Solar Energy

Squeezing a rock-star material could make it stable enough for solar cells

Published

4 years ago

February 8, 2021

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Squeezing a rock-star material could make it stable enough for solar cells

Among the materials known as perovskites, one of the most exciting is a material that can convert sunlight to electricity as efficiently as today’s commercial silicon solar cells and has the potential for being much cheaper and easier to manufacture.

There’s just one problem: Of the four possible atomic configurations, or phases, this material can take, three are efficient but unstable at room temperature and in ordinary environments, and they quickly revert to the fourth phase, which is completely useless for solar applications.

Now scientists at Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory have found a novel solution: Simply place the useless version of the material in a diamond anvil cell and squeeze it at high temperature. This treatment nudges its atomic structure into an efficient configuration and keeps it that way, even at room temperature and in relatively moist air.

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

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

A search for stability

Perovskites get their name from a natural mineral with the same atomic structure. In this case the scientists studied a lead halide perovskite that’s a combination of iodine, lead and cesium.

One phase of this material, known as the yellow phase, does not have a true perovskite structure and can’t be used in solar cells. However, scientists discovered a while back that if you process it in certain ways, it changes to a black perovskite phase that’s extremely efficient at converting sunlight to electricity. “This has made it highly sought after and the focus of a lot of research,” said Stanford Professor and study co-author Wendy Mao.

Unfortunately, these black phases are also structurally unstable and tend to quickly slump back into the useless configuration. Plus, they only operate with high efficiency at high temperatures, Mao said, and researchers will have to overcome both of those problems before they can be used in practical devices.

There had been previous attempts to stabilize the black phases with chemistry, strain or temperature, but only in a moisture-free environment that doesn’t reflect the real-world conditions that solar cells operate in. This study combined both pressure and temperature in a more realistic working environment.

Pressure and heat do the trick

Working with colleagues in the Stanford research groups of Mao and Professor Hemamala Karunadasa, Lin and postdoctoral researcher Feng Ke designed a setup where yellow phase crystals were squeezed between the tips of diamonds in what’s known as a diamond anvil cell. With the pressure still on, the crystals were heated to 450 degrees Celsius and then cooled down.

Under the right combination of pressure and temperature, the crystals turned from yellow to black and stayed in the black phase after the pressure was released, the scientists said. They were resistant to deterioration from moist air and remained stable and efficient at room temperature for 10 to 30 days or more.

Examination with X-rays and other techniques confirmed the shift in the material’s crystal structure, and calculations by SIMES theorists Chunjing Jia and Thomas Devereaux provided insight into how the pressure changed the structure and preserved the black phase.

The pressure needed to turn the crystals black and keep them that way was roughly 1,000 to 6,000 times atmospheric pressure, Lin said – about a tenth of the pressures routinely used in the synthetic diamond industry. So one of the goals for further research will be to transfer what the researchers have learned from their diamond anvil cell experiments to industry and scale up the process to bring it within the realm of manufacturing.

The researchers described their results in Nature Communications.

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Solar Energy

A single molecule elevates solar module output and stability

Published

2 days ago

April 24, 2025

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A single molecule elevates solar module output and stability

by Sophie Jenkins

London, UK (SPX) Apr 24, 2025

A new molecule developed through international collaboration has been shown to significantly improve both the performance and durability of perovskite solar cells, according to a recent study published in *Science*. The discovery centers on a synthetic ionic salt named CPMAC, which originates from buckminsterfullerene (C60) and has been shown to outperform traditional C60 in solar applications.

Researchers from the King Abdullah University of Science and Technology (KAUST) played a key role in the development of CPMAC. While C60 has long been used in perovskite solar cells due to its favorable electronic properties, it suffers from stability issues caused by weak van der Waals interactions at the interface with the perovskite layer. CPMAC was engineered to address these shortcomings.

“For over a decade, C60 has been an integral component in the development of perovskite solar cells. However, weak interactions at the perovskite/C60 interface lead to mechanical degradation that compromises long-term solar cell stability. To address this limitation, we designed a C60-derived ionic salt, CPMAC, to significantly enhance the stability of the perovskite solar cells,” explained Professor Osman Bakr, Executive Faculty of the KAUST Center of Excellence for Renewable Energy and Sustainable Technologies (CREST).

Unlike C60, CPMAC forms ionic bonds with the perovskite material, strengthening the electron transfer layer and thereby enhancing both structural stability and energy output. Cells incorporating CPMAC demonstrated a 0.6% improvement in power conversion efficiency (PCE) compared to those using C60.

Though the gain in efficiency appears modest, the impact scales up dramatically in real-world energy production. “When we deal with the scale of a typical power station, the additional electricity generated even from a fraction of a percentage point is quite significant,” said Hongwei Zhu, a research scientist at KAUST.

