It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Saturday, July 18, 2026
Brexit nurse exodus linked to more than 3,700 extra hospital deaths, researchers warn
The sharp fall in EU nurses joining the NHS after the Brexit referendum may have contributed to more than 1,200 additional patient deaths each year in England, according to new research led by the University of Surrey in partnership with the University of Aberdeen, Harvard Business School and Vienna University of Economics and Business (WU).
The research suggests the biggest impact was felt by hospitals that had relied most heavily on recruiting nurses from the EU before the 2016 vote. While these hospitals largely replaced departing EU staff with nurses from outside Europe, patient care still worsened, with higher rates of emergency deaths and unplanned readmissions.
The study, published in The Economic Journal, the official journal of the Royal Economic Society, estimates that, across the first three years after the referendum, hospitals with greater dependence on EU nurses experienced 3,714 additional emergency patient deaths and almost 14,000 extra emergency readmissions to hospital after initial discharge. The researchers found no evidence that these patient health outcomes were caused by reduced hospital funding, fewer beds or an increase in patient numbers.
Researchers say the findings challenge the idea that simply filling vacancies is enough to protect healthcare quality. Instead, they argue that sudden restrictions on international recruitment can force employers to lower hiring standards when skilled workers become harder to attract.
To investigate the impact, researchers analysed more than 32 million emergency hospital admissions across 130 NHS hospitals between 2012 and 2019. They linked patient records with NHS workforce data to compare hospitals according to how reliant they had been on EU nurses before the referendum. They found that hospitals with the highest proportions of EU nurses before Brexit experienced the greatest decline in patient outcomes afterwards.
Giuseppe Moscelli, Professor of Economics at the University of Surrey and principal investigator of the study, said:
“Hospitals were able to recruit replacement nurses, but our findings suggest they had to recruit from a smaller and less experienced pool of applicants. That appears to have had real consequences for patients.”
The researchers found hospitals responded to the drop in EU applicants by recruiting more nurses from outside Europe. However, newly recruited nurses after the referendum were more likely to be appointed to lower NHS salary bands, suggesting they had less experience or fewer qualifications than those they replaced. The research also found nurses working in the most affected hospitals reported being less satisfied with the quality of care they were able to provide.
Professor Moscelli continued:
“Many countries, including the UK, depend on internationally trained healthcare professionals. Our findings show that immigration policy can have unintended consequences far beyond the labour market. Decisions that make a country less attractive to skilled workers can ultimately affect the quality of care received by patients.
“Policymakers should recognise that healthcare systems competing for skilled international workers need to consider not only the number of staff they recruit, but also how immigration policies influence who chooses to apply.”
Immigration, Workforce Composition, and Organisational Performance: The Effect of Brexit on NHS Hospital Quality
Article Publication Date
18-Jul-2026
When Black Sea waters reshaped Eastern Mediterranean circulation 11,000 years ago
A new study led by the University of Barcelona reveals that freshwater exported from the Black Sea to the Aegean Sea triggered major environmental changes across the Eastern Mediterranean
A new study led by the University of Barcelona reveals that freshwater exported from the Black Sea to the Aegean Sea triggered major environmental changes across the Eastern Mediterranean.
An international team of researchers led by the University of Barcelona, in collaboration with the University of the Aegean and the Hellenic Centre for Marine Research, has uncovered evidence showing that a massive outflow of low-salinity water from the Black Sea into the Aegean Sea during the Early Holocene (approximately 11,000-6,000 years ago) played a much more important role in shaping the Eastern Mediterranean than previously thought.
The study, published in the Nature Portfolio journal Communications Earth & Environment, demonstrates that freshwater exported from the Black Sea enhanced surface-water stratification in the Aegean Sea, suppressing the formation of deep waters and contributing to the development of the so-called Sapropel 1, a widespread organic-rich sediment layer deposited across the Eastern Mediterranean during the Early Holocene.
The findings extend beyond the Eastern Mediterranean’s past. By demonstrating how large freshwater inputs can disrupt deep-water formation and reorganize marine circulation, the study offers valuable insights into the links between climate, hydrology and ocean circulation during warm periods, helping scientists better understand the potential consequences of future climate change.
The Black Sea: More important than previously thought
For decades, scientists have largely attributed the formation of Sapropel 1 to increased freshwater input from North African rivers and enhanced precipitation over the northern Mediterranean region. These processes were thought to reduce deep-water formation and promote conditions favourable for the accumulation of organic-rich sediments on the seafloor. The new findings challenge this long-standing view by identifying the Black Sea as a major and previously underestimated driver of these environmental changes.
