Precision interface chemistry pushes perovskite solar cells beyond 26% efficiency

Helmholtz-Zentrum Berlin für Materialien und Energie

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A look inside the setup: Up to 5 × 5 samples can be measured automatically on the sample plate.

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Credit: Thomas Gries / HZB

An international research collaboration has developed a new molecular strategy for controlling one of the most critical interfaces in perovskite solar cells. The resulting solar cells reached a power conversion efficiency of 26.19% in the n i p architecture, together with strong operational stability under prolonged illumination and elevated temperature. The results have been published in the Journal of the American Chemical Society.

 

The work addresses a persistent challenge in perovskite photovoltaics: residual lead iodide, PbI₂, that remains at the surface of the perovskite after film formation. Although moderate amounts of PbI₂ can be beneficial during crystallization, an inhomogeneous distribution at the final interface can create local variations in surface potential, promote charge trapping, and increase nonradiative recombination. Now, an international collaboration, involving my own team, the Robotized Optoelectronic Material and Photovoltaic Engineering Group at Helmholtz Zentrum Berlin, and the research team of Professor Letian Dou at Purdue University and Emory University, has developed a new approach to tackle this problem.

We designed a new class of bidentate molecular ligands that interact selectively with residual PbI₂ through two anchoring sites. In contrast to conventional molecules that bind through a single interaction point, the new molecules reconstruct the residual PbI₂ into more stable and electronically favorable PbI₆ coordination structures while preserving the underlying three dimensional perovskite absorber. The most successful molecule, MeXT, produced a significantly more homogeneous electronic landscape across the perovskite surface. This reduced interfacial disorder and nonradiative voltage losses while improving the transport of photogenerated charge carriers toward the hole transport layer. The champion device reached 26.19% efficiency, with an open circuit voltage of 1.198 V, a fill factor of 83.2%, and a short circuit current density of 26.28 mA cm⁻². The device also delivered a stabilized efficiency of 25.65%. Under combined light and thermal stress at 75 °C, the treated devices retained more than 80% of their initial efficiency after 1000 hours.

Insights into charge transport

A central contribution from my team at HZB was the application of advanced transient and spatially resolved surface photovoltage measurements. These measurements provided direct insight into how the molecular treatment changes charge separation and extraction at the interface The optimised treatment did not simply passivate defects. It changed the interfacial charge selectivity itself. While insufficiently treated surfaces showed signatures of electron accumulation and trapping, the optimized bidentate treatment suppressed these electron trapping pathways and strongly promoted hole accumulation and extraction toward the hole transport layer. Measurements on complete perovskite, ligand, and hole transport layer stacks showed a faster and substantially stronger positive photovoltage response for the best treatment, consistent with enhanced hole extraction and reduced interfacial recombination.

Surface photovoltage allowed us to see what conventional efficiency measurements alone cannot reveal.We could directly distinguish how different molecular treatments change charge selectivity, defect activity, and extraction dynamics. This helped identify not only whether a treatment works, but why it works and where the optimum lies for the complete device.

The study demonstrates the strength of combining rational molecular design, advanced spectroscopy, spatial mapping, theoretical modelling, and complete device engineering. The chemical design and photovoltaic development were carried out in close collaboration with the group of Professor Letian Dou, with additional theoretical contributions from the team of Professor Brett M. Savoie. Together, we established a broader design principle for creating electronically homogeneous interfaces through selective chemical coordination rather than nonspecific surface treatment.

This work also points toward the next stage of photovoltaic research at HZB: autonomous materials and device optimisation. Over the coming three months, I will install a new fully robotized line for solar cell preparation, characterization, and optimisation will be installed at HySPRINT. The platform will combine automated device fabrication with rapid optoelectronic characterization and data driven optimisation. The goal is to accelerate experimental optimisation by approximately a factor of ten while generating deeper physical insight into the relationships between processing, interface properties, and final device performance.

The next step is to connect this type of fundamental interface understanding directly with autonomous experimentation. Instead of testing materials through long sequential optimisation campaigns, we want robotic systems to prepare devices, measure the relevant physical parameters, and use the results to decide which experiment should be performed next. With my team at HZB, we arepreparing to share the first photographs and videos from the new robotic laboratory in September and October 2026, marking the beginning of a new phase in automated discovery and optimisation of photovoltaic materials and interfaces.

 

Text by Dr. Artem Musiienko

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Journal

Journal of the American Chemical Society

DOI

10.1021/jacs.6c05316 

Method of Research

Experimental study

Subject of Research

Not applicable

Article Title

Selective Bidentate Coordination Reconstructs Residual PbI₂ to Homogenize Interfacial Energetics in Perovskite Solar Cells

Article Publication Date

8-Jul-2026

USF study identifies the hidden feeding grounds that fuel one of the ocean's most iconic sportfish

South Florida emerged as the only region consistently used by tarpon from multiple migratory groups, underscoring its importance to the species

University of South Florida

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A new USF study sheds light on feeding patters of iconic tarpon sportfish.

