Solar Energy
Shedding light on perovskite films
Photovoltaics decisively contributes to sustainable energy supply. The efficiency of solar cells in directly converting light energy into electrical energy depends on the material used. Metal-halide perovskites are considered very promising materials for solar cells of the next generation. With these semiconductors named after their special crystal structure, a considerable increase in efficiency was achieved in the past years.
Meanwhile, perovskite solar cells have reached an efficiency of up to 25.5 percent, which is quite close to that of silicon solar cells that are presently dominating the market. Moreover, the materials needed for perovskite solar cells are rather abundant.
The solar cells can be produced easily and at low cost and they can be used for various applications. The theoretically achievable efficiency of perovskite solar cells is about 30.5 percent.
To approach this value, optoelectronic quality of perovskite semiconductors must be further increased. In principle, materials suited for photovoltaics are expected to not only absorb light, but to also emit it efficiently. This process is known as photoluminescence. The corresponding parameter, photoluminescence quantum efficiency, is perfectly suited to determine the quality of perovskite semiconductors.
Together with scientists from the Center for Advanced Materials (CAM) of Heidelberg University and the Technical University of Dresden, researchers of KIT’s Institute of Microstructure Technology (IMT) and Light Technology Institute (LTI) have now developed a model, by means of which photoluminescence quantum efficiency of perovskite films can be determined reliably and exactly for the first time. Their results are reported in Matter.
Materials Have More Optimization Potentials than Assumed
“With the help of our model, photoluminescence quantum efficiency under solar irradiation can be determined far more precisely,” says Dr. Paul Fassl from IMT. “Photon recycling is of high importance. This is the share of photons emitted by the perovskite, which is re-absorbed and re-emitted in the thin films.”
The researchers applied their model to methylammonium lead triiodide (CH3NH3PbI3), one of the perovskites of highest photoluminescence quantum efficiency. So far, it has been estimated to amount to about 90 percent.
Model calculations, however, revealed that it is about 78 percent. The scientists explain that previous estimations did not adequately consider the effect of light scattering and, hence, underestimated the probability of photons – the quantums of light energy – leaving the film before they are re-absorbed.
“Our results show that the potential for optimization of these materials is far higher than assumed,” says Dr. Ulrich W. Paetzold, Head of the Advanced Optics and Materials for Next Generation Photovoltaics Group of IMT. The team offers an open-source application based on the model, by means of which photoluminescence quantum efficiencies of various perovskite materials can be calculated.
800-mn-euro battery factory to be built in Finland
by AFP Staff Writers
Helsinki (AFP) Mar 20, 2025
A Chinese-Finnish company announced Thursday it would begin building a battery materials plant in Finland in April, the first of its kind in the Nordic country.
The plant will produce cathode active material, a key component in lithium-ion batteries used in electric vehicles and for energy storage, said Easpring Finland New Materials, a company co-owned by Finnish Minerals Group and Beijing Easpring Material Technology.
It said the investment was worth 800 million euros ($868 million).
The announcement came one week after a bankruptcy filing by Swedish battery maker Northvolt, which had planned to develop cathode production but dropped those plans to focus on battery cell production as it fought for survival.
Easpring Finland New Materials said commercial production was expected to begin in 2027.
The plant, to be located in Kotka in southeast Finland, will initially produce 60,000 tonnes of cathode active material annually.
At full production capacity, it could supply cathode material for the production of around 750,000 electric vehicles annually, the company said.
Matti Hietanen, the chief executive of Finnish Minerals Group, said the investment created an “entirely new kind of industry in Finland related to the production of lithium-ion batteries” and represented a European “spearhead project for the industry.”
The new plant will employ 270 people and an area of around 80 hectares had been reserved for its construction.
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Nanocellulose infused with red onion extract shields solar cells from UV degradation
by Robert Schreiber
Berlin, Germany (SPX) Mar 20, 2025
Researchers at the University of Turku in Finland have developed a bio-based film that provides high-performance UV protection for solar cells, utilizing nanocellulose treated with red onion skin extract. This marks the first comparative study of how various bio-derived UV filters perform over time.
Solar cells, susceptible to damage from ultraviolet radiation, are typically shielded by petroleum-derived films such as polyvinyl fluoride (PVF) or polyethylene terephthalate (PET). In an effort to reduce reliance on fossil fuels, researchers are exploring sustainable alternatives like nanocellulose, a material made by refining cellulose into nanoscale fibers that can be customized for UV blocking capabilities.
