Solar Energy

Lithuanian researchers advance solar cell technology

Published

10 months ago

May 17, 2024

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Lithuanian researchers advance solar cell technology

by Robert Schreiber

Berlin, Germany (SPX) May 16, 2024

Researchers from Kaunas University of Technology (KTU), Lithuania, who previously developed high-efficiency solar cells, have expanded their invention. The self-assembled monolayers can now be applied in both inverted and regular structure perovskite solar cells.

Self-assembling molecules form a single-molecule-thick layer, acting as an electron-transporting layer in solar cells.

“The molecules that make up these monolayers, like a clever glue, coat the surface of the constructed devices with a thin one molecule thick layer. And this is not random, they don’t stick wherever they go, but attach themselves by chemical bonds only where they are in contact with conductive metal oxide,” explained Tadas Malinauskas, Professor at KTU’s Faculty of Chemical Technology and one of the inventors of the new technology.

According to Malinauskas, creating such a layer is a simple and material-efficient process that requires a glass substrate with an electrically conductive metal oxide layer to be immersed in or sprayed with a highly diluted solution of the compound. The self-assembling molecules attach only to the metal oxide surface, with non-adhering molecules being washed away. This creates a thin layer precisely where it is needed.

KTU researchers have been synthesizing and studying charge-transporting organic materials for several years, focusing previously on molecules for positive charge transfer in perovskite solar cells.

“We can already say with confidence that these molecules have given a major boost to the development of the next generation solar cells. So, our next step is quite logical: to develop analogous molecules that can carry negative charges, and to apply these materials in perovskite solar cells,” said Vytautas Getautis, professor at the KTU Faculty of Chemical Technology and head of the research group.

Although it is a very thin layer, its role in solar cells is critical. Malinauskas compared its function to that of an automatic gate in the subway, allowing only one type of charge to pass through towards the electrode, thereby increasing solar cell efficiency.

Perovskite solar cell structures vary in layer sequence. In the regular structure, a negative charge transporting layer is formed on a transparent substrate, followed by light-absorbing and positive charge transporting layers. In the inverted structure, the positive and negative charge transport layers are swapped.

KTU PhD student Lauryna Monika Svirskaite explained that the main difference between the two structures lies in their application areas. The regular structure is used for studying low-cost, easier-manufactured but less efficient solar cells, while the inverted architecture allows for more efficient combined devices, known as tandem devices.

Currently, as both structures are being intensively researched, KTU scientists believe that their new invention is as significant and promising as their previous developments.

The new invention resulted from collaboration with scientists from King Abdullah University of Science and Technology (KAUST).

“We, KTU chemists, were responsible for the development, improvement, and optimisation of the materials and coating technology, while our colleagues from Saudi Arabia investigated the performance of it in solar cells,” revealed Malinauskas.

Greta Zekiene, head of Intellectual Property Management at KTU’s National Innovation and Entrepreneurship Centre (NIEC), said the demand for this invention is surprisingly high. Interest in the invention’s industrial use preceded the patent application filing.

“A Japanese company, with whom we already have several licences for inventions in this field, immediately expressed the interest to have the innovation in their product portfolio. They were waiting for us to prepare a patent application. The process of negotiating a licence agreement started right away,” said Zekiene.

She emphasized that obtaining a patent is not necessary for commercializing an invention, as it depends on the individual case. Commercialization can occur at any time if a business declares its intention to license or take over all the property rights.

Zekiene added that inventions in the field of solar cells made by the Synthesis of Organic Semiconductors research group are the strongest in KTU’s patent portfolio and receive significant interest from businesses. “We feel proud and acknowledged when companies want to start using the inventions as soon as possible,” she said.

Research Report:Nonfullerene Self-Assembled Monolayers As Electron-Selective Contacts for n-i-p Perovskite Solar Cells

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Solar Energy

Identifying Key Organic-Inorganic Interaction Sites for Enhanced Emission in Hybrid Perovskites via Pressure Engineering

Published

1 hour ago

March 14, 2025

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Identifying Key Organic-Inorganic Interaction Sites for Enhanced Emission in Hybrid Perovskites via Pressure Engineering

by Simon Mansfield

Sydney, Australia (SPX) Mar 14, 2025

A research team from Jilin University has developed a new approach using pressure engineering to pinpoint organic-inorganic interaction sites in non-hydrogen-bonded hybrid metal perovskites. This innovative method provides valuable insight into the photophysical mechanisms governing hybrid perovskites and offers guidance for designing materials with tailored optical properties.

“Previous research has primarily focused on the role of hydrogen bonding in shaping the photophysical properties of hybrid perovskites,” explained Guanjun Xiao, the study’s lead researcher. “However, the lack of investigation into the interaction mechanisms of non-hydrogen-bonded hybrid perovskites has hindered precise material design for targeted applications.”

By employing high-pressure techniques, Xiao and his team studied the specific interaction sites within the non-hydrogen-bonded hybrid perovskite (DBU)PbBr3. Their findings highlighted that the spatial arrangement of Br-N atomic pairs plays a crucial role in influencing organic-inorganic interactions.

The research was published on September 16 in *Research*, a Science Partner Journal launched by the American Association for the Advancement of Science (AAAS) in collaboration with the China Association for Science and Technology (CAST). Xiao is a professor at the State Key Laboratory of Superhard Materials at Jilin University.

The study involved synthesizing microrod (DBU)PbBr3 using the hot injection method and systematically analyzing its optical and structural properties under high pressure. The researchers observed that the material’s emission exhibited enhancement and a blue shift under pressure, with photoluminescence quantum yield reaching 86.6% at 5.0 GPa. Additionally, photoluminescence lifetime measurements indicated a suppression of non-radiative recombination under pressure.

A significant discovery was the presence of an abnormally enhanced Raman mode in the pressure range where emission enhancement occurred. “This suggests a potential connection between the two phenomena,” Xiao noted. Further analysis identified the Raman mode as being linked to organic-inorganic interactions, likely associated with N-Br bonding.

To deepen their understanding, the team conducted structural evolution studies under pressure, supported by first-principles calculations. They confirmed that the primary determinants of interaction strength were the spatial arrangement of N and Br atoms, including their distance and dihedral angle. A notable isostructural phase transition at 5.5 GPa altered the primary compression direction, initially strengthening organic-inorganic interactions before leading to a subsequent decrease-trends that aligned with observed optical property changes.

“These findings bridge a significant knowledge gap in understanding organic-inorganic interactions in non-hydrogen-bonded hybrid halides, offering valuable design principles for materials with specific optical performance targets,” Xiao stated.

Research Report:Identifying Organic-Inorganic Interaction Sites Toward Emission Enhancement in Non-Hydrogen-Bonded Hybrid Perovskite via Pressure Engineering

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Solar Energy

Cheap and environmentally friendly – the next generation LEDs may soon be here

Published

1 day ago

March 13, 2025

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Cheap and environmentally friendly – the next generation LEDs may soon be here

by Anders Torneholm

Linkoping, Sweden (SPX) Mar 13, 2025

Cost, technical performance and environmental impact – these are the three most important aspects for a new type of LED technology to have a broad commercial impact on society. This has been demonstrated by researchers at Linkoping University in a study published in Nature Sustainability.

“Perovskite LEDs are cheaper and easier to manufacture than traditional LEDs, and they can also produce vibrant and intense colours if used in screens. I’d say that this is the next generation of LED technology,” says Feng Gao, professor of optoelectronics at Linkoping University.

However, for a technological shift to take place, where today’s LEDs are replaced with those based on the material perovskite, more than just technical performance is required. That is why Feng Gao’s research group has collaborated with Professor Olof Hjelm and John Laurence Esguerra, assistant professor at LiU. They specialise in how innovations contributing to environmental sustainability can be introduced to the market.

Together, they have investigated the environmental impact and cost of 18 different perovskite LEDs, knowledge that is currently incomplete. The study was conducted using so-called life cycle assessment and techno-economic assessment.

Such analyses require a clear system definition – that is, what is included and not in terms of cost and environmental impact. Within this framework, what happens from the product being created until it can no longer be used is investigated. The life cycle of the product, from cradle to grave, can be divided into five different phases: raw material production, manufacturing, distribution, use and decommissioning.

“We’d like to avoid the grave. And things get more complicated when you take recycling into account. But here we show that it’s most important to think about the reuse of organic solvents and how raw materials are produced, especially if they are rare materials,” says Olof Hjelm.

One example where the life cycle analysis provides guidance concerns the small amount of toxic lead found in perovskite LEDs. This is currently necessary for the perovskites to be effective. But, according to Olof Hjelm, focusing only on lead is a mistake. There are also many other materials in LEDs, such as gold.

“Gold production is extremely toxic. There are byproducts such as mercury and cyanide. It’s also very energy-consuming,” he says.

The greatest environmental gain would instead be achieved by replacing gold with copper, aluminium or nickel, while maintaining the small amount of lead needed for the LED to function optimally.

The researchers have concluded that perovskite LEDs have great potential for commercialisation in the long term. Maybe they can even replace today’s LEDs, thanks to lower costs and less environmental impact. The big issue is longevity. However, the development of perovskite LEDs is accelerating and their life expectancy is increasing. The researchers believe that it needs to reach about 10,000 hours for a positive environmental impact, something they think is achievable. Today, the best perovskite LEDs last for hundreds of hours.

Muyi Zhang, PhD student at the Department of Physics, Chemistry and Biology at LiU, says that much of the research focus so far is on increasing the technical performance of LED, something he believes will change.

“We want what we develop to be used in the real world. But then, we as researchers need to broaden our perspective. If a product has high technical performance but is expensive and isn’t environmentally sustainable, it may not be highly competitive in the market. That mindset will increasingly come to guide our research.”

Research Report:Towards sustainable perovskite light-emitting diodes

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Solar Energy

Making solar projects cheaper and faster with portable factories

Published

1 day ago

March 13, 2025

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Making solar projects cheaper and faster with portable factories

by Zach Winn | MIT News

Boston MA (SPX) Mar 13, 2025

As the price of solar panels has plummeted in recent decades, installation costs have taken up a greater share of the technology’s overall price tag. The long installation process for solar farms is also emerging as a key bottleneck in the deployment of solar energy.

