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We establish one-body reduced density-matrix functional theory for the canonical ensemble in a finite basis set at an elevated temperature. Including temperature guarantees differentiability of the universal functional by occupying all states and additionally not fully occupying the states in a fermionic system. We use convexity of the universal functional and invertibility of the potential-to-1RDM map to show that the subgradient contains only one element which is equivalent to differentiability. This allows us to show that all 1RDMs with a purely fractional occupation number spectrum ($0 < n_i < 1 \; \forall_i$) are uniquely $v$-representable up to a constant., 7 pages, 1 figure

Funding: LKJ acknowledges funding from UKRI-FLF through MR/T022094/1. LKJ also acknowledges, Professor Iain Baikie for assistance with the work function and APS measurements, and Professor Phil King and Gordon Kentish, School of Physics and Astronomy, University of St Andrews for the XRD measurements and would like to acknowledge (EPSRC): EP/T023449/1. This research used resources of the Advanced Light Source, a U.S. DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. Work was performed at beamline 12.3.2, beamline scientist Nobumichi Tamura. M. A. acknowledges support by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division under Contract No. DE-AC02-05-CH11231 (D2S2 program KCD2S2). Work at the Molecular Foundry was supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. IDWS acknowledges funding from EPSRC through EP/l017008/1. Indoor photovoltaics are receiving tremendous attention due to the continuous development of the Internet of Things. The present study reports how the fast processing of the triple halide perovskite enables the retention of chlorine and the beneficial role of chlorine in enhancing the indoor light harvesting of a wide bandgap triple anion (TA) perovskite CH3NH3PbI2.6Br0.2Cl0.2. The kinetics of chlorine incorporation/escape investigated by in situ grazing incidence wide-angle X-ray scattering revealed the escape of chlorine after the first ten minutes of thermal annealing and the findings were corroborated with elemental analysis by wavelength dispersive X-ray spectroscopy. The best-performing TA perovskite indoor-photovoltaic device achieved a steady-state power conversion efficiency (PCE) of 25.1% with an output power density of ∼75 μW cm−2 under 1000 lux indoor illumination (0.3 mW cm−2 irradiance). Improved crystalline quality, reduced density of trap states and longer carrier lifetime were achieved by the triple anion alloying method. The detrimental role of the commonly used hole transporting layer (HTL) of Spiro-MeOTAD under indoor lighting conditions leading to J–V hysteresis was also investigated, which could then be effectively suppressed by replacing Spiro-MeOTAD with undoped P3HT. The optimized TA perovskite indoor PV cells were then successfully used to wirelessly power a textile fiber-based temperature sensor. The results from the present study demonstrate a novel route to incorporate chlorine effectively and maximize the steady state power output from halide perovskite indoor photovoltaic devices and their promising potential for the IoT industry. Publisher PDF

Text-mining inspired study on halide double perovskite formation using in situ structural and optical probes.

Non-fullerene acceptors based organic solar cells represent the frontier of the field, owing to both the materials and morphology manipulation innovations. Non-radiative recombination loss suppression and performance boosting are in the center of organic solar cell research. Here, we developed a non-monotonic intermediate state manipulation strategy for state-of-the-art organic solar cells by employing 1,3,5-trichlorobenzene as crystallization regulator, which optimizes the film crystallization process, regulates the self-organization of bulk-heterojunction in a non-monotonic manner, i.e., first enhancing and then relaxing the molecular aggregation. As a result, the excessive aggregation of non-fullerene acceptors is avoided and we have achieved efficient organic solar cells with reduced non-radiative recombination loss. In PM6:BTP-eC9 organic solar cell, our strategy successfully offers a record binary organic solar cell efficiency of 19.31% (18.93% certified) with very low non-radiative recombination loss of 0.190 eV. And lower non-radiative recombination loss of 0.168 eV is further achieved in PM1:BTP-eC9 organic solar cell (19.10% efficiency), giving great promise to future organic solar cell research.

Complex phenomena are prevalent during the formation of materials, which affect their processing-structure-function relationships. Thin films of methylammonium lead iodide (CH3NH3PbI3, MAPI) are processed by spin coating, antisolvent drop, and annealing of colloidal precursors. The structure and properties of transient and stable phases formed during the process are reported, and the mechanistic insights of the underlying transitions are revealed by combining in situ data from grazing-incidence wide-angle X-ray scattering and photoluminescence spectroscopy. Here, we report the detailed insights on the embryonic stages of organic-inorganic perovskite formation. The physicochemical evolution during the conversion proceