Stability of perovskite solar cells boosted with innovative protective layer

by Clarence Oxford

Los Angeles CA (SPX) Nov 22, 2024

Scientists at Northwestern University have unveiled a new protective coating that dramatically improves the longevity of perovskite solar cells, a key step toward making these cells viable for real-world applications.

Perovskite solar cells offer greater efficiency and lower costs compared to traditional silicon-based cells. However, their lack of durability has historically hindered widespread adoption. Conventional coatings using ammonium-based compounds, while effective at enhancing efficiency, degrade quickly under environmental stresses such as heat and moisture.

To address this limitation, the research team introduced an amidinium-based protective layer, which outperformed ammonium coatings by a significant margin. Laboratory tests revealed that this innovative layer is 10 times more resistant to decomposition. Moreover, it tripled the cells’ T90 lifetime – the duration before a cell’s efficiency drops to 90% of its initial level under extreme conditions.

“The field has been working on the stability of perovskite solar cells for a long time,” said Bin Chen, a co-leader of the study. “So far, most reports focus on improving the stability of the perovskite material itself, overlooking the protective layers. By improving the protective layer, we were able to enhance the solar cells’ overall performance.”

Published in ‘Science’, the study marks a critical advancement in perovskite solar cell technology.

“This work addresses one of the critical barriers to widespread adoption of perovskite solar cells – stability under real-world conditions,” explained Mercouri Kanatzidis, another study co-leader. “By chemically reinforcing the protective layers, we’ve significantly advanced the durability of these cells without compromising their exceptional efficiency, bringing us closer to a practical, low-cost alternative to silicon-based photovoltaics.”

Bridging the Durability Gap

Although silicon remains the most widely used material for solar cells due to its reliability and durability, it is costly to produce and nearing its maximum efficiency potential. Researchers have turned to perovskites as a more affordable, higher-efficiency alternative. However, perovskite’s limited lifespan under sunlight, temperature fluctuations, and moisture has remained a major challenge.

The Northwestern team tackled this issue by using amidinium ligands, stable molecules capable of interacting with perovskites to enhance protection and prevent defects. Compared to ammonium-based molecules, amidinium compounds are more structurally resilient under harsh conditions.

“State-of-the-art perovskite solar cells typically have ammonium ligands as a passivation layer,” said Yi Yang, the study’s first author. “But ammonium tends to break down under thermal stress. We did some chemistry to convert the unstable ammonium into a more stable amidinium.”

This transformation, achieved through a chemical process called amidination, replaced the ammonium group with amidinium, preventing degradation and improving thermal stability.

Record-Setting Performance

With this innovation, the perovskite solar cells achieved an efficiency of 26.3%, converting 26.3% of sunlight into usable electricity. Additionally, the amidinium-coated cells maintained 90% of their initial efficiency after 1,100 hours of rigorous testing under heat and light, demonstrating their vastly improved durability.

These results build on previous advancements from Northwestern’s research team. Over the past two years, the Sargent lab has achieved record-breaking energy efficiency, introduced inverted perovskite structures, and incorporated liquid crystals to enhance cell performance.

“Perovskite-based solar cells have the potential to contribute to the decarbonization of the electricity supply once we finalize their design, achieve the union of performance and durability, and scale the devices,” said Ted Sargent, co-leader of the study. “The primary barrier to the commercialization of perovskite solar cells is their long-term stability. But due to its multi-decade head start, silicon still has an advantage in some areas, including stability. We are working to close that gap.”

The study supports the Trienens Institute’s Generate pillar, which focuses on advancing solar energy production through innovative technologies. By improving perovskite solar cells, Northwestern aims to develop the next generation of efficient, cost-effective solar solutions.

Research Report:Amidination of ligands for chemical and field-effect passivation stabilizes perovskite solar cells

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Northwestern University

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More energy and oil possible through combining photovoltaic plants with hedgerow olive groves

by Hugo Ritmico

Madrid, Spain (SPX) Nov 20, 2024

The integration of photovoltaic plants on agricultural land has long sparked debate over balancing energy production with crop cultivation. Now, the innovative approach of combining both has gained momentum with promising results. This “agrivoltaic” system, which involves placing solar panels within agricultural setups, has been examined by a University of Cordoba research team to see if solar energy and agricultural production could mutually enhance each other.

