Solar Energy

Toward new solar cells with active learning

Published

3 years ago

April 25, 2021

sarosh

Toward new solar cells with active learning

How can I prepare myself for something I do not yet know? Scientists from the Fritz Haber Institute in Berlin and from the Technical University of Munich have addressed this almost philosophical question in the context of machine learning. Learning is no more than drawing on prior experience. In order to deal with a new situation, one needs to have dealt with roughly similar situations before.

In machine learning, this correspondingly means that a learning algorithm needs to have been exposed to roughly similar data. But what can we do if there is a nearly infinite amount of possibilities so that it is simply impossible to generate data that covers all situations?

This problem comes up a lot when dealing with an endless number of possible candidate molecules. Organic semiconductors enable important future technologies such as portable solar cells or rollable displays.

For such applications, improved organic molecules – which make up these materials – need to be discovered. Tasks of this nature are increasingly using methods of machine learning, while training on data from computer simulations or experiments.

The number of potentially possible small organic molecules is, however, estimated to be on the order of 1033. This overwhelming number of possibilities makes it practically impossible to generate enough data to reflect such a large material diversity. In addition, many of those molecules are not even suitable for organic semiconductors. One is essentially looking for the proverbial needle in a haystack.

In their work published recently in Nature Communications the team around Prof. Karsten Reuter, Director of the Theory Department at the Fritz-Haber-Institute, addressed this problem using so-called active learning. Instead of learning from existing data, the machine learning algorithm iteratively decides for itself which data it actually needs to learn about the problem.

The scientists first carry out simulations on a few smaller molecules, and obtain data related to the molecules’ electrical conductivity – a measure of their usefulness when looking at possible solar cell materials. Based on this data, the algorithm decides if small modifications to these molecules could already lead to useful properties or whether it is uncertain due to a lack of similar data.

In both cases, it automatically requests new simulations, improves itself through the newly generated data, considers new molecules, and goes on to repeat this procedure.

In their work, the scientists show how new and promising molecules can efficiently be identified this way, while the algorithm continues its exploration into the vast molecular space, even now, at this very moment. Every week new molecules are being proposed that could usher in the next generation of solar cells and the algorithm just keeps getting better and better.

Source link

Solar Energy

New Layered Perovskite Structure Explored for Enhanced Optical Properties

Published

17 hours ago

April 19, 2024

sarosh

New Layered Perovskite Structure Explored for Enhanced Optical Properties

by Riko Seibo

Tokyo, Japan (SPX) Apr 19, 2024

Perovskites are critically important in the field of materials science due to their distinct and varied properties arising from their unique crystal structure. These properties have potential revolutionary applications in advanced technology areas. A method to harness these properties involves precise manipulation of defects within the perovskite structure, such as missing atoms or substituting one type of atom for another.

In the realm of oxide chemistry, it’s well-established that such defects in oxides can self-organize within the crystal structure when they reach a certain threshold, leading to enhanced material properties. While this phenomenon of defect ordering is well-documented in perovskite oxides, it has not been as prevalent in hybrid halide perovskites, which consist of an organic component, a metal, and a halogen.

A recent study highlighted in ACS Materials Letters reveals findings by Associate Professor Takafumi Yamamoto and his team at Tokyo Institute of Technology, who discovered a novel defect-ordered layered halide perovskite. The research builds on earlier work where the introduction of thiocyanate ions (SCN-) into the FAPbI3 lattice led to structured defect formations. Dr. Yamamoto suggests, “Increasing the SCN concentration might amplify the formation of these defect structures, similar to those observed in vacancy-ordered oxide perovskites.”

The research involved synthesizing FAPbI3 in powder and crystal forms, using specific ratios of SCN-. When a high enough SCN- ratio was used, the resulting perovskite was FA4Pb2I7.5(SCN)0.5. This compound displayed organized defects throughout its layers-more so than its predecessor, FA6Pb4I13.5(SCN)0.5, where fewer defects were organized.

The study identifies this material as part of a ‘homologous series’-a sequence where systematic alterations to the chemical formula yield predictable changes in properties, here observed as variations in the optical bandgap correlated with defect concentration.

“This marks the first instance of a homologous series based on defect ordering in hybrid organic-inorganic perovskites,” notes Dr. Yamamoto. “Our findings set a foundational strategy for manipulating defect structures to adjust the optical properties of perovskites, offering a promising avenue for materials science innovation.”

The implications of this research are significant, potentially paving the way for new perovskite materials with tailored properties for future technological applications.

Research Report:FA4Pb2I7.5(SCN)0.5: n = 3 Member of Perovskite Homologous Series FAn+1Pbn-1I3n-1.5(SCN)0.5 with Organized Defects

Source link

Solar Energy

Solar energy adoption challenges in rural Ethiopia

Published

18 hours ago

April 19, 2024

sarosh

Solar energy adoption challenges in rural Ethiopia

by Clarence Oxford

Los Angeles CA (SPX) Apr 19, 2024

Despite decreasing costs and increasing accessibility of solar home systems, significant obstacles hinder their widespread use in remote areas of developing countries, such as Ethiopia, where they could greatly improve health and education.

Inexpensive, yet uncertified and inferior solar panels, along with limited government engagement in rural energy transition, impede access to dependable electricity for these communities.

When homes do incorporate solar energy, it replaces harmful kerosene lamps, offering a healthier, eco-friendly alternative and enabling children to study after dark.

“Understanding the dynamics of renewable energy adoption in rural sectors of the Global South is crucial,” said Yujin Lee, a doctoral student at Cornell University’s Department of City and Regional Planning and first author of a related study in Energy Policy.

Chuan Liao, the study’s senior author and assistant professor in the Department of Global Development at Cornell, emphasized, “The global shift to renewable and clean energy sources must include remote and rural populations in the developing world.”

Ethiopia’s national electrification strategy aims to power all homes within 25 kilometers of the grid by 2030. Those further away are slated for long-term off-grid solutions.

However, the prevalence of low-quality solar panels, which often fail and contribute to environmental waste, poses a barrier to adoption. Additionally, the infrequency of government visits to rural, off-grid or road-less villages leads to misinformed policies.

“Government reports often do not reflect the true situation in rural areas,” noted Lee, who found actual solar adoption rates to be markedly lower than official claims.

Lee advocates for increased governmental presence in rural communities, enhanced public engagement in energy management, and improved communication between governments, private sectors, international organizations, and end-users to support sustainable energy solutions.

Source link

Solar Energy

The role of Floating Solar in achieving Africa’s energy targets as an alternative to dams

Published

19 hours ago

April 19, 2024

sarosh

The role of Floating Solar in achieving Africa’s energy targets as an alternative to dams

by Hugo Ritmico

Madrid, Spain (SPX) Apr 19, 2024

Researchers from Politecnico di Milano have identified floating solar photovoltaics (FPV) as a viable alternative to traditional hydropower in meeting Africa’s energy goals, according to a new study published in Nature Energy. The study shows that FPV installed at existing major reservoirs could generate 20-100% of the electricity projected from planned hydropower dams across Africa.

The research, conducted using a comprehensive energy planning model, reveals that FPV is not only cost-effective compared to other renewable resources but also plays a crucial role in Africa’s energy future. “Floating solar has emerged as cost-competitive and could potentially eliminate the need for many new dams,” stated Wyatt Arnold, the lead author of the study.

A detailed analysis of the transboundary Zambezi watercourse indicated that capital investments for new dams could be more effectively utilized by constructing fewer reservoirs and augmenting them with floating solar panels. This strategy could decrease interannual variability in electricity supply by 12% and enhance resilience against long-term droughts exacerbated by climate change.

“Adopting floating solar can provide developing economies with a stable energy supply less susceptible to hydrological changes,” explained Prof. Andrea Castelletti. “Additionally, it mitigates adverse effects on downstream communities and river ecosystems compared to new dam projects.”

The study also underscores the significance of integrated resource planning and the need to consider transboundary effects in sustainable development. It promotes multisector modeling that integrates energy, agriculture, environmental protection, and economic growth within river basins.

Prof. Matteo Giuliani noted, “The strategic deployment of floating solar might outweigh potential drawbacks on reservoir uses like fishing or recreation. Yet, ongoing enhancements in FPV technology and effective planning are essential for its responsible implementation.”

While floating solar offers substantial environmental benefits, the study acknowledges challenges in technology and social acceptance that may limit its deployment. Nevertheless, these challenges are likely to be less impactful than the negative consequences of new hydropower projects, which can disrupt river ecologies, displace populations, and increase regional conflicts over water use.

Research Report:Floating solar emerges as a sustainable energy solution for Africa’s future