efficiency and exacerbates heat losses. Bao and colleagues sought out a natural, forest-based, inexpensive additive to overcome this limitation and enhance solar cell performance.

All the clean technologies that we need to combat climate change – whether that’s wind turbines, solar panels or batteries, they’re all really, really mineral intensive.

Cornwall, 1864. A hot spring is discovered nearly 450m (1485ft) below ground in the Wheal Clifford, a copper mine just outside the mining town of Redruth. Glass bottles are immersed to their necks in its bubbling waters, carefully sealed and sent off for testing. The result is the discovery of so great a quantity of lithium – eight or 10 times as much per gallon as had been found in any hot spring previously analysed – that scientists suspect “it may prove of great commercial value”.

But 19th-Century England had little need for the element, and this 50C (122F) lithium-rich water continued steaming away in the dark for more than 150 years.

Continue reading “The new ‘gold rush’ for green lithium” »

Capturing energy from the Sun with solar panels is only half the story – that energy needs to be stored somewhere for later use. In the case of flow batteries, storage is relegated to vats of liquid. Now, an international team led by University of Wisconsin-Madison scientists has created a new version of these solar flow batteries that’s efficient and long-lasting.

To make the new device, the team combined several existing technologies. It’s a silicon/perovskite tandem solar cell, paired with a redox flow battery, which the team says will allow people to harvest and store renewable energy in one device. Not only is it efficient, but it should be inexpensive and simple enough to scale up for home use.

The energy-harvesting part of the equation combines the long-time industry-leading material – silicon – with a promising young upstart called perovskite. These tandem solar cells have proved better than either material alone, since the two materials capture different wavelengths of light.

Circa 2010

Unmanned aerial vehicles, or UAVs, are used in many applications to gather intelligence without risking human lives. These aircraft, however, have limited flight time because of their reconnaissance payload requirements coupled with their limited scale. A microwave-powered flight vehicle would be able to perform a reconnaissance mission continuously.

Using beamed microwave energy from a remote source on the ground, the airplane gathers energy using onboard antennas. A rectifying antenna, or rectenna, harvests power and rectifies it into a form usable by an onboard electric motor that drives the propeller, providing thrust. Using a rectenna array affixed to the underside of the aircraft, the power needed to maintain flight can be remotely transmitted.

Continue reading “Microwave Energy Transmission for Aircraft” »

Reactive molecules, such as free radicals, can be produced in the body after exposure to certain environments or substances and go on to cause cell damage. Antioxidants can minimize this damage by interacting with the radicals before they affect cells.

Led by Enrique Gomez, professor of chemical engineering and materials science and engineering, Penn State researchers have applied this concept to prevent imaging damage to conducting polymers that comprise soft electronic devices, such as organic solar cells, organic transistors, bioelectronic devices and flexible electronics. The researchers published their findings in Nature Communications today (Jan. 8).

According to Gomez, visualizing the structures of conducting polymers is crucial to further develop these materials and enable commercialization of soft electronic devices—but the actual imaging can cause damage that limits what researchers can see and understand.