Solar Energy

Buckyballs on DNA for harvesting light

Published

4 years ago

February 24, 2021

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Organic molecules that capture photons and convert these into electricity have important applications for producing green energy. Light-harvesting complexes need two semiconductors, an electron donor and an acceptor. How well they work is measured by their quantum efficiency, the rate by which photons are converted into electron-hole pairs.

Quantum efficiency is lower than optimal if there is “self-quenching”, where one molecule excited by an incoming photon donates some of its energy to an identical non-excited molecule, yielding two molecules at an intermediate energy state too low to produce an electron-hole pair. But if electron donors and acceptors are better spaced out, self-quenching is limited, so that quantum efficiency improves.

In a new paper in Frontiers in Chemistry, researchers from the Karlsruhe Institute of Technology (KIT) synthesize a novel type of organic light-harvesting supramolecule based on DNA. The double helix of DNA acts as a scaffold to arrange chromophores (i.e. fluorescent dyes) – which function as electron donors – and “buckyballs” – electron acceptors – in three dimensions to avoid self-quenching.

“DNA is an attractive scaffold for building light-harvesting supramolecules: its helical structure, fixed distances between nucleobases, and canonical base pairing precisely control the position of the chromophores. Here we show that carbon buckyballs, bound to modified nucleosides inserted into the DNA helix, greatly enhance the quantum efficiency. We also show that the supramolecule’s 3D structure persists not only in the liquid phase but also in the solid phase, for example in future organic solar cells,” says lead author Dr Hans-Achim Wagenknecht, Professor for Organic Chemistry at Karlsruhe Institute of Technology (KIT).

DNA provides regular structure, like beads on a helical string

As scaffold, Wagenknecht and colleagues used single-stranded DNA, deoxyadenosine (A) and thymine (T) strands 20 nucleotides long. This length was chosen because theory suggests that shorter DNA oligonucleotides wouldn’t assemble orderly, while longer ones wouldn’t be soluble in water.

The chromophores were violet-fluorescent pyrene and red-fluorescent Nile red molecules, each bound noncovalently to a single synthetic uracil (U)-deoxyribose nucleoside. Each nucleoside was base-paired to the DNA scaffold, but the order of pyrenes and Nile reds was left to chance during self-assembly.

For the electron acceptors, Wagenknecht et al. tested two forms of “buckyballs” – also called fullerenes – which are known to have an excellent capacity for “quenching” (accepting electrons). Each buckyball was a hollow globe built from interlocking rings of five or six carbon atoms, for a total of 60 carbons per molecule. The first form of buckyball tested binds nonspecifically to the DNA through electrostatic charges.

The second form – not previously tested as an electron acceptor – was covalently bound via a malonic ester to two flanking U-deoxyribose nucleosides, which allowed it to be base-paired to an A nucleotide on the DNA.

High quantum efficiency, including in solid phase

The researchers confirmed experimentally that the 3D structure of the DNA-based supramolecule persists in solid phase: a crucial requirement for applications in solar cells. To this end, they tested supramolecules with either form of buckyballs as the active layer in a miniature solar cell.

The constructs showed excellent charge separation – the formation of a positive hole and negative electron charge in the chromophore and their acceptance by nearby buckyballs – with either form of buckyball, but especially for the second form.

The authors explain this from the more specific binding, through canonical base-pairing, to the DNA scaffold by the second form, which should result in a smaller distance between buckyball and chromophore. This means that the second form is the better schoice for use in solar cells.

Importantly, the authors also show that the DNA-dye-buckyball supramolecule has strong circular dichroism, that is, it is much more reactive to left- than to right-handed polarized light, due to its complex 3D helical structure – even in the solid phase.

“”I don’t expect that everyone will have solar cells with DNA on their roof soon. But the chirality of DNA will be interesting: DNA-based solar cells might sense circularly polarized light in specialized applications,” concludes Wagenknecht.

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Solar Energy

New system offers early warning of dust storms to protect solar power output

Published

2 days ago

April 16, 2025

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New system offers early warning of dust storms to protect solar power output

by Simon Mansfield

Sydney, Australia (SPX) Apr 10, 2025

A new predictive platform called iDust is poised to transform dust storm forecasting and improve solar energy output in dust-prone regions. Developed by researchers at the Chinese Academy of Sciences, iDust offers high-resolution, fast-turnaround dust forecasts that could help mitigate power losses across solar farms, particularly in arid zones.

The tool was created under the leadership of Dr. Chen Xi from the Institute of Atmospheric Physics and detailed in the Journal of Advances in Modeling Earth Systems (JAMES).

“Dust storms not only block sunlight but also accumulate on solar panels, decreasing their power output.” said Chen, outlining the motivation behind the project. With China’s rapid expansion of solar installations in desert areas, the need for precise and timely dust forecasts has become increasingly urgent to avoid operational disruptions and revenue shortfalls.

Traditional systems like those from the European Centre for Medium-Range Weather Forecasts (ECMWF) often lack the spatial resolution and processing speed needed for optimal solar planning. iDust addresses these limitations by embedding dust-related dynamics directly into its forecast engine. This allows the system to generate forecasts with 10-kilometer resolution-a fourfold improvement over previous models-while maintaining near-parity in computational load. Crucially, iDust can deliver 10-day forecasts within six hours of initial observations.

The effectiveness of iDust was put to the test on April 13, 2024, when it successfully tracked a severe dust storm over Bayannur in northern China. Such storms can distort solar energy projections by as much as 25% if unaccounted for, underscoring the value of integrating dust modeling into energy planning.

Designed for practical deployment, iDust aims to assist solar facility operators and grid managers in optimizing power production and reducing losses due to airborne particulates. As China pushes toward its carbon neutrality goals, innovations like iDust will be central to achieving sustainable energy reliability.

Researchers plan to expand the system for global application, allowing other countries with desert-based solar assets to benefit from enhanced dust forecasting.

Research Report:The Efficient Integration of Dust and Numerical Weather Prediction for Renewable Energy Applications

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Solar Energy

Solar park boom threatens Spain’s centuries-old olive trees

Published

3 days ago

April 15, 2025

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Solar park boom threatens Spain’s centuries-old olive trees

By Rosa SULLEIRO

Lopera, Spain (AFP) April 14, 2025

At his farm in southern Spain, Francisco Campos looked worriedly at a green sea of centuries-old olive trees that he fears will face the axe to make way for a proposed solar park.

“Cutting down olive trees to install solar panels is a crime,” the 64-year-old farmer told AFP in Lopera, a town of whitewashed buildings with 3,600 residents in the sunny southern region of Andalusia, Spain’s olive-growing heartland.

Spain is the world’s top producer of olive oil, but the fertile agricultural land long used by olive producers is now in high demand from power firms looking to install solar farms.

And with nearly 3,000 hours of sunshine per year, Andalusia is one of the Spanish regions with the highest number of solar panels as a renewables boom makes the country a European leader in green energy.

Renewable energy firms such as Greenalia and FRV Arroyadas have requested permission to build multiple solar farms near Lopera, which farmers say will affect up to 1,000 hectares (2,500 acres) of property.

The businesses negotiated agreements to lease the bulk of the land required for their projects but encountered significant opposition from hundreds of small landowners.

This prompted the regional government of Andalusia to announce it will expropriate some land needed for the plants, declaring them to be in “the public interest”.

“Is it in the public interest for them to take my land and give it to a company so that the company can profit? This has no benefit for us,” said Campos.

“Our way of life is going to be destroyed,” he added.

– ‘From our ancestors’ –

Campaigners predict that the eight solar projects planned for the area will require the removal of nearly 100,000 olive trees.

The regional government puts the figure significantly lower, at 13,000.

Local residents anticipated power companies would seek to install solar panels in the area, but they never imagined “they would come and take away your property,” said Rafael Alcala, a spokesman for a platform that represents the solar plants’ opponents.

In support of landowners impacted by the latest round of expropriations, dozens of farmers on tractors — some holding signs that read “We don’t want solar plants” — gathered on a recent morning outside Lopera.

“These lands come from our ancestors. What am I going to leave to my children now?” Maria Josefa Palomo, a 67-year-old pensioner, said at the protest.

Losing 500 hectares of olive groves would wipe out more than two million euros ($2.3 million) in annual revenues, according to local olive oil cooperative La Loperana.

