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Inverted perovskite solar cell breaks 25% efficiency record

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Inverted perovskite solar cell breaks 25% efficiency record


Inverted perovskite solar cell breaks 25% efficiency record

by Staff Writers

Evanston IL (SPX) Nov 21, 2023






Northwestern University researchers have raised the standards again for perovskite solar cells with a new development that helped the emerging technology hit new records for efficiency. The findings, published Nov. 17 in the journal Science, describe a dual-molecule solution to overcoming losses in efficiency as sunlight is converted to energy.

By incorporating first, a molecule to address something called surface recombination, in which electrons are lost when they are trapped by defects – missing atoms on the surface, and a second molecule to disrupt recombination at the interface between layers, the team achieved a National Renewable Energy Lab (NREL) certified efficiency of 25.1% where earlier approaches reached efficiencies of just 24.09%.



“Perovskite solar technology is moving fast, and the emphasis of research and development is shifting from the bulk absorber to the interfaces,” said Northwestern professor Ted Sargent. “This is the critical point to further improve efficiency and stability and bring us closer to this promising route to ever-more-efficient solar harvesting.”



Sargent is the co-executive director of the Paula M. Trienens Institute for Sustainability and Energy (formerly ISEN) and a multidisciplinary researcher in materials chemistry and energy systems, with appointments in the department of chemistry in the Weinberg College of Arts and Sciences and the department of electrical and computer engineering in the McCormick School of Engineering.



Conventional solar cells are made of high-purity silicon wafers that are energy-intensive to produce and can only absorb a fixed range of the solar spectrum.



Perovskite materials whose size and composition can be adjusted to “tune” the wavelengths of light they absorb, making them a favorable and potentially lower-cost, high-efficiency emerging tandem technology.



Historically perovskite solar cells have been plagued by challenges to improve efficiency because of their relative instability. Over the past few years, advances from Sargent’s lab and others have brought the efficiency of perovskite solar cells to within the same range as what is achievable with silicon.



In the present research, rather than trying to help the cell absorb more sunlight, the team focused on the issue of maintaining and retaining generated electrons to increase efficiency. When the perovskite layer contacts the electron transport layer of the cell, electrons move from one to the other. But the electron can move back outward and fill, or “recombine” with holes that exist on the perovskite layer.



“Recombination at the interface is complex,” said first author Cheng Liu, a postdoctoral student in the Sargent lab, which is co-supervised by the Charles E. and Emma H. Morrison Professor of Chemistry Mercouri Kanatzidis. “It’s very difficult to use one type of molecule to address complex recombination and retain electrons, so we considered what combination of molecules we could use to more comprehensively solve the problem.”



Past research from Sargent’s team has found evidence that one molecule, PDAI2, does a good job at solving interface recombination. Next they needed to find a molecule that would work to repair surface defects and prevent electrons from recombining with them.



By finding the mechanism that would allow PDAI2 to work with a secondary molecule, the team narrowed in on sulfur, which could replace carbon groups – typically poor at preventing electrons from moving – to cover missing atoms and suppress recombination.



A recent paper by the same group published in Nature developed a coating for the substrate beneath the perovskite layer to help the cell work at a higher temperature for a longer period. This solution, according to Liu, can work in tandem with the findings within the Science paper.



While the team hopes their findings will encourage the larger scientific community to continue moving the work forward, they too will be working on follow-ups.



“We have to use a more flexible strategy to solve the complex interface problem,” Cheng said. “We can’t only use one kind of molecule, as people previously did. We use two molecules to solve two kinds of recombination, but we are sure there’s more kinds of defect-related recombination at the interface. We need to try to use more molecules to come together and make sure all molecules work together without destroying each other’s functions.”



Research Report:Bimolecularly-passivated interface enables efficient and stable inverted perovskite solar cells


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Argentina starts removing solar panels from Chilean border

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Argentina starts removing solar panels from Chilean border


Argentina starts removing solar panels from Chilean border

by AFP Staff Writers

Santiago (AFP) June 17, 2024






Argentina on Monday began removing solar panels that were installed by accident on the wrong side of its shared border with Chile, after a complaint from Chilean President Gabriel Boric.

In late April, the Argentine Navy inaugurated a maritime surveillance post on the border with Chile, in the Patagonia region of South America.

But the solar panels, which provide energy to that military unit, were set up on the Chilean side of the frontier.

In a statement, the Argentine Navy acknowledged the mistake and said it had “transferred personnel and means to begin the removal of a solar panel installed in the territory of the sister republic of Chile, north of the Island of Tierra del Fuego.”

Earlier in the day, Boric demanded that the panels be removed or Chile itself would do it.

“Borders are not something that can be ambiguous. It is a basic principle of respect between countries and therefore they must remove those solar panels as soon as possible or we are going to do it,” Boric told reporters during a visit to Paris.

Chile and Argentina share a border of about 5,000 kilometers (more than 3,000 miles).

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Chinese Premier Li targets clean energy in Australia visit

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Chinese Premier Li targets clean energy in Australia visit


Chinese Premier Li targets clean energy in Australia visit

by AFP Staff Writers

Sydney (AFP) June 18, 2024






Premier Li Qiang toured a Chinese-controlled lithium refiner in Perth on Tuesday, a sign of his country’s vast appetite for Australian “critical minerals” required for clean energy technologies.

Li ended his four-day visit to Australia with a tour of the low-carbon energy industry in resource-rich Western Australia.

His first stop was Tianqi Lithium Energy Australia, a 51-percent Chinese-owned venture comprising a mine for hard rock lithium ore, and a lithium refinery.

Along with at least a dozen other officials, China’s second most powerful man donned a white helmet during a rainy visit to the facility south of Perth.

