Connect with us

Solar Energy

Twisting, flexible crystals key to solar energy production

Published

on

Twisting, flexible crystals key to solar energy production

Researchers at Duke University have revealed long-hidden molecular dynamics that provide desirable properties for solar energy and heat energy applications to an exciting class of materials called halide perovskites.

A key contributor to how these materials create and transport electricity literally hinges on the way their atomic lattice twists and turns in a hinge-like fashion. The results will help materials scientists in their quest to tailor the chemical recipes of these materials for a wide range of applications in an environmentally friendly way.

The results appear online March 15 in the journal Nature Materials.

“There is a broad interest in halide perovskites for energy applications like photovoltaics, thermoelectrics, optoelectronic radiation detection and emission – the entire field is incredibly active,” said Olivier Delaire, associate professor of mechanical engineering and materials science at Duke. “While we understand that the softness of these materials is important to their electronic properties, nobody really knew how the atomic motions we’ve uncovered underpin these features.”

Perovskites are a class of materials that – with the right combination of elements – are grown into a crystalline structure that makes them particularly well-suited for energy applications. Their ability to absorb light and transfer its energy efficiently makes them a common target for researchers developing new types of solar cells, for example. They’re also soft, sort of like how solid gold can be easily dented, which gives them the ability to tolerate defects and avoid cracking when made into a thin film.

One size, however, does not fit all, as there is a wide range of potential recipes that can form a perovskite. Many of the simplest and most studied recipes include a halogen–such as chlorine, fluorine or bromine – giving them the name halide perovskites. In the crystalline structure of perovskites, these halides are the joints that tether adjoining octahedral crystal motifs together.

While researchers have known these pivot points are essential to creating a perovskite’s properties, nobody has been able to look at the way they allow the structures around them to dynamically twist, turn and bend without breaking, like a Jell-O mold being vigorously shaken.

“These structural motions are notoriously difficult to pin down experimentally. The technique of choice is neutron scattering, which comes with immense instrument and data analysis effort, and very few groups have the command over the technique that Olivier and his colleagues do,” said Volker Blum, professor of mechanical engineering and material science at Duke who does theoretical modeling of perovskites, but was not involved with this study. “This means that they are in a position to reveal the underpinnings of the materials properties in basic perovskites that are otherwise unreachable.”

In the study, Delaire and colleagues from Argonne National Laboratory, Oak Ridge National Laboratory, the National Institute of Science and Technology, and Northwestern University, reveal important molecular dynamics of the structurally simple, commonly researched halide perovskite (CsPbBr3) for the first time.

The researchers started with a large, centimeter-scale, single crystal of the halide perovskite, which is notoriously difficult to grow to such sizes – a major reason why this sort of dynamic study has not been achieved before now. They then barraged the crystal with neutrons at Oak Ridge National Laboratory and X-rays at Argonne National Laboratory. By measuring how the neutrons and X-rays bounced off the crystals over many angles and at different time intervals, the researchers teased out how its constituent atoms moved over time.

After confirming their interpretation of the measurements with computer simulations, the researchers discovered just how active the crystalline network actually is. Eight-sided octahedral motifs attached to one another through bromine atoms were caught twisting collectively in plate-like domains and constantly bending back and forth in a very fluid-like manner.

“Because of the way the atoms are arranged with octahedral motifs sharing bromine atoms as joints, they’re free to have these rotations and bends,” said Delaire. “But we discovered that these halide perovskites in particular are much more ‘floppy’ than some other recipes. Rather than immediately springing back into shape, they return very slowly, almost more like Jell-O or a liquid than a conventional solid crystal.”

Delaire explained that this free-spirited molecular dancing is important to understand many of the desirable properties of halide perovskites. Their ‘floppiness’ stops electrons from recombining into the holes the incoming photons knocked them out of, which helps them make a lot of electricity from sunlight. And it likely also makes it difficult for heat energy to travel across the crystalline structure, which allows them to create electricity from heat by having one side of the material be much hotter than the other.

Because the perovskite used in the study – CsPbBr3 – has one of the simplest recipes, yet already contains the structural features common to the broad family of these compounds, Delaire believes that these findings likely apply to a large range of halide perovskites. For example, he cites hybrid organic-inorganic perovskites (HOIPs), which have much more complicated recipes, as well as lead-free double-perovskite variants that are more environmentally friendly.