The study, conducted in collaboration with Aalto University in Finland and Wageningen University in the Netherlands, revealed that nanocellulose films dyed with red onion extract blocked 99.9% of UV rays up to 400 nanometres. This performance surpassed that of commercial PET-based filters, which served as a benchmark in the research.
“Nanocellulose films treated with red onion dye are a promising option in applications where the protective material should be bio-based,” stated Doctoral Researcher Rustem Nizamov from the University of Turku.
Researchers evaluated four types of nanocellulose films enhanced with red onion extract, lignin, or iron ions, all known for their UV-filtering properties. Among them, the film incorporating red onion extract demonstrated the most effective UV shielding.
Effective UV protection must be balanced with the ability to transmit visible and near-infrared light, essential for solar energy conversion. While materials like lignin excel in UV absorption, their dark hue hinders transparency. In contrast, the red onion-based film achieved over 80% light transmission at wavelengths between 650 and 1,100 nanometres, maintaining this level over extended testing.
To simulate prolonged outdoor use, the films were exposed to artificial light for 1,000 hours, equating to roughly one year of natural sunlight in central Europe. Researchers tracked changes in the films and solar cells through digital imaging.
“The study emphasised the importance of long-term testing for UV filters, as the UV protection and light transmittance of the other bio-based filters changed significantly over time. For example, the films treated with iron ions had good initial transmittance which reduced after aging,” tells Nizamov.
Tests focused on dye-sensitised solar cells, which are particularly prone to UV-induced deterioration. The findings also have broader implications for other solar technologies like perovskite and organic photovoltaics, where bio-based UV filters could play a crucial role.
“These results are also relevant for the UV protection of other types of solar cells, including perovskite and organic photovoltaics, as well as any application where the use of a bio-based UV filter is paramount,” Nizamov says.
Looking ahead, the researchers aim to create biodegradable solar cells that could serve as power sources in applications such as food packaging sensors.
“The forest industry is interested in developing new high-grade products. In the field of electronics, these may also be components for solar cells,” noted Kati Miettunen, Professor in Materials Engineering.
The University of Turku’s Solar Energy Materials and Systems (SEMS) group is exploring ways to integrate solar technologies into broader energy systems.
This work was part of the BioEST project, supported by the Research Council of Finland.
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Space Solar teams with MagDrive to boost in-orbit solar power systems
by Sophie Jenkins
London, UK (SPX) Mar 20, 2025
Space Solar, a leading force in the field of space-based solar power (SBSP), has formed a strategic alliance with UK propulsion technology company Magdrive to enhance the deployment of large-scale infrastructure in orbit. The agreement, unveiled during the Farnborough International Space Show (FISS), is formalized under the Space Propulsion and Infrastructure Innovation Initiative (SPI3), reflecting a concerted push to realize space-driven clean energy.
SPI3 is designed to help fulfil the UK’s long-term goal of producing scalable, sustainable energy directly from space. By integrating Magdrive’s advanced propulsion systems, the initiative addresses the complex challenge of transporting, assembling, and managing substantial SBSP infrastructure in orbit.
Space Solar plans to launch its first 30-megawatt SBSP platform within five years, and success hinges on the ability to control and maintain massive solar satellite structures. Magdrive’s propulsion solutions are poised to support upcoming demonstration missions by enabling essential orbital maneuvers, satellite assembly, and shape optimization.
“Innovation in propulsion is essential to making large-scale space infrastructure a reality,” said Sam Adlen, Co-CEO of Space Solar. “Space Solar and Magdrive share a vision of advancing sustainable space operations that benefit earth, and this collaboration will pave the way for new propulsion solutions that will be indispensable for space-based solar power and other large scale space infrastructure.”
This partnership is also set to strengthen the UK’s space sector by stimulating high-value job creation and technological advancement. It highlights the country’s dedication to leading innovation at the intersection of clean energy and aerospace.
As part of SPI3, both companies will collaborate on refining propulsion specifications tailored to SBSP systems and identify additional applications for these technologies within the broader context of UK-led space initiatives. The cooperation is a key step towards expanding the UK’s footprint in the global space economy and unlocking emerging opportunities in space-based energy markets.
“We’re excited to work with Space Solar, they’re building the future of space energy and infrastructure on a scale never seen before. By working together we’ll be propelling the space industry towards enabling sustainable life on earth. Here’s to the new space age!” said Mark Stokes, CEO, MagDrive.
United by a vision to deliver scalable energy solutions from space, Space Solar and Magdrive’s agreement represents a pivotal move toward the commercialization of SBSP. As Space Solar progresses toward critical mission milestones, incorporating Magdrive’s propulsion technology will bring the reality of space-derived clean energy closer than ever.
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