Campaigners say 5,000 olive trees have already been uprooted from land belonging to a farmer in Lopera who signed an agreement with one of the firms behind a solar park. More could follow.

In an effort to stop the projects, opponents have filed lawsuits against the regional government and the companies involved.

– ‘Until the end’ –

Spain generated a record 56.8 percent of its electricity last year from renewable sources such as wind and solar, according to grid operator Red Electrica.

Leveraging on its sunny plains, windy hillsides and fast-flowing rivers, Spain intends to raise the share of renewable-generated electricity to 81 percent of the total by 2030 as part of efforts to reduce its greenhouse gas emissions.

The regional government has defended the renewables projects, saying less than one percent of the land they use in the region had to be expropriated from reluctant landowners.

Spanish solar industry group UNEF, which represents more than 800 companies, says the projects boost tax revenues in rural communities.

They generate “significant amounts” that can be used to improve public services, said UNEF head Jose Donoso.

Solar park opponents in Lopera disagree and vow to continue their fight.

“Until the end. Nobody is going to take what is ours away from us,” said Juan Cantera, a 28-year-old farmer.

“Olive oil is everything in Lopera”.

rs/ds/imm/gv/tym

RED ELECTRICA CORPORACION

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Solar Energy

Lighter flexible tandem solar cells set new benchmark in efficiency

Published

3 days ago

April 15, 2025

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Lighter flexible tandem solar cells set new benchmark in efficiency

by Riko Seibo

Tokyo, Japan (SPX) Apr 15, 2025

The Korea Institute of Energy Research (KIER) has achieved a major milestone in solar technology by developing ultra-light and bendable tandem solar cells composed of perovskite and CIGS materials. These flexible solar cells have reached a record-breaking power conversion efficiency of 23.64 percent, the highest yet for their class.

Unlike traditional crystalline silicon-based cells, which are widely used due to cost efficiency and scalability, the new tandem design leverages thin-film technologies for enhanced adaptability. Silicon-perovskite tandems have reached up to 34.6 percent efficiency, but their weight and fragility restrict usage in weight-sensitive sectors such as aerospace and automotive. To address these challenges, KIER researchers turned to combining perovskite with copper indium gallium selenide (CIGS), a semiconductor known for its flexibility and suitability for curved surfaces.

CIGS thin-film solar cells can be fabricated on substrates like polyimide and metal foils, making them ideal for integration into non-flat surfaces. However, these cells have historically faced obstacles in efficiency and ease of production. KIER’s innovation lies in both its materials engineering and a novel lift-off fabrication technique.

The team introduced a process in which a glass base is first coated with a polyimide layer. The tandem solar cell is then constructed atop this foundation and subsequently detached from the glass, producing a freestanding, flexible device. This method offers stability during fabrication and improves layer uniformity, which enhances performance and consistency.

Another breakthrough came from managing alkali metal diffusion. During fabrication, potassium atoms from the glass substrate can penetrate the CIGS layer, creating defects that impair charge mobility. Using computational modeling, KIER scientists showed that the polyimide coating effectively suppresses this unwanted diffusion, resulting in fewer structural flaws and better performance.

The culmination of these innovations was a solar cell that not only surpassed the previous efficiency benchmark of 18.1 percent for flexible perovskite/CIGS tandems but also maintained 97.7 percent of its output after 100,000 flexing cycles, confirming its mechanical resilience.

“This research is a key achievement that demonstrates the commercial potential of next-generation high-efficiency solar cell technology with flexibility and lightness,” said Dr. Inyoung Jeong. “It serves as an important milestone toward realizing ultralight, flexible solar cells with 30 percent efficiency in the future.”

Dr. Kihwan Kim, principal investigator of the project, added, “The power-to-weight ratio of the fabricated solar cell is approximately 10 times higher than that of perovskite/silicon tandem solar cells, making it highly promising for applications in fields that require ultralight solar modules, such as building exteriors, vehicles, and aerospace.”

The study, published in the March issue of Joule (Impact Factor: 38.6), was conducted with support from KIER’s R and D Program and in collaboration with Professor Tae Kyung Lee of Gyeongsang National University and Professor Hae-Jin Kim of Yonsei University.

Research Report:Flexible and lightweight perovskite/Cu(In,Ga)Se2 tandem solar cells