The results reveal that the combination of intensified meltwater input and increased precipitation across the vast Black Sea drainage basin during the Early Holocene strengthened the export of low-salinity water through the Dardanelles Strait. This freshwater pulse triggered a major reorganization of water masses in the northern and central Aegean Sea, increasing stratification of the water column and reducing the formation of deep waters.
“Our findings show that the formation of Sapropel 1 cannot be explained solely by changes in North African river discharge and regional precipitation,” explains Dimitris Evangelinos, lead author of the study and member of the Marine Geosciences Research Group (Gmar) at the UB’s Faculty of Earth Sciences.
“The Black Sea acted as a powerful source of freshwater that fundamentally altered ocean circulation in the Aegean Sea and played a decisive role in the environmental transformation of the Eastern Mediterranean”, explains Evangelinos, from the UB’s Department of Earth and Ocean Dynamics.
More than 42,000 years of environmental history
To reach these conclusions, the researchers analysed a marine sediment core recovered from the central Aegean Sea, close to key deep-water formation areas in the northern Aegean. The sediment archive preserves more than 42,000 years of environmental history. The study relied on a suite of advanced analyses carried out in state-of-the-art laboratories at the UB and its Science and Technology Centres (CCiTUB). By combining multiple innovative approaches, including grain-size analysis, X-ray fluorescence scanning, radiogenic isotopes and stable isotope geochemistry, the team reconstructed past changes in ocean circulation and distinguish the influence of Black Sea outflow from other climatic and hydrological processes.
This research was supported by the MORIA project (2023-2027), and received funding from the the State Research Agency of the Ministry of Science, Innovation and Universities, the European Research Council Consolidator Grant and the NextGenerationEU programme, among other institutions.
Marine sediment core scanned using an Avaatech X-ray fluorescence (XRF) core scanner at the CORELAB, Universitat de Barcelona (Spain) to obtain high-resolution geochemical records. The dark sedimentary unit visible in the upper part of the core corresponds to the organic-rich sapropel S1 layer, which is characterized by elevated organic matter content relative to the surrounding sediments.
Some of the study's authors aboard the Spanish research vessel (R/V)Odón de Buen. From left to right: Isabel Cacho, Leopoldo Pena, Sara Campderrós, Dimitris Evangelinos, and Jaime Frigola.
Dimitris Evangelinos, first author of the study and postdoctoral researcher at the Universitat de Barcelona, analyzing marine sediment samples used to reconstruct past Mediterranean ocean and climate changes.
Sara Campderrós, author of the study, sampling the marine sediment core for sedimentological, geochemical, and isotopic analyses
Early Holocene vigorous Black Sea outflow and the onset of sluggish Aegean deep-water convection
New contact material boosts the efficiency of perovskite solar cells
Caborane based material offers multiple advantages by replacing the standard fullerene electron transport material, the study shows. The novel material is now commercially available
Helmholtz-Zentrum Berlin für Materialien und Energie
A newly developed material for the electron contact improves the efficiency of single perovskite solar cells and perovskite/silicon tandem solar cells. The new material is based on a carborane molecule. It offers several advantages over the standard material C60, as shown by the study led by Steve Albrecht’s team. The new material has since been patented and is already commercially available.
Perovskite solar cells are not only exceptionally inexpensive to manufacture but also achieve very high efficiency levels. Single-junction perovskite devices already can convert over 27 per cent of sunlight into electrical energy, while perovskite-silicon tandem cells have even achieved efficiencies of over 35 per cent. Until now, a layer of so-called ‘football molecules’ (C60) has been used to transport electrons away. However, a significant proportion of the charge carriers are lost at the interface between the C60 layer and the perovskite absorber. Furthermore, C60 materials are relatively expensive and tend to delaminate over time, compromising the cell’s stability.
Novel material developed
In collaboration with a group from Kaunas University of Technology (KTU) in Lithuania and other partners, the team led by Professor Steve Albrecht at HZB has now developed a novel carborane-based material. Not only can it replace C60 electron-transport materials, it is also superior in many respects. The material can be produced from commercially available reagents. The molecules consist of a meta-carborane core with two 9-fluorenylidene malononitrile functional groups (mCB-FMN).
