Solar Energy

Use of perovskite will be a key feature of the next generation of electronic appliances

Published

4 years ago

March 15, 2021

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Use of perovskite will be a key feature of the next generation of electronic appliances

Quantum dots are manmade nanoparticles of semiconducting material comprising only a few thousand atoms. Because of the small number of atoms, a quantum dot’s properties lie between those of single atoms or molecules and bulk material with a huge number of atoms. By changing the nanoparticles’ size and shape, it is possible to fine-tune their electronic and optical properties – how electrons bond and move through the material, and how light is absorbed and emitted by it.

Thanks to increasingly refined control of the nanoparticles’ size and shape, the number of commercial applications has grown. Those already available include lasers, LEDs, and TVs with quantum dot technology.

However, there is a problem that can impair the efficiency of devices or appliances using this nanomaterial as an active medium. When light is absorbed by a material, the electrons are promoted to higher energy levels, and when they return to their fundamental state, each one can emit a photon back to the environment. In conventional quantum dots the electron’s return trip to its fundamental state can be disturbed by various quantum phenomena, delaying the emission of light to the exterior.

The imprisonment of electrons in this way, known as the “dark state”, retards the emission of light, in contrast with the path that lets them return quickly to the fundamental state and hence to emit light more efficiently and directly (“bright state”).

This delay can be shorter in a new class of nanomaterial made from perovskite, which is arousing considerable interest among researchers in materials science as a result (read more at: agencia.fapesp.br/32682/).

A study conducted by researchers in the Chemistry and Physics Institutes of the University of Campinas (UNICAMP) in the state of Sao Paulo, Brazil, in collaboration with scientists at the University of Michigan in the United States, made strides in this direction by providing novel insights into the fundamental physics of perovskite quantum dots.

“We used coherent spectroscopy, which enabled us to analyze separately the behavior of the electrons in each nanomaterial in an ensemble of tens of billions of nanomaterials. The study is groundbreaking insofar as it combines a relatively new class of nanomaterials – perovskite – with an entirely novel detection technique,” Lazaro Padilha Junior, principal investigator for the project on the Brazilian side, told Agencia FAPESP.

FAPESP supported the study via a Young Investigator Grant and a Regular Research Grant awarded to Padilha.

“We were able to verify the energy alignment between the bright state [associated with triplets] and the dark state [associated with singlets], indicating how this alignment depends on the size of the nanomaterial. We also made discoveries regarding the interactions between these states, opening up opportunities for the use of these systems in other fields of technology, such as quantum information,” Padilha said.

“”Owing to the crystal structure of perovskite, the level of bright energy divides into three, forming a triplet. This provides various paths for excitation and for the electrons to return to the fundamental state. The most striking result of the study was that by analyzing the lifetimes of each of the three bright states and the characteristics of the signal emitted by the sample we obtained evidence that the dark state is present but located at a higher energy level than two of the three bright states.

This means that when light is shone on the sample the excited electrons are trapped only if they occupy the highest bright level and are then shifted to the dark state. If they occupy the lower bright levels, they return to the fundamental state more efficiently.”

To study how electrons interact with light in these materials, the group used multidimensional coherent spectroscopy (MDCS), in which a burst of ultrashort laser pulses (each lasting about 80 femtoseconds, or 80 quadrillionths of a second) is beamed at a sample of perovskite chilled to minus 269 degrees Celsius.

“The pulses irradiate the sample at tightly controlled intervals. By modifying the intervals and detecting the light emitted by the sample as a function of the interval, we can analyze the electron-light interaction and its dynamics with high temporal precision, mapping the typical interaction times, the energy levels with which they couple, and the interactions with other particles,” Padilha said.

The MDCS technique can be used to analyze billions of nanoparticles at the same time and to distinguish between different families of nanoparticles present in the sample.

The experimental system was developed by a team led by Steven Cundiff, principal investigator for the study at the University of Michigan. Some of the measurements were made by Diogo Almeida, a former member of Cundiff’s team and now at UNICAMP’s ultrafast spectroscopy laboratory with a postdoctoral fellowship from FAPESP under Padilha’s supervision.

Quantum dots were synthesized by Luiz Gustavo Bonato, a PhD candidate at UNICAMP’s Chemistry Institute. “The care Bonato took in preparing the quantum dots and his protocol were fundamentally important, as evidenced by their quality and size, and by the properties of the nanometric material,” said Ana Flavia Nogueira, co-principal investigator for the study in Brazil. Nogueira is a professor at the Chemistry Institute (IQ-UNICAMP) and principal investigator for Research Division 1 at the Center for Innovation in New Energies (CINE), an Engineering Research Center (ERC) established by FAPESP and Shell.

“”The results obtained are very important since knowledge of the optical properties of the material and how its electrons behave opens up opportunities for the development of new technologies in semiconductor optics and electronics. The incorporation of perovskite is highly likely to be the most distinctive feature of the next generation of television sets,” Nogueira said.

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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