The research group, including Marta Varo Martinez, Luis Manuel Fernandez de Ahumada, and Rafael Lopez Luque from the Physics for Renewable Energies and Resources group, along with Alvaro Lopez Bernal and Francisco Villalobos from the Soil-Water-Plant Relations group, developed a model that simulates an agrivoltaic system in hedgerow olive plantations. This simulation model combined predictions for oil yield from olive hedgerows and energy generation from solar collectors to assess combined productivity. The study concluded that using both in tandem increased overall productivity, marking a potential shift in land-use strategy that could cater to the needs for both clean energy and food.

The key findings show that mutual benefits arise when solar panels provide shade, acting as windbreaks that don’t compete for water, enhancing agricultural production. Meanwhile, the cooling effect from plant evapotranspiration can improve the efficiency of solar collectors by reducing their temperature, boosting energy output.

This model allows researchers to experiment with various collector configurations, adjusting heights, widths, and spacing, to pinpoint the most effective designs. Despite generally positive outcomes, the team noted that overly dense arrangements might limit space for machinery or complicate maintenance of the olive grove. The approach underscores the importance of balancing land-use density and operational accessibility.

Research Report:Simulation model for electrical and agricultural productivity of an olive hedgerow Agrivoltaic system

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University of Cordoba

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New initiative empowers Native American women with solar training

by Clarence Oxford

Los Angeles CA (SPX) Nov 20, 2024

Native American women across the country are gaining access to hands-on training in photovoltaic panel installation aimed at empowering them to establish solar systems in their communities and homes on tribal land.

Sandra Begay, an engineer at Sandia National Laboratories and a Navajo Nation member, is one of four mentors guiding this effort.

This training initiative is part of a Cooperative Research and Development Agreement between Sandia and Red Cloud Renewable, a nonprofit organization in Pine Ridge, South Dakota, that focuses on advancing energy independence for tribal members and communities.

Known as the Bridging Renewable Industry Divides in Gender Equality, or BRIDGE, Program, the initiative provides a five-week immersive training experience that emphasizes practical skills in photovoltaic installation.

In August, Begay joined the first group of participants in South Dakota.

“Five weeks is a long time to be away from home,” Begay said. “I provided encouragement and reminded the women that they made the right choice to participate in this program. We also used the time to reflect on what they learned.”

Participants are taught the components of photovoltaic systems and how to install them safely and effectively.

Begay also provided insight into the energy challenges faced by tribal communities.

“There are more than 20,000 homes on the Navajo Nation and some rural homes on the Hopi reservation that don’t have electricity. These are off-grid homes,” Begay said, noting that many of these homes depend on diesel generators. “We’re looking at a clean energy future. We want to move away from those types of fuels and look at clean energy sources such as solar.”

She highlighted that large-scale solar projects are being developed by the Navajo Nation and the Mountain Ute Tribe in Colorado.

“This program will provide participants with new employment opportunities and a better understanding of where we’re headed with clean energy,” Begay said.

Red Cloud Renewable also supports the women with resume building, interview training, networking, and job placement services.

With over 30 years of experience championing renewable energy in Native American communities, Begay is committed to maintaining relationships with participants.

“I am making a long-term commitment to the women in the BRIDGE Program,” Begay said. “I will share any job openings I see with them and support them in their job searches.”

Teamwork for success

Begay emphasized the critical role teamwork plays in photovoltaic installations.

“Photovoltaic installation happens with a team of people. How do you work through that group dynamic? How do you work with each other as a team? Those questions are underemphasized in the work we do. They’re going to rely on each other when installing photovoltaic systems,” she said.

Alicia Hayden, Red Cloud Renewable’s communications manager, noted the strong bond formed among the participants.

“What stood out to me was the incredible camaraderie among the women,” Hayden said. “They were genuinely supportive of each other and grateful to be participating in this program alongside women who share similar backgrounds.”

Funded by the Department of Energy’s Solar Energy Technology Office, the project is set to continue over the next few years and aims to train two additional groups, eventually involving around 45 women.

“These women will be equipped to take on installer jobs within their own reservations, bringing valuable skills and opportunities for sustainable development to their people,” Hayden said.

Despite being highly underrepresented in the solar industry – comprising just 0.05% of the sector, according to Red Cloud Renewable – Native American women stand to gain from this initiative.

Begay expressed optimism about the impact of the BRIDGE Program.

“It’s very gratifying both professionally and personally to see where we can help women who are underrepresented in the workforce, let alone in a unique technology like photovoltaic installation,” Begay said. “We’re seeding ideas for the women that they would never have thought of doing. I think that’s what’s unique.”

Related Links

Sandia National Laboratories

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