Multiple advantages
Compared to C60, the thin film can be deposited from the vapour phase at lower temperatures. This means that the production of the layer requires less energy and places less thermal stress on the equipment. The evaporated mCB-FMN forms a uniform layer on the perovskite absorber. Measurements of transient surface photovoltage (trSPV) and photoluminescence (PL) reveal that this layer facilitates the transport of electrons very effectively with fewer losses at the interface than with C60. Investigations using He-I ultraviolet photoemission spectroscopy (He-UPS) showed that the mCB-FMN layer and the perovskite absorber layer are well matched energetically. Density functional theory (DFT) calculations suggest that surface defects are passivated, which could be a further reason for the lower losses. Electron microscopy and in-situ ellipsometry during deposition of the overlying SnOx buffer layer demonstrate that the new ETM even improves film growth. Mechanical tests confirm that the new material also enhances interfacial adhesion and, consequently, stability within the perovskite/ETM/SnOx layer stack.
Improved efficiency
As a result, the efficiency of a single p-i-n perovskite cell increases by 1.5% (in absolute terms) when the new ETM replaces C60. In perovskite-silicon tandem cells, the efficiency increases by as much as 2.4% (in absolute terms) compared to the reference cell. This is because the lower parasitic absorption also allows more light to reach the photoactive layers.
‘We have developed a very high-performance substitute material for fullerenes in perovskite solar cells, and we have demonstrated its benefits through different measurements,’ says Lea Zimmermann, first author of the study.
Already commercially available
The new material has already attracted considerable interest in both academic and industrial circles, and it was selected for the “Best Scientific Content Award” at the 2025 TandemPV International Workshop. A European patent application has been filed (EP 25175871.0) has been filed, covering mCB-FMN, its derivatives and their use in solar cells. ‘Dyenamo has now brought this material to market with the aim of enabling its widespread use,’ explains Steve Albrecht.
Novel materials for tandem solar cells
His team had already achieved a breakthrough with self-assembling monolayers (SAMs) for the hole-conducting contact layers on the other side of the solar cell, in collaboration with international partners. They are now aiming to achieve the same for the electron transport layer: ‘We are currently working flat out on developing further novel materials in this class and we believe that this class of materials could also revolutionise tandem solar cells,’ says Albrecht.
Credit: Yan Jiang from Beijing Institute of Technology.
A group of researchers from Beijing Institute of Technology, National Institute of Clean-and-Low-Carbon Energy, Beijing Engineering Research Center of Nano-structured Thin Film Solar Cells and Beijing University of Chemical Technology, has developed a coordination-regulated strategy to stabilize wide-bandgap perovskites for efficient perovskite/CIGS tandem solar cells. By introducing bis(2-pyridylmethyl) sulfide (2PyS) to regulate the local Pb2+ coordination environment, the researchers suppressed defect formation, reduced halide ion migration, and mitigated photoinduced phase segregation. The optimized wide-bandgap perovskite solar cells achieved an efficiency of 22.21% and retained more than 91% of their initial performance after 2000 hours of continuous operation. When integrated with a CIGS bottom cell, the resulting four-terminal perovskite/CIGS tandem solar cell delivered an overall efficiency of 29.71%. This study provides a promising molecular design route toward stable and efficient tandem photovoltaics.
Wide-bandgap perovskites are essential light absorbers for tandem solar cells, where they can be paired with narrow-bandgap materials such as crystalline silicon or Cu(In,Ga)Se2 (CIGS) to overcome the efficiency limit of single-junction photovoltaics. Their tunable bandgaps and excellent optoelectronic properties make them attractive candidates for next-generation solar technologies. However, wide-bandgap perovskites commonly rely on mixed-halide compositions, which are vulnerable to halide ion migration under illumination and thermal stress. This migration can lead to the formation of iodine-rich and bromine-rich domains, causing spatial bandgap inhomogeneity, enhanced non-radiative recombination, and rapid performance degradation. Therefore, stabilizing wide-bandgap perovskites under real operating conditions remains a major challenge for high-performance tandem solar cells.
A key origin of this instability is the presence of undercoordinated Pb2+ defects and associated halide vacancies. These defects not only act as recombination centers but also disturb the local lattice environment and provide pathways for halide ion migration. Conventional post-treatment passivation strategies can reduce some defects after crystallization, but they often offer limited control over defect formation during the film growth process. As a result, photoinduced halide segregation remains difficult to suppress during long-term device operation.
