Solar Energy

Light flexible and radiation resistant organic solar cells for space

Published

2 months ago

January 13, 2025

sarosh

Light flexible and radiation resistant organic solar cells for space

by Clarence Oxford

Los Angeles CA (SPX) Jan 13, 2025

Radiation tests suggest that carbon-based organic solar cells could surpass traditional silicon and gallium arsenide cells in efficiency and durability for space applications, according to a University of Michigan study.

Previous research primarily examined how radiation affected the energy conversion efficiency of organic solar cells. This new study delved into molecular-level changes that degrade performance.

“Silicon semiconductors aren’t stable in space because of proton irradiation coming from the sun,” explained Yongxi Li, first author of the study and a former U-M associate research scientist in electrical and computer engineering. “We tested organic photovoltaics with protons because they are considered the most damaging particles in space for electronic materials.”

While gallium arsenide is favored for its efficiency and resilience against proton damage, its weight, inflexibility, and high cost pose challenges. Organic solar cells, on the other hand, are lightweight, flexible, and potentially more affordable. This study is part of ongoing efforts to assess the reliability of organic materials for critical space missions.

Organic solar cells built from small molecules demonstrated strong resistance to proton radiation, showing no performance degradation after simulated exposure equivalent to three years in space. In contrast, cells made with polymer-based materials lost half their efficiency over the same period.

“We found that protons cleave some of the side chains, and that leaves an electron trap that degrades solar cell performance,” said Stephen Forrest, the Peter A. Franken Distinguished University Professor of Engineering at U-M and lead corresponding author. These traps capture electrons generated by light, reducing the flow of electricity to the electrodes.

Forrest noted that heating the solar cells, a process known as thermal annealing, can repair the damage by restoring broken molecular bonds. “You can heal this by thermal annealing, or heating the solar cell. But we might find ways to fill the traps with other atoms, eliminating this problem,” he added.

The study suggests that solar cells exposed to sunlight in space could self-repair at temperatures around 100C. However, questions about the effectiveness of this self-healing in a vacuum and its reliability for extended missions remain. The team is also exploring ways to design materials that prevent the formation of electron traps altogether.

Li, now an incoming associate professor of advanced materials and manufacturing at Nanjing University in China, plans to further investigate these avenues.

The research received funding from Universal Display Corp and the U.S. Office of Naval Research. The devices were fabricated at the Lurie Nanofabrication Facility, tested with proton beams at the Michigan Ion Beam Laboratory, and analyzed at the Michigan Center for Materials Characterization.

U-M Innovation Partnerships is assisting the team in patent applications, with Universal Display licensing the technology and filing additional patents. Forrest holds a financial interest in Universal Display Corp.

Research Report:Radiation hardness of organic photovoltaics

Source link

Solar Energy

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

Published

4 hours ago

March 14, 2025

sarosh

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

Source link

Solar Energy

Groundbreaking Discovery Links Small Polaron Effect to Enhanced Spin Lifetime in 2D Lead Halide Perovskites

Published

4 hours ago

March 14, 2025

sarosh

Groundbreaking Discovery Links Small Polaron Effect to Enhanced Spin Lifetime in 2D Lead Halide Perovskites

by Simon Mansfield

Sydney, Australia (SPX) Mar 14, 2025

Two-dimensional lead halide perovskites have emerged as highly promising materials for optoelectronic applications due to their superior carrier transport and defect tolerance. However, a comprehensive understanding of charge carrier dynamics in these materials has remained elusive, primarily due to their inherently soft polar lattice and pronounced electron-phonon interactions. While extensive studies have characterized charge behavior in bulk three-dimensional perovskites, the unique carrier dynamics of their two-dimensional counterparts have yet to be fully deciphered.

A recent study employed advanced transient spectroscopic methods combined with theoretical modeling to uncover the presence of small polarons in Dion-Jacobson phase 2D perovskites, particularly in the compound (4AMP)PbI4. Researchers determined that strong charge-lattice coupling induces a substantial deformation potential of 123 eV-approximately 30 times greater than those typically observed in conventional 2D and 3D perovskites. This extraordinary interaction significantly influences carrier dynamics within the material.

Utilizing optical Kerr spectroscopy, the research team identified extended polarization response times at room temperature, surpassing 600 ps. The study attributes this prolonged response to the formation of small polarons, which span roughly two-unit cells in size due to the lattice distortions present in the material. Additional investigations involving temperature-dependent phonon studies, spin relaxation analyses, and X-ray diffraction further substantiated the presence of these small polarons. These findings highlight their role in modifying excitonic Coulomb exchange interactions, leading to an up to tenfold increase in spin lifetime.

Implications for Optoelectronic Advancements

This discovery holds considerable promise for the future of optoelectronic device engineering. By elucidating the impact of small polaron formation on spin dynamics, researchers can refine 2D perovskite materials to achieve superior carrier mobility, extended spin lifetimes, and enhanced energy conversion efficiency. Such improvements could accelerate the development of next-generation solar cells, photodetectors, and spintronic devices.

The study also paves the way for tailoring charge-lattice interactions through controlled deformation potential tuning, potentially optimizing perovskite-based device performance. Future investigations may delve deeper into fine-tuning polaronic effects to further capitalize on their benefits in commercial applications.

Future Prospects

This research provides direct evidence of small polaron formation in Dion-Jacobson phase 2D perovskites, underscoring the critical influence of lattice interactions on spin dynamics and optoelectronic efficiency. Continued exploration of these mechanisms is expected to drive the development of novel materials that could redefine perovskite-based optoelectronics. These findings mark a significant step toward realizing energy-efficient, high-performance electronic and photonic devices.

Research Report:Giant deformation potential induced small polaron effect in Dion-Jacobson two-dimensional lead halide perovskites

Source link

Solar Energy

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

Published

1 day ago

March 13, 2025

sarosh

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