Solar Energy

Scientists develop perovskite solar modules with greater size, power and stability

Published

4 years ago

February 8, 2021

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Scientists develop perovskite solar modules with greater size, power and stability

Researchers from the Okinawa Institute of Science and Technology Graduate University (OIST) have created perovskite solar modules with improved stability and efficiency by using a new fabrication technique that reduced defects. Their findings were published on the 25th January in Advanced Energy Materials.

Perovskites are one of the most promising materials for the next-generation of solar technology, soaring from efficiencies of 3.8% to 25.5% in slightly over a decade. Perovskite solar cells are cheap to produce and have the potential to be flexible, increasing their versatility. But two obstacles still block the way to commercialization: their lack of long-term stability and difficulties with upscaling.

“Perovskite material is fragile and prone to decomposition, which means the solar cells struggle to maintain high efficiency over a long time,” said first author Dr. Guoqing Tong, a postdoctoral scholar in the OIST Energy Materials and Surface Sciences Unit, led by Professor Yabing Qi. “And although small-sized perovskite solar cells have a high efficiency and perform almost as well as their silicon counterparts, once scaled up to larger solar modules, the efficiency drops.”

In a functional solar device, the perovskite layer lies in the center, sandwiched between two transport layers and two electrodes. As the active perovskite layer absorbs sunlight, it generates charge carriers which then flow to the electrodes via the transport layers and produce a current.

However, pinholes in the perovskite layer and defects at the boundaries between individual perovskite grains can disrupt the flow of charge carriers from the perovskite layer to the transport layers, reducing efficiency. Humidity and oxygen can also start to degrade the perovskite layer at these defect sites, shortening the lifespan of the device.

“Scaling up is challenging because as the modules increase in size, it’s harder to produce a uniform layer of perovskite, and these defects become more pronounced,” explained Dr. Tong. “We wanted to find a way of fabricating large modules that addressed these problems.”

Currently, most solar cells produced have a thin perovskite layer – only 500 nanometers in thickness. In theory, a thin perovskite layer improves efficiency, as the charge carriers have less distance to travel to reach the transport layers above and below. But when fabricating larger modules, the researchers found that a thin film often developed more defects and pinholes.

The researchers therefore opted to make 5 x 5 cm2 and 10 x 10 cm2 solar modules that contained perovskite films with double the thickness.

However, making thicker perovskite films came with its own set of challenges. Perovskites are a class of materials that are usually formed by reacting many compounds together as a solution and then allowing them to crystallize.

However, the scientists struggled to dissolve a high enough concentration of lead iodine – one of the precursor materials used to form perovskite – that was needed for the thicker films. They also found that the crystallization step was fast and uncontrollable, so the thick films contained many small grains, with more grain boundaries.

The researchers therefore added ammonium chloride to increase the solubility of lead iodine. This also allowed lead iodine to be more evenly dissolved in the organic solvent, resulting in a more uniform perovskite film with much larger grains and fewer defects. Ammonia was later removed from the perovskite solution, lowering the level of impurities within the perovskite film.

Overall, the solar modules sized 5 x 5 cm2 showed an efficiency of 14.55%, up from 13.06% in modules made without ammonium chloride, and were able to work for 1600 hours – over two months – at more than 80% of this efficiency.

The larger 10 x 10 cm2 modules had an efficiency of 10.25% and remained at high levels of efficiency for over 1100 hours, or almost 46 days.

“This is the first time that a lifespan measurement has been reported for perovskite solar modules of this size, which is really exciting,” said Dr. Tong.

This work was supported by the OIST Technology Development and Innovation Center’s Proof-of-Concept Program. These results are a promising step forward in the quest to produce commercial-sized solar modules with efficiency and stability to match their silicon counterparts.

In the next stage of their research, the team plans to optimize their technique further by fabricating the perovskite solar modules using vapor-based methods, rather than by using solution, and are now trying to scale up to 15 x 15 cm2 modules.

“Going from lab-sized solar cells to 5 x 5 cm2 solar modules was hard. Jumping up to solar modules that were 10 x 10 cm2 was even harder. And going to 15 x 15 cm2 solar modules will be harder still,” said Dr. Tong. “But the team is looking forward to the challenge.”

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Solar Energy

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

Published

2 days ago

November 20, 2024

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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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Solar Energy

New initiative empowers Native American women with solar training

Published

2 days ago

November 20, 2024

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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.”

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Solar Energy

Perovskite advancements improve solar cell efficiency and longevity

Published

2 days ago

November 20, 2024

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Perovskite advancements improve solar cell efficiency and longevity

by Sophie Jenkins

London, UK (SPX) Nov 20, 2024

A global team led by the University of Surrey, in collaboration with Imperial College London, has pioneered a method to enhance the efficiency and durability of solar cells constructed from perovskite by addressing an unseen degradation pathway.

The University of Surrey’s Advanced Technology Institute (ATI) detailed their findings in ‘Energy and Environmental Science’, showing that by employing specific design strategies, they successfully created lead-tin perovskite solar cells achieving over 23% power conversion efficiency (PCE) – a significant result for this material type. Notably, these improvements also boosted the operational lifespan of these cells by 66%. PCE measures the proportion of sunlight converted to usable energy by a solar cell.

While traditional silicon solar panels are already widely used, advancements are steering towards perovskite/silicon hybrid panels, and fully perovskite-based panels promise even higher efficiencies. However, improving the stability and efficiency of lead-tin perovskite cells remains a significant hurdle. This research by the University of Surrey sheds light on mechanisms contributing to these limitations and offers a pathway to overcoming them, aiding in the broader advancement of solar technology.

Hashini Perera, Ph.D. student and lead author at ATI, stated: “The understanding we have developed from this work has allowed us to identify a strategy that improves the efficiency and extends the operational lifetime of these devices when exposed to ambient conditions. This advancement is a major step towards high efficiency, long-lasting solar panels which will give more people access to affordable clean energy while reducing the reliance on fossil fuels and global carbon emissions.”

The team focused on minimizing losses caused by the hole transport layer, crucial for solar cell functionality. By introducing an iodine-reducing agent, they mitigated the degradation effects, enhancing both the cell’s efficiency and its lifespan. This innovation paves the way for more sustainable and economically feasible solar technology.

Dr. Imalka Jayawardena from the University of Surrey’s ATI, co-author of the study, said: “By significantly enhancing the efficiency of our perovskite-based solar cells, we are moving closer to producing cheaper and more sustainable solar panels. We are already working on refining these materials, processes and the device architecture to tackle the remaining challenges.”

Professor Ravi Silva, Director of the ATI, added: “This research brings us closer to panels that not only generate more power over their lifetime but are also longer lasting. Greater efficiency and fewer replacements mean more green energy with less waste. The University of Surrey are in the process of building a 12.5MW solar farm, where we can test some of these modules. We’re confident that our innovative perovskite research will accelerate the widespread commercial adoption of perovskite-based solar panels.”

This progress aligns with the UN Sustainable Development Goals, specifically Goals 7 (affordable and clean energy), 9 (industry, innovation, and infrastructure), and 13 (climate action).

Research Report:23.2% efficient low band gap perovskite solar cells with cyanogen management