The Solution: The group researchers reported a coordination-regulated defect suppression strategy by introducing bis(2-pyridylmethyl) sulfide (2PyS) into wide-bandgap perovskite films. The 2PyS molecule strongly coordinates with Pb2+ ions and modulates the local coordination environment during film formation. This interaction reduces the density of undercoordinated Pb2+ defects and suppresses the formation of halide vacancies, so limiting defect-assisted ion migration and mitigating photoinduced halide segregation.
Theoretical calculations showed that 2PyS has stronger binding with PbI2 than commonly used organic solvents such as Dimethylformamide (DMF) and Dimethyl sulfoxide (DMSO), indicating its dominant role in regulating Pb2+ coordination during crystallization. Moreover, in situ photoluminescence measurements further revealed that 2PyS modulates crystallization kinetics, suppresses rapid nucleation, and promotes more homogeneous film growth. As a result, the modified perovskite films exhibit improved optoelectronic properties, reduced non-radiative recombination, enhanced structural integrity, and stronger phase stability under coupled illumination and thermal stress.
The optimized wide-bandgap perovskite solar cells achieved a power conversion efficiency of 22.21% with an open-circuit voltage of 1.20 V. The devices also exhibited significantly improved operational stability, retaining more than 91% of their initial efficiency after 2000 hours of continuous operation. Furthermore, the semi-transparent wide-bandgap perovskite top cell was integrated with a CIGS bottom cell to construct a four-terminal tandem solar cell, achieving an overall efficiency of 29.71%. These results demonstrate the great potential of coordination chemistry for stabilizing wide-bandgap perovskites and enabling efficient tandem photovoltaic devices.
The Future: Future research will focus on designing more coordination-active molecules with tailored binding configurations, appropriate steric structures, and multifunctional passivation capabilities. Such molecular engineering may enable more precise control over crystallization kinetics, defect formation, and ion migration in wide-bandgap perovskites. Advanced operando characterization techniques will also be important for revealing the dynamic evolution of defects, halide redistribution, and phase segregation under realistic operating conditions. Extending this coordination-regulated strategy to higher-bandgap perovskites, all-perovskite tandems, perovskite/silicon tandems, and large-area perovskite/CIGS modules represents a promising direction toward commercialization.
The Impact: This work highlights the critical role of coordination chemistry in controlling defect formation and phase stability in wide-bandgap perovskites. By targeting defect formation at its origin, the strategy provides an effective pathway to suppress halide ion migration and photoinduced phase segregation, two long-standing obstacles in wide-bandgap perovskite photovoltaics. The demonstrated 29.71% four-terminal perovskite/CIGS tandem solar cell shows the practical potential of this approach for high-efficiency, stable tandem solar energy conversion.
The research has been recently published in the online edition of Materials Futures, an international journal in the field of interdisciplinary materials science research.
Reference: Chenxi Wu, Shuping Lin, Zhongyang Zhang, Yao Sun, Teng Cheng, Quanhong Han, Mengqi Guo, Jiahong Tang, Minghua Li, Dongxu Lin, Dalong Zhong, Ying Zhao, Yan Jiang. Coordination-regulated defect suppression enables stable wide-bandgap perovskites for efficient perovskite/CIGS tandem solar cells[J]. Materials Futures, 2026, 5(3): 035106. DOI: 10.1088/2752-5724/ae7817
Credit: Yan Jiang from Beijing Institute of Technology.
A group of researchers from Beijing Institute of Technology, National Institute of Clean-and-Low-Carbon Energy, Beijing Engineering Research Center of Nano-structured Thin Film Solar Cells and Beijing University of Chemical Technology, has developed a coordination-regulated strategy to stabilize wide-bandgap perovskites for efficient perovskite/CIGS tandem solar cells. By introducing bis(2-pyridylmethyl) sulfide (2PyS) to regulate the local Pb2+ coordination environment, the researchers suppressed defect formation, reduced halide ion migration, and mitigated photoinduced phase segregation. The optimized wide-bandgap perovskite solar cells achieved an efficiency of 22.21% and retained more than 91% of their initial performance after 2000 hours of continuous operation. When integrated with a CIGS bottom cell, the resulting four-terminal perovskite/CIGS tandem solar cell delivered an overall efficiency of 29.71%. This study provides a promising molecular design route toward stable and efficient tandem photovoltaics.