Beyond efficiency gains, CPMAC also enhanced device longevity. Under accelerated aging tests involving high heat and humidity over 2,000 hours, solar cells containing CPMAC retained a significantly higher portion of their efficiency. Specifically, their degradation was one third that observed in cells using conventional C60.

Further performance evaluation involved assembling the cells into four-cell modules, offering a closer approximation to commercial-scale solar panels. These tests reinforced the molecule’s advantage in both durability and output.

The key to CPMAC’s success lies in its capacity to reduce defects within the electron transfer layer, thanks to the formation of robust ionic bonds. This approach circumvents the limitations posed by van der Waals forces typical of unmodified C60 structures.

Research Report:C60-based ionic salt electron shuttle for high-performance inverted perovskite solar modules

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Solar Energy

Indonesia says China’s Huayou to replace LGES in EV battery project

Published

2 days ago

April 24, 2025

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Indonesia says China’s Huayou to replace LGES in EV battery project

by AFP Staff Writers

Jakarta (AFP) April 23, 2025

China’s Zhejiang Huayou Cobalt is replacing South Korea’s LG Energy Solution as a strategic investor in a multibillion-dollar project to build an electric vehicle battery joint venture in Indonesia, officials said on Wednesday.

The South Korean company, which was part of a consortium that signed a 142 trillion rupiah ($8.4 billion) “Grand Project” in 2020, announced its withdrawal from the project this week, citing factors including market conditions and the investment environment.

Energy and Mineral Resources Minister Bahlil Lahadalia said LG Energy Solution’s decision would not significantly affect the project, which aims to establish a local electric vehicle battery value chain in Indonesia.

“Changes only occur at the investor level, where LG no longer continue its involvement… and has been replaced by a strategic partner from China, namely Huayou,” Bahlil said in a statement.

“Nothing has changed from the initial goal, namely making Indonesia as the center of the world’s electric vehicle industry.”

Indonesia, home to the world’s largest nickel reserve, has been seeking to position itself as a key player in the global electric vehicle supply chain by leveraging its vast reserve of the critical mineral to attract investments.

The government decided not to move forward with the South Korean company in the project due to the long negotiation process with the firm to realise its investment, Investment Minister Rosan Roeslani said.

Rosan cited Huayou’s familiarity with Indonesia as one of the reasons why the government chose the company to succeed LG Energy Solution.

“Huayou had invested in Indonesia,” Rosan said.

“They have sources to develop the industry going forward.”

LG Energy Solution said in a statement on Tuesday that it will continue to explore “various avenues of collaboration” with the Indonesian government, including in its battery joint venture.

HLI Green Power, a joint venture between LG Energy Solution and Hyundai Motor Group, operates Indonesia’s first electric vehicle battery plant, which was launched in 2024 with a production capacity of up to 10 Gigawatt hours (GWh) of cells annually.

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Solar Energy

Politecnico di Milano explores global potential of agrivoltaics for land use harmony

Published

3 days ago

April 23, 2025

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Politecnico di Milano explores global potential of agrivoltaics for land use harmony

by Erica Marchand

Paris, France (SPX) Apr 23, 2025

A research team from the Politecnico di Milano has presented new insights into how agrivoltaic systems could resolve growing tensions over land use between agricultural production and solar energy development. Led by Maddalena Curioni, Nikolas Galli, Giampaolo Manzolini, and Maria Cristina Rulli, the study demonstrates that integrating photovoltaic panels with crop cultivation can significantly mitigate land-use conflict while maintaining food output.

Published in the journal Earth’s Future, the study highlights that between 13% and 16% of existing ground-mounted solar installations have displaced former farmland, underscoring the competition for arable land. In contrast, the researchers propose that deploying agrivoltaic systems on between 22% and 35% of non-irrigated agricultural land could enable dual use without substantially affecting crop yields.

Using a spatial agro-hydrological model, the researchers simulated how 22 crop types respond to varying degrees of solar shading from photovoltaic panels. Their simulations covered a broad range of climates and geographies, generating a global suitability map for agrivoltaic deployment. The results underscore the feasibility of this approach in many regions, especially those with compatible crops and moderate solar intensity.

“Agrivoltaics cannot be applied everywhere, but according to our results, it would be possible to combine cultivation and energy production in many areas of the world without significant reductions in yield,” said Nikolas Galli, researcher at the Glob3Science Lab and co-author of the study.

Giampaolo Manzolini, professor in the Department of Energy, noted additional benefits: “Using the land for both cultivation and photovoltaic systems increases overall output per occupied surface area while reducing production costs. In addition, installing crops underneath the photovoltaic panels reduces the panel operating temperature and increases their efficiency.”

“This technology could help reduce land competition while improving the sustainability of agricultural and energy systems,” added Maria Cristina Rulli, who coordinated the research.

The team emphasizes that their findings could inform strategic policy decisions and investment strategies aimed at maximizing land productivity while supporting both food security and renewable energy goals.

Research Report:Global Land-Water Competition and Synergy Between Solar Energy and Agriculture