“This study shows why this perovskite framework is special even in the simplest of cases,” said Delaire. “These findings very likely extend to much more complicated recipes, which many scientists throughout the world are currently researching. As they screen enormous computational databases, the dynamics we’ve uncovered could help decide which perovskites to pursue.”

Source link

Continue Reading
1 Comment

1 Comment

  1. Pingback: Combining solar panels and lamb grazing increases land productivity, study finds

Leave a Reply

Solar Energy

Research team achieves significant solar cell efficiency milestone

Published

on

By

Research team achieves significant solar cell efficiency milestone


Research team achieves significant solar cell efficiency milestone

by Simon Mansfield

Sydney, Australia (SPX) May 26, 2024






A research team has created a tandem solar cell using antimony selenide as the bottom cell material and a hybrid perovskite material as the top cell, achieving over 20 percent power conversion efficiency. This advancement highlights antimony selenide’s potential for bottom cell applications.

Photovoltaic technology converts sunlight into electricity, offering a clean energy source. Scientists aim to enhance the efficiency of solar cells, achieving over 20 percent in conventional single-junction cells. Surpassing the Shockley-Queisser limit in these cells would be costly, but tandem solar cells can overcome this limit by stacking materials.



The team focused on antimony selenide for tandem cells, traditionally used in single-junction cells. “Antimony selenide is a suitable bottom cell material for tandem solar cells. However, because of the rarity of reported tandem solar cells using it as a bottom cell, little attention has been paid to its application. We assembled a tandem solar cell with high conversion efficiency using it as the bottom cell to demonstrate the potential of this material,” said Tao Chen, professor of Materials Science and Engineering at the University of Science and Technology of China.



Tandem cells absorb more sunlight than single-junction cells, converting more light into electricity. The team created perovskite/antimony selenide tandem cells with a transparent conducting electrode, optimizing the spectral response and achieving over 17 percent efficiency. By optimizing the antimony selenide bottom cell, they reached 7.58 percent efficiency.



The assembled four-terminal tandem cell achieved 20.58 percent efficiency, higher than independent subcells. The tandem cell is stable and uses nontoxic elements. “This work provides a new tandem device structure and demonstrates that antimony selenide is a promising absorber material for bottom cell applications in tandem solar cells,” said Chen.



The team aims to develop an integrated two-terminal tandem cell and further improve performance. “The high stability of antimony selenide provides great convenience for the preparation of two-terminal tandem solar cell, which means that it may have good results when paired with quite a few different types of top cell materials.”



Research Report:Sb2Se3 as a bottom cell material for efficient perovskite/Sb2Se3 tandem solar cells


Related Links

Tsinghua University

All About Solar Energy at SolarDaily.com





Source link

Continue Reading

Solar Energy

Flower or power? Campaigners fear lithium mine could kill rare plant

Published

on

By

Flower or power? Campaigners fear lithium mine could kill rare plant


Flower or power? Campaigners fear lithium mine could kill rare plant

By Romain FONSEGRIVES

Rhyolite Ridge, United States (AFP) May 23, 2024






Delicate pink buds sway in the desert breeze, pregnant with yellow pompoms whose explosion will carpet the dusty corner of Nevada that is the only place on Earth where they exist.

Under their roots lie vast reserves of lithium, vital for the rechargeable electric car batteries that will reduce planet-heating pollution.

But campaigners fear the extraction of the precious metal could destroy the flower’s tiny habitat.

“This mine is going to cause extinction,” says Patrick Donnelly, an environmentalist who works at the Center for Biological Diversity, a non-governmental organization.

“They somehow claim that they’re not harming the (plant). But can you imagine if someone built an open-pit mine 200 feet from your house? Wouldn’t that affect your life profoundly?”

The plant in question is Tiehm’s buckwheat.

There are only around 20,000 known specimens, growing in a few very specific places on a total surface area equivalent to around five soccer fields.

In 2022, the wildflower was classified as endangered by US federal authorities, with mining cited as a major threat to its survival.

The plant and the lithium reserve on which it grows embody one of the key challenges and contradictions of the global climate struggle: how much damage can we inflict on the natural world as we seek to halt or reverse the problems we have already created?

– ‘Coexist’ –

Bernard Rowe, boss of Australian miner Ioneer, which holds the mineral rights to the area, says the lithium produced at Rhyolite Ridge “will be sufficient to provide batteries for about 370,000 vehicles” a year.