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Credit: David Mangum

TAMPA, Fla. (July 15, 2026) – Atlantic tarpon are famous for their long-distance migrations, traveling hundreds or even thousands of miles along the Gulf and Atlantic coasts. But where they feed along those journeys has remained largely unknown until now.

In a new study, a team of researchers led by University of South Florida integrative biologist Lucas Griffin combined five years of electronic tracking data and chemical signatures preserved in fish tissues to identify the key feeding areas that sustain tarpon during their annual migrations.

The study, published in Movement Ecology, found that tarpon do not feed randomly across their range. Instead, they rely on distinct "foraging landscapes" that act as fueling stations during migration.

The researchers identified three especially important feeding regions:

• South Florida
• The northern Gulf of Mexico
• The Mid-Atlantic coast

South Florida emerged as the only region consistently used by tarpon from multiple migratory groups, underscoring its importance to the species.

“These fish connect coastlines that look completely separate on a map – from the mangroves of the Florida Keys to the marshes of Louisiana and the Carolinas,” Griffin said. “The tarpon someone catches in the Keys might have spent the previous summer feeding in the northern Gulf. So fisheries across the Southeast depend on habitats hundreds of miles away – damage one place, and anglers feel it up and down the coast.”

The team analyzed tissue samples from 417 tarpon and linked those data with 85 acoustically tagged fish, whose movements, behaviors and migration patterns were tracked using sound waves. By combining the two datasets, they could estimate not only where fish traveled, but also where they had most likely been feeding.

The findings revealed that tarpon often obtain much of their food hundreds of kilometers from where they were captured and sampled, with the most probable foraging areas averaging about 300 kilometers (185 miles) away. Shorter-term blood samples reflected more recent, localized feeding, while longer-term fin-clip tissues captured broader feeding patterns over several months.

The findings also have important conservation implications. Because tarpon depend on a limited number of productive feeding areas, threats from coastal development, altered freshwater flows, habitat loss or climate don’t just harm one region — they could weaken the fishery across the entire range.

Beyond tarpon, the researchers say their approach offers a new framework for studying other migratory marine species whose feeding habitats have been difficult to identify. By pinpointing the places that provide the energy needed for migration, scientists and resource managers can better protect the ecosystems that support healthy fish populations and sustainable recreational fisheries.

“The next step is sorting out exactly what tarpon are eating in each of these hotspots,” Griffin said. “Once we know what type of prey they depend on across the regions – menhaden, mullet, anchovies, crabs – we can make sure these populations are managed with predators like tarpon in mind, not just as isolated fisheries.”

Co-authors of the study include Oliver N. Shipley (Stony Brook University), Aaron J. Adams (Bonefish & Tarpon Trust), Jacob W. Brownscombe (Great Lakes Laboratory for Fisheries and Aquatic Sciences), Simona A. Ceriani (Florida Fish and Wildlife Conservation Commission), Steven J. Cooke (Carleton University), Joseph J. Dello Russo (University of Maine), Seth D. Newsome (University of New Mexico), Michael Power (University of Waterloo), JoEllen K. Wilson (Bonefish & Tarpon Trust) and Andy Danylchuk (University of Massachusetts Amherst).

About the University of South Florida

The University of South Florida is a top-ranked research university serving approximately 50,000 students from across the globe at campuses in Tampa, St. Petersburg and USF Health. In 2025, U.S. News & World Report recognized USF with its highest overall ranking in university history, as a top 50 public university for the seventh consecutive year and as one of the top 15 best values among all public universities in the nation. U.S. News also ranks the USF Health Morsani College of Medicine in the highest tier, placing it as one of the top 16 medical schools in the nation and inside the top 10 among public universities. USF is a member of the Association of American Universities (AAU), a group that includes only the top 3% of universities in the U.S. With an all-time high of $750 million in research funding in 2025 and as a top 20 public university for producing U.S. patents, USF uses innovation to transform lives and shape a better future. The university generates an annual economic impact of nearly $10 billion for the state of Florida. USF’s Division I athletics teams compete in the American Conference. Learn more at www.usf.edu.

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Journal

Movement Ecology

DOI

10.1186/s40462-026-00677-3 

Method of Research

Observational study

Subject of Research

Animals

Article Title

Discrete foraging landscapes support large scale migrations of a marine fish

 

A new USF study sheds light on feeding patters of iconic tarpon sportfish.

 

A new USF study sheds light on feeding patters of iconic tarpon sportfish.

Credit

David Mangum

 

That avocado oil chip you're eating may not be made with pure avocado oil

Study finds 89% of avocado oil-labeled processed foods tested contain other oils

University of California - Davis

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These chips were among the 54 avocado-labeled products tested for avocado oil authenticity in the Wang lab at UC Davis. 

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Credit: Natalie Lopez-Alvarez / UC Davis

If you've been reaching for chips, mayonnaise or salad dressing labeled “made with avocado oil,” there's a good chance the oil inside isn't pure avocado oil, despite it being the only listed oil ingredient. University of California, Davis, researchers tested processed foods marketed as containing avocado oil. They found 48 of the 54 avocado oil-labeled products were adulterated with cheaper oils. The study was published in Applied Food Research.

Researchers purchased the products in 2025 and 2026 from online retailers and California stores. They represent only a portion of the avocado oil processed food market.

“Consumers are increasingly paying a premium for products made with avocado oil or olive oil,” said lead author Selina Wang, Professor of Cooperative Extension in the UC Davis Department of Food Science and Technology. "They deserve to get what they pay for and food manufacturers deserve confidence that the ingredients they purchase from suppliers are authentic."

Researchers found that of the products tested, 93% of chips, 71% of mayonnaises and 100% of salad dressings labeled as authentic avocado oil contained other oils. By contrast, when researchers applied the same purity tests to 20 olive oil-labeled processed foods, only one failed.

The gap between avocado and olive oil results reflects the fact that olive oil authenticity has been studied, tested and scrutinized for decades. Avocado oil is a relatively new and expensive product category and has not been monitored at the same level. As a result, consumers have less protection against misleading labels.

This is the latest in a series of UC Davis findings on the authenticity of avocado oil. A 2020 study found 82% of commercial bottled avocado oil were either rancid or mixed with other oils. A later study found 70% of private label oils were rancid or adulterated.

Testing processed foods

Researchers measure fatty acids and sterols — chemical “fingerprints” unique to each oil — to verify authenticity.  One potential concern is that processing, such as deep frying, blending or emulsifying, can change those chemical fingerprints. Wang’s team tested that directly and found fatty acids and sterols changed minimally. The study also used conservative criteria when evaluating authenticity.

“In our experience we’ve noticed natural variables, such as geographic origin and avocado variety, can change these fingerprints,” said Wang. “So we gave the samples some wiggle room, giving them a 10% margin of deviation to account for that, but 89% of the avocado products still failed.”

Where the blame lies

Wang said brands whose products failed may not know they are using adulterated oil. Many food companies source their oils from third-party brokers or from several different suppliers. Without rigorous testing, food companies may never detect adulterated oil. Wang said the adulteration likely originates with oil suppliers.

“If consumers are buying potato chips that say they’re made with 100% avocado oil, that should be the product that they're getting,” noted Wang. “I don't think there is enough accountability throughout the supply chain. Suppliers of adulterated oil may be hiding behind a couple of layers of supply chain, making it difficult to identify where the problem originated.”

Wang said at the same time, food companies could do more to monitor and verify the authenticity of the oil they purchase.

Consumers face the same outcome either way: They pay premium prices for products that aren’t what they claim to be. Avocado oil products in the study were priced comparably to olive oil products or higher — yet olive oil products were overwhelmingly pure while avocado oil products were overwhelmingly not.

Why it matters now

Grocery stores now stock far more avocado oil products than they did just a few years ago. Chips, mayonnaise and salad dressings "made with avocado oil" now occupy prime real estate in major grocery chains, marketed in many cases to consumers who are intentionally trying to avoid other oils. Wang's data suggests most of those consumers are not getting what they pay for.

Other authors of the study include Natalie Lopez-Alvarez, Xueqi Li and Benjamin Vizgordiski. The study received no outside funding.

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Journal

Applied Food Research

DOI

10.1016/j.afres.2026.102389 

Subject of Research

Not applicable

Article Title

Authenticity of avocado and olive oils used as ingredients in commercially processed foods

Article Publication Date

11-Jul-2026

 

Beyond the lab: rapid mass spectrometry techniques charted for traditional Chinese medicine analysis

A comprehensive review in Biomedical Analysis assesses the current state and future of direct mass spectrometry for the quality control, safety, and authentication of herbal medicines, highlighting key successes and remaining challenges

Biomedical Analysis

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Comprehensive overview of the direct mass spectrometry framework for TCM analysis, including platforms, applications, supportive data-analysis strategies, and future development trends.

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Credit: Kaiwen Zhang, Bin Li & Chang-jiang-sheng Lai

Traditional Chinese Medicine (TCM) products contain highly complex mixtures of chemical components, making rapid and reliable quality assessment a major analytical challenge. A new review published in the journal Biomedical Analysis provides a comprehensive assessment of how direct mass spectrometry is being applied to address this challenge. Researchers from institutions including Tianjin University of Commerce have synthesized more than a decade of scientific literature to evaluate the technology’s current capabilities and future potential. The review examines how these rapid analytical techniques, which require little to no sample preparation, can provide immediate chemical insights into herbal products, from raw materials to finished decoctions.

A New Lens for Ancient Medicine

Analyzing TCM is notoriously difficult due to the immense chemical diversity and complexity of herbal materials, which change significantly during processing. The review summarizes how direct mass spectrometry techniques, such as ambient ionization, bypass time-consuming separation steps common in conventional analysis. This approach allows for the rapid generation of a chemical fingerprinting profile, the monitoring of chemical changes as they happen, and even the visualization of where specific compounds are located within plant tissues. This provides a more direct and context-rich picture of a sample's chemical makeup.

Watching Chemistry Happen in Real Time

The authors identify process monitoring and safety evaluation as particularly mature applications. The review consolidates findings from studies where researchers used direct mass spectrometry to track the transformation of compounds during the decoction (boiling) of herbs. A key example highlighted is the real-time monitoring of toxic alkaloids in Aconitum species. By observing how concentrations of these compounds decrease over time, the technology offers a dynamic way to ensure the safety and proper processing of potent herbal medicines, moving beyond simple before-and-after snapshots.

Bridging the Gap from Signal to Significance

Despite its speed and convenience, the review points out significant hurdles that prevent the technology's widespread adoption for all analytical tasks. The authors conclude from the literature that major bottlenecks remain in absolute quantification, where determining the exact amount of a substance is critical. Issues like matrix effects—interference from the complex background of the sample—and a lack of consistency between different laboratories currently limit its use for regulatory decision-making. The review also notes that the technology's performance is uneven across different chemical classes; it is highly effective for alkaloids but remains challenging for compounds like carbohydrates and polysaccharides.

The synthesis of existing research shows that the most developed and practical applications are in rapid fingerprinting for authentication and origin discrimination. These methods are already capable of quickly distinguishing between similar-looking herbs, identifying adulterants, and verifying the geographical source of a sample. This capability is approaching readiness for routine quality control in the herbal medicine industry, where speed and high throughput are essential.

Looking forward, the authors outline a path for advancing the field. Progress will depend less on developing new ionization techniques and more on standardizing existing methods to improve reliability and inter-laboratory comparability. The creation of dedicated, standardized spectral databases for TCM compounds is essential for more confident identification. The review also discusses the growing role of portable mass spectrometry for on-site testing and the use of artificial intelligence (AI) to help interpret the vast amounts of complex data produced by these methods.

Ultimately, the review presents a task-oriented roadmap for the application of direct mass spectrometry in TCM. It clarifies which analytical goals are already achievable—such as rapid screening and process monitoring—and which require further methodological refinement, including robust quantification and in-depth pharmacokinetic studies. The long-term goal is to evolve this powerful toolbox into a fully integrated evidence platform that connects rapid chemical analysis with the quality, safety, and efficacy of Traditional Chinese Medicine.

DOI: 10.1016/j.bioana.2026.05.001

Read the full article: https://doi.org/10.1016/j.bioana.2026.05.001

Call for Papers

Biomedical Analysis invites submissions for its 2026 Special Issue, “Biosensing and Nanoanalytical Technologies,” scheduled for publication in December 2026. The issue welcomes original research articles and reviews on innovative biosensing strategies, nanoanalytical technologies, functional nanomaterials, optical and electrochemical sensing, signal amplification, imaging, microfluidic and point-of-care platforms, and biomedical applications in disease diagnosis and precision medicine.

The submission deadline is September 30, 2026. Please refer to the Guide for Authors to prepare your manuscript and select the article type of ": “VSI: Biosensing and Nanoanalytical Technologies" when submitting your manuscript online. Submit your manuscript at: https://www2.cloud.editorialmanager.com/bioana/default2.aspx

About Biomedical Analysis

Biomedical Analysis is an international, peer-reviewed, open access journal published by Elsevier and KeAi and jointly sponsored by Sun Yat-sen University and the Guangzhou Analysis and Testing Center.

The journal publishes high-quality research in biomedical engineering, bioanalytical chemistry, biochemistry, genetics, biology, biomaterials, medicine, and related interdisciplinary fields, with a particular focus on biomedical testing, sensing technologies, and analytical innovation. Biomedical Analysis is indexed in Scopus, CAS, DOAJ, and EBSCO. Article processing charges (APCs) are currently waived for accepted manuscripts through the end of 2026.

Journal website: https://www.sciencedirect.com/journal/biomedical-analysis.

  

General workflow of direct mass spectrometry and comparison with LC-MS/GC-MS.

Credit

Kaiwen Zhang, Bin Li & Chang-jiang-sheng Lai

DOI

10.1016/j.bioana.2026.05.001 

Method of Research

Literature review

Subject of Research

Not applicable

Article Title

Direct mass spectrometry for traditional Chinese medicine analysis: Analytical strategies, applications, and future perspectives