Now the startup Charge Robotics is developing solar installation factories to speed up the process of building large-scale solar farms. The company’s factories are shipped to the site of utility solar projects, where equipment including tracks, mounting brackets, and panels are fed into the system and automatically assembled. A robotic vehicle autonomously puts the finished product – which amounts to a completed section of solar farm – in its final place.

“We think of this as the Henry Ford moment for solar,” says CEO Banks Hunter ’15, who founded Charge Robotics with fellow MIT alumnus Max Justicz ’17. “We’re going from a very bespoke, hands on, manual installation process to something much more streamlined and set up for mass manufacturing. There are all kinds of benefits that come along with that, including consistency, quality, speed, cost, and safety.”

Last year, solar energy accounted for 81 percent of new electric capacity in the U.S., and Hunter and Justicz see their factories as necessary for continued acceleration in the industry.

The founders say they were met with skepticism when they first unveiled their plans. But in the beginning of last year, they deployed a prototype system that successfully built a solar farm with SOLV Energy, one of the largest solar installers in the U.S. Now, Charge has raised $22 million for its first commercial deployments later this year.

From surgical robots to solar robots

While majoring in mechanical engineering at MIT, Hunter found plenty of excuses to build things. One such excuse was Course 2.009 (Product Engineering Processes), where he and his classmates built a smart watch for communication in remote areas.

After graduation, Hunter worked for the MIT alumni-founded startups Shaper Tools and Vicarious Surgical. Vicarious Surgical is a medical robotics company that has raised more than $450 million to date. Hunter was the second employee and worked there for five years.

“A lot of really hands on, project-based classes at MIT translated directly into my first roles coming out of school and set me up to be very independent and run large engineering projects,” Hunter says, “Course 2.009, in particular, was a big launch point for me. The founders of Vicarious Surgical got in touch with me through the 2.009 network.”

As early as 2017, Hunter and Justicz, who majored in mechanical engineering and computer science, had discussed starting a company together. But they had to decide where to apply their broad engineering and product skillsets.

“Both of us care a lot about climate change. We see climate change as the biggest problem impacting the greatest number of people on the planet,” Hunter says. “Our mentality was if we can build anything, we might as well build something that really matters.”

In the process of cold calling hundreds of people in the energy industry, the founders decided solar was the future of energy production because its price was decreasing so quickly.

“It’s becoming cheaper faster than any other form of energy production in human history,” Hunter says.

When the founders began visiting construction sites for the large, utility-scale solar farms that make up the bulk of energy generation, it wasn’t hard to find the bottlenecks. The first site they traveled to was in the Mojave Desert in California. Hunter describes it as a massive dust bowl where thousands of workers spent months repeating tasks like moving material and assembling the same parts, over and over again.

“The site had something like 2 million panels on it, and every single one was assembled and fastened the same way by hand,” Hunter says. “Max and I thought it was insane. There’s no way that can scale to transform the energy grid in a short window of time.”

Hunter says he heard from each of the largest solar companies in the U.S. that their biggest limitation for scaling was labor shortages. The problem was slowing growth and killing projects.

Hunter and Justicz founded Charge Robotics in 2021 to break through that bottleneck. Their first step was to order utility solar parts and assemble them by hand in their backyards.

“From there, we came up with this portable assembly line that we could ship out to construction sites and then feed in the entire solar system, including the steel tracks, mounting brackets, fasteners, and the solar panels,” Hunter explains. “The assembly line robotically assembles all those pieces to produce completed solar bays, which are chunks of a solar farm.”

Each bay represents a 40-foot piece of the solar farm and weighs about 800 pounds. A robotic vehicle brings it to its final location in the field. Hunter says Charge’s system automates all mechanical installation except for the process of pile driving the first metal stakes into the ground.

Charge’s assembly lines also have machine-vision systems that scan each part to ensure quality, and the systems work with the most common solar parts and panel sizes.

From pilot to product

When the founders started pitching their plans to investors and construction companies, people didn’t believe it was possible.

“The initial feedback was basically, ‘This will never work,'” Hunter says. “But as soon as we took our first system out into the field and people saw it operating, they got much more excited and started believing it was real.”

Since that first deployment, Charge’s team has been making its system faster and easier to operate. The company plans to set up its factories at project sites and run them in partnership with solar construction companies. The factories could even run alongside human workers.

“With our system, people are operating robotic equipment remotely rather than putting in the screws themselves,” Hunter explains. “We can essentially deliver the assembled solar to customers. Their only responsibility is to deliver the materials and parts on big pallets that we feed into our system.”

Hunter says multiple factories could be deployed at the same site and could also operate 24/7 to dramatically speed up projects.

“We are hitting the limits of solar growth because these companies don’t have enough people,” Hunter says. “We can build much bigger sites much faster with the same number of people by just shipping out more of our factories. It’s a fundamentally new way of scaling solar energy.”

Video: “Charge Robotics Sunrise fully autonomous solar construction system”