“We’ll do that year-on-year for 26 years,” he said.

Those nearly 10 million vehicles will go a long way towards meeting the goal President Joe Biden has set of cutting down the nation’s fleet of gas-guzzlers as a way to slash US production of planet-warming pollutants.

So-called zero-emission cars make up around 7.5 percent of new vehicle sales in the United States today — more than double the percentage just a few years earlier.

In California, the figure is more than 20 percent.

And while expansion in the sector has slowed, the category remains the fastest-growing, according to Kelley Blue Book.

And it’s not only in the United States: Global demand for lithium will increase five to seven times by 2030, according to the International Energy Agency.

The difficulty for US manufacturers is that much of the world’s lithium supply is dominated by strategic rival China, as well as Australia and Chile.

“The United States has very, very little domestic production,” said Rowe.

“So it’s important to develop a domestic supply chain to allow for that energy transition, and Rhyolite Ridge will be an integral part of that.”

Ioneer’s plans show that over the years the mine is in operation — it is projected to start producing lithium in late 2027 — around a fifth of the plant’s habitat will be directly affected.

But the company, which has spent $2.5 million researching the plant, says mining will not affect its survival; it is already growing well in greenhouses and biologists think it can be replanted.

“We’re very confident that the mine and Tiehm’s buckwheat can coexist,” Rowe said.

– ‘Greenwashing’ –

Donnelly counters that Ioneer is “basically greenwashing extinction.”

“They’re saying. ‘We’re going to save this plant,’ when actually they are going to send it to its doom,” he said.

Under the company’s plans, the strip mine will use hundreds of trucks, which Donnelly says will raise clouds of dust that will affect photosynthesis and harm the insects that pollinate the plants.

Ioneer says it has already planned mitigation methods, like dust curtains, and keeping the roads wet.

Still, Donnelly says, why not just move the mine? But Rowe counters that it’s not as simple as just digging somewhere else.

Ioneer has invested $170 million since 2016 to demonstrate the feasibility of this site, which it believes is one of the best around.

“Many of these other deposits haven’t had that amount of work, so they’re not viable alternatives to a project like this,” he said.

The US Department of Energy has offered Ioneer a $700 million loan for the project, if the Bureau of Land Management signs off on an operating permit.

Donnelly insists the issue is not just the future of one obscure wildflower, but rather just one example of large-scale biodiversity loss that is threatening millions of plants and animals.

“If we solve the climate crisis, but we drive everything extinct while we do it, we’re still going to lose our world,” he said.

Related Links

Powering The World in the 21st Century at Energy-Daily.com





Source link

Continue Reading

Solar Energy

Tesla breaks ground on huge Shanghai battery plant

Published

on

By

Tesla breaks ground on huge Shanghai battery plant


Tesla breaks ground on huge Shanghai battery plant

by AFP Staff Writers

Shanghai (AFP) May 23, 2024






Tesla broke ground on a massive battery factory in Shanghai on Thursday, Chinese state media reported, making it the US electric car giant’s second plant in the financial hub.

The project was announced last April after boss Elon Musk presented a vague but ambitious plan to investors to turbocharge growth.

However, the company last month reported a 55 percent drop in quarterly earnings, reflecting a decline in EV sales in an intensively competitive market.

The new Shanghai factory should make 10,000 units per year of Tesla’s Megapack batteries, state news agency Xinhua said.

Tesla says Megapacks are intended to store energy and stabilise supply for power grids, with each unit able to store more than three megawatt-hours of power.

The factory is expected to start mass production in 2025, state media said in May.

“I believe the new plant is a milestone for both Shanghai and Tesla,” the company’s vice president Tao Lin told Xinhua.

“In a more open environment, we can… supply the global market with large-scale energy-storage batteries manufactured in China.”

Musk has extensive business interests in China and is a fairly frequent visitor.

In April, he met Chinese Premier Li Qiang, and received a key security clearance for Tesla’s locally produced EVs.

Musk’s interests in China have long raised eyebrows in Washington — President Joe Biden has said in the past that his links to foreign countries were “worthy” of scrutiny.

The battery plant will be Tesla’s second in the Chinese city after its enormous Shanghai Gigafactory, which broke ground in 2019.

Related Links

Powering The World in the 21st Century at Energy-Daily.com





Source link

Continue Reading

Trending

Copyright © 2017 Zox News Theme. Theme by MVP Themes, powered by WordPress.