Wide-bandgap perovskites are essential light absorbers for tandem solar cells, where they can be paired with narrow-bandgap materials such as crystalline silicon or Cu(In,Ga)Se2 (CIGS) to overcome the efficiency limit of single-junction photovoltaics. Their tunable bandgaps and excellent optoelectronic properties make them attractive candidates for next-generation solar technologies. However, wide-bandgap perovskites commonly rely on mixed-halide compositions, which are vulnerable to halide ion migration under illumination and thermal stress. This migration can lead to the formation of iodine-rich and bromine-rich domains, causing spatial bandgap inhomogeneity, enhanced non-radiative recombination, and rapid performance degradation. Therefore, stabilizing wide-bandgap perovskites under real operating conditions remains a major challenge for high-performance tandem solar cells.
A key origin of this instability is the presence of undercoordinated Pb2+ defects and associated halide vacancies. These defects not only act as recombination centers but also disturb the local lattice environment and provide pathways for halide ion migration. Conventional post-treatment passivation strategies can reduce some defects after crystallization, but they often offer limited control over defect formation during the film growth process. As a result, photoinduced halide segregation remains difficult to suppress during long-term device operation.
The Solution: The group researchers reported a coordination-regulated defect suppression strategy by introducing bis(2-pyridylmethyl) sulfide (2PyS) into wide-bandgap perovskite films. The 2PyS molecule strongly coordinates with Pb2+ ions and modulates the local coordination environment during film formation. This interaction reduces the density of undercoordinated Pb2+ defects and suppresses the formation of halide vacancies, so limiting defect-assisted ion migration and mitigating photoinduced halide segregation.
Theoretical calculations showed that 2PyS has stronger binding with PbI2 than commonly used organic solvents such as Dimethylformamide (DMF) and Dimethyl sulfoxide (DMSO), indicating its dominant role in regulating Pb2+ coordination during crystallization. Moreover, in situ photoluminescence measurements further revealed that 2PyS modulates crystallization kinetics, suppresses rapid nucleation, and promotes more homogeneous film growth. As a result, the modified perovskite films exhibit improved optoelectronic properties, reduced non-radiative recombination, enhanced structural integrity, and stronger phase stability under coupled illumination and thermal stress.
The optimized wide-bandgap perovskite solar cells achieved a power conversion efficiency of 22.21% with an open-circuit voltage of 1.20 V. The devices also exhibited significantly improved operational stability, retaining more than 91% of their initial efficiency after 2000 hours of continuous operation. Furthermore, the semi-transparent wide-bandgap perovskite top cell was integrated with a CIGS bottom cell to construct a four-terminal tandem solar cell, achieving an overall efficiency of 29.71%. These results demonstrate the great potential of coordination chemistry for stabilizing wide-bandgap perovskites and enabling efficient tandem photovoltaic devices.
The Future: Future research will focus on designing more coordination-active molecules with tailored binding configurations, appropriate steric structures, and multifunctional passivation capabilities. Such molecular engineering may enable more precise control over crystallization kinetics, defect formation, and ion migration in wide-bandgap perovskites. Advanced operando characterization techniques will also be important for revealing the dynamic evolution of defects, halide redistribution, and phase segregation under realistic operating conditions. Extending this coordination-regulated strategy to higher-bandgap perovskites, all-perovskite tandems, perovskite/silicon tandems, and large-area perovskite/CIGS modules represents a promising direction toward commercialization.
The Impact: This work highlights the critical role of coordination chemistry in controlling defect formation and phase stability in wide-bandgap perovskites. By targeting defect formation at its origin, the strategy provides an effective pathway to suppress halide ion migration and photoinduced phase segregation, two long-standing obstacles in wide-bandgap perovskite photovoltaics. The demonstrated 29.71% four-terminal perovskite/CIGS tandem solar cell shows the practical potential of this approach for high-efficiency, stable tandem solar energy conversion.
The research has been recently published in the online edition of Materials Futures, an international journal in the field of interdisciplinary materials science research.
Reference: Chenxi Wu, Shuping Lin, Zhongyang Zhang, Yao Sun, Teng Cheng, Quanhong Han, Mengqi Guo, Jiahong Tang, Minghua Li, Dongxu Lin, Dalong Zhong, Ying Zhao, Yan Jiang. Coordination-regulated defect suppression enables stable wide-bandgap perovskites for efficient perovskite/CIGS tandem solar cells[J]. Materials Futures, 2026, 5(3): 035106. DOI: 10.1088/2752-5724/ae7817
Journal
Materials Futures
DOI
10.1088/2752-5724/ae7817
Article Title
Coordination-regulated defect suppression enables stable wide-bandgap perovskites for efficient perovskite/CIGS tandem solar cells
