Solar Energy

Starting small to answer the big questions about photosynthesis

Published

4 years ago

March 17, 2021

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Starting small to answer the big questions about photosynthesis

New scientific techniques are revealing the intricate role that proteins play in photosynthesis.

Despite being discovered almost 300 years ago, photosynthesis still holds many unanswered questions for science, particularly the way that proteins organise themselves to convert sunlight into chemical energy and at the same time, protect plants from too much sunlight.

Now a collaboration between researchers at the University of Leeds and Kobe University in Japan is developing a novel approach to the investigation of photosynthesis.

Using hybrid membranes that mimic natural plant membranes and advanced microscopes, they are opening photosynthesis to nanoscale investigation – the study of life at less than one billionth of a metre – to reveal the behaviour of individual protein molecules.

Dr Peter Adams, Associate Professor in the School of Physics and Astronomy at the University of Leeds, who supervised the research, said: “For many decades scientists have been developing an understanding of photosynthesis in terms of the biology of whole plants. This research is tackling it at the molecular level and the way proteins interact.

“A greater understanding of photosynthesis will benefit humankind. It will help scientists identify new ways to protect and boost crop yields, as well as inspire technologists to develop new solar-powered materials and components.”

The findings are published in the academic journal Small.

Photosynthesis happens when photons or packets of light energy cause pigments inside light-harvesting proteins to become excited. The way that these proteins arrange themselves determines how the energy is transferred to other molecules.

It is a complex system that plays out across many different pigments, proteins, and layers of light-harvesting membranes within the plant. Together, it regulates energy absorption, transfer, and the conversion of this energy into other useful forms.

To understand this intricate process, scientists have been using a technique called atomic force microscopy, which is a device capable of revealing components of a membrane that are a few nanometres in size.

The difficulty is that natural plant membranes are very fragile and can be damaged by atomic force microscopy.

But last year, the researchers at Kobe University announced that they had developed a hybrid membrane made up of natural plant material and synthetic lipids that would act as a substitute for a natural plant membrane – and crucially, is more stable when placed in an atomic force microscope.

The team at the University of Leeds used the hybrid membrane and subjected it to atomic force microscopy and another advanced visualisation technique called fluorescence lifetime imaging microscopy, or FLIM.

PhD researcher Sophie Meredith, also from the School of Physics at the University of Leeds, is the lead author in the paper. She said: “The combination of FLIM and atomic force microscopy allowed us to observe the elements of photosynthesis. It gave us an insight into the dynamic behaviors and interactions that take place.

“What is important is that we can control some of the parameters in the hybrid membrane, so we can isolate and control factors, and that helps with experimental investigation.

“In essence, we now have a ‘testbed’ and a suite of advanced imaging tools that will reveal the sub-molecular working of photosynthesis.”

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Solar Energy

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

Published

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

Published

4 hours ago

March 14, 2025

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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

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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