The Chinese premier will also view a private research facility for clean energy-produced “green hydrogen” — touted as a fuel of the future to power heavy-duty items such as trucks and blast furnaces.

Australia extracts 52 percent of the world’s lithium, the vast majority of it exported as an ore to China for eventual refining and use in batteries, notably in China’s world-dominant electric vehicle industry.

But despite being a huge Australian customer, China’s involvement in the country’s critical mineral industry is sensitive because of its dominance of global supply chains.

Australia has only recently begun refining lithium rather than exporting the ore.

And the government has announced a strategic plan to develop new supply chains with friendly countries for critical minerals such as lithium, nickel and so-called rare earths.

Earlier this year, the government ordered five China-linked shareholders to sell off a combined 10 percent stake in Northern Minerals, a producer of the rare earth dysprosium.

Such foreign ownership was against Australia’s “national interests”, Treasurer Jim Chalmers said.

About 99 percent of the world’s dysprosium — used in high-performance magnets — is currently produced in China.

China has invested in critical minerals in Latin America, Africa and Australia over the past 10-20 years, said Marina Zhang, associate professor at the University of Technology Sydney’s Australia-China Relations Institute.

Developing supply chains independent of China is “fine and dandy” but unlikely to be achieved even in the short to medium term, she said.

“We are facing a very time-pressing issue that is fighting against climate change — so that issue should be at the centre of the discourse,” Zhang said.

“But unfortunately the Western allies are taking the approach that China’s dominance across the supply chains of critical minerals is imposing national security threats,” she said.

China’s narrative, however, was that it was investing and making a contribution to sustainability and environmental protection, the analyst said.

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Rice Lab Reports Significant Advances in Perovskite Solar Cell Stability

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Rice Lab Reports Significant Advances in Perovskite Solar Cell Stability


Rice Lab Reports Significant Advances in Perovskite Solar Cell Stability

by Clarence Oxford

Los Angeles CA (SPX) Jun 18, 2024






Solar power is growing rapidly as an energy technology, recognized for its cost-effectiveness and its role in reducing greenhouse gas emissions.

A Rice University study published in Science details a method for synthesizing formamidinium lead iodide (FAPbI3) into stable, high-quality photovoltaic films. The efficiency of these FAPbI3 solar cells declined by less than 3% over more than 1,000 hours of operation at 85 degrees Celsius (185 Fahrenheit).



“Right now, we think that this is state of the art in terms of stability,” said Rice engineer Aditya Mohite. “Perovskite solar cells have the potential to revolutionize energy production, but achieving long-duration stability has been a significant challenge.”



This breakthrough represents a major step towards making perovskite photovoltaics commercially viable. The researchers added specially designed two-dimensional (2D) perovskites to the FAPbI3 precursor solution, which served as a template to enhance the stability of the crystal lattice structure.



“Perovskite crystals get broken in two ways: chemically – destroying the molecules that make up the crystal – and structurally – reordering the molecules to form a different crystal,” explained Isaac Metcalf, a Rice graduate student and a lead author on the study. “Of the various crystals that we use in solar cells, the most chemically stable are also the least structurally stable and vice versa. FAPbI3 is on the structurally unstable end of that spectrum.”



The researchers found that while 2D perovskites are more stable, they are less effective at harvesting light. By using 2D perovskites as templates, they improved the stability and efficiency of FAPbI3 films. The addition of well-matched 2D crystals facilitated the formation of high-quality FAPbI3 films, showing less internal disorder and better illumination response.



The study showed that solar cells with 2D templates retained their efficiency and durability significantly better than those without. Encapsulation layers further enhanced the stability of these solar cells, extending their operational life to timescales relevant for commercial applications.



“Perovskites are soluble in solution, so you can take an ink of a perovskite precursor and spread it across a piece of glass, then heat it up and you have the absorber layer for a solar cell,” Metcalf said. “Since you don’t need very high temperatures – perovskite films can be processed at temperatures below 150 Celsius (302 Fahrenheit) – in theory that also means perovskite solar panels can be made on plastic or even flexible substrates, which could further reduce costs.”



Silicon, the most commonly used semiconductor in photovoltaic cells, requires more resource-intensive manufacturing processes than perovskites, which have seen efficiency improvements from 3.9% in 2009 to over 26% currently.



“It should be much cheaper and less energy-intensive to make high-quality perovskite solar panels compared to high-quality silicon panels, because the processing is so much easier,” Metcalf said.



“We need to urgently transition our global energy system to an emissions-free alternative,” he added, referring to UN estimates that highlight the importance of solar energy in replacing fossil fuels.



Mohite emphasized that advancements in solar energy technologies are crucial for meeting the 2030 greenhouse gas emissions target and preventing a 1.5 degrees Celsius rise in global temperatures, essential for achieving net zero carbon emissions by 2050.



“If solar electricity doesn’t happen, none of the other processes that rely on green electrons from the grid, such as thermochemical or electrochemical processes for chemical manufacturing, will happen,” Mohite said. “Photovoltaics are absolutely critical.”



Mohite holds the title of William M. Rice Trustee Professor at Rice, is a professor of chemical and biomolecular engineering, and directs the Rice Engineering Initiative for Energy Transition and Sustainability. The study’s lead authors also include Siraj Sidhik, a Rice doctoral alumnus.



“I would like to give a lot of credit to Siraj, who started this project based on a theoretical idea by Professor Jacky Even at the University of Rennes,” Mohite said. “I would also like to thank our collaborators at the national labs and at several universities in the U.S. and abroad whose help was instrumental to this work.”



Research Report:Two-dimensional perovskite templates for durable, efficient formamidinium perovskite solar cells


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