Nav: Home

Science snapshots: New nitrides, artificial photosynthesis, and TMDC semiconductors

June 17, 2019

Groundbreaking Study Maps Out Paths to New Nitride Materials

Formed by elements combining with nitrogen, nitrides can possess unique properties with potential applications from semiconductors to industrial coatings. But before nitrides can be put to use, they first must be discovered - and the odds of finding them in nature are slim.

Now, your chances of discovering new nitrides just got better with a groundbreaking Nature Materials study led by Berkeley Lab in close collaboration with the National Renewable Energy Laboratory (NREL) and a number of other institutions.

The study features a large, interactive stability map of the ternary nitrides, highlighting nitride compositions where experimental discovery is promising in blue. So far, the map has yielded the prediction of 244 new stable ternary nitride compounds.

"For ancient explorers, sailing into the unknown was a very risky endeavor, and in the same way, exploration of new chemical spaces can also be risky," explained Wenhao Sun, lead author of the paper and staff scientist at Berkeley Lab. "If you don't find a new material where you are looking, it can be a big waste of time and effort. Our chemical map can help to guide the exploratory synthesis of nitrides, just as maps helped to guide explorers, allowing them to navigate better."

Read the full release from NREL here .

Here Comes the Sun: A New Framework for Artificial Photosynthesis

Scientists have long sought to mimic the process by which plants make their own fuel using sunlight, carbon dioxide, and water through artificial photosynthesis devices, but how exactly substances called catalysts work to generate renewable fuel remains a mystery.

Now, a PNAS study led by Berkeley Lab - and supported by state-of-the-art materials characterization at the Joint Center for Artificial Photosynthesis, powerful X-ray spectroscopy techniques at the Advanced Light Source, and superfast calculations performed at the National Energy Research Scientific Computing Center - has uncovered new insight into how to better control cobalt oxide, one of the most promising catalysts for artificial photosynthesis.

When molecules of cobalt oxide cubane, so named for its eight atoms forming a cube, are in solution, the catalytic units eventually collide into one another and react, and thus deactivate.

To hold the catalysts in place, and prevent these collisions, the researchers used a metal-organic framework as a scaffold. The technique is similar to how tetramanganese, a metal-oxygen catalyst in natural photosynthesis, protects itself from self-destruction by hiding in a protein pocket.

"Our study provides a clear, conceptual blueprint for engineering the next generation of energy-converting catalysts," said Don Tilley, senior faculty scientist in Berkeley Lab's Chemical Sciences Division (and a co-corresponding author of the study.

You Don't Have to Be Perfect for TMDCs to Shine Bright
By Theresa Duque

Atomically thin semiconductors known as TMDCs (transition metal dichalcogenides) could lead to devices that operate more efficiently than conventional semiconductors in light-emitting diodes, lasers, and solar cells. But these materials are hard to make without defects that dampen their performance.

Now, a study led by senior faculty scientist Ali Javey of Berkeley Lab - and published in the journal Science - has revealed that TMDCs' efficiency is diminished not by defects, but by the extra free electrons.

In a previous study, the researchers used chemical treatments to improve TMDCs' photoluminescence quantum yield, a ratio describing the amount of light generated by the material versus the amount of light absorbed. "But that's not ideal because the treatments are unstable in subsequent processing," said co-first author and graduate student researcher Shiekh Zia Uddin.

For the current study, the researchers discovered that when they applied an electrical voltage instead of a chemical treatment to TMDCs made of molybdenum disulfide and tungsten disulfide, the extra free electrons are removed from the material, resulting in a quantum yield of 100%.

"A quantum yield of 100% is unprecedented in inorganic TMDCs, said Der-Hsien Lien, postdoctoral researcher and co-first author. "This is an exciting result that shows it might be much easier and cheaper than previously thought to make useful optoelectronic devices from these materials."
Media contact: Theresa Duque,, 510-495-2418

DOE/Lawrence Berkeley National Laboratory

Related Semiconductors Articles:

New class of 'soft' semiconductors could transform HD displays
New research by Berkeley Lab scientists could help usher in a new generation of high-definition displays, optoelectronic devices, photodetectors, and more.
'Magic' alloy could spur next generation of solar cells
In what could be a major step forward for a new generation of solar cells called 'concentrator photovoltaics,' University of Michigan researchers have developed a new semiconductor alloy that can capture the near-infrared light located on the leading edge of the visible light spectrum.
Organic electronics: Semiconductors as decal stickers
No more error-prone evaporation deposition, drop casting or printing: Scientists at Ludwig-Maximilians-Universitaet (LMU) in Munich and FSU Jena have developed organic semiconductor nanosheets, which can easily be removed from a growth substrate and placed on other substrates.
Coffee-ring effect leads to crystallization control in semiconductors
KAUST researchers developed a method to control the orientation and properties of crystal regions within polycrystalline semiconductors.
UNIST engineers oxide semiconductor just single atom thick
A new study, affiliated with South Korea's Ulsan National Institute of Science and Technology, has introduced a new technique that efficiently isolates circulating tumor cells from whole blood at a liquid-liquid interface.
More Semiconductors News and Semiconductors Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#534 Bacteria are Coming for Your OJ
What makes breakfast, breakfast? Well, according to every movie and TV show we've ever seen, a big glass of orange juice is basically required. But our morning grapefruit might be in danger. Why? Citrus greening, a bacteria carried by a bug, has infected 90% of the citrus groves in Florida. It's coming for your OJ. We'll talk with University of Maryland plant virologist Anne Simon about ways to stop the citrus killer, and with science writer and journalist Maryn McKenna about why throwing antibiotics at the problem is probably not the solution. Related links: A Review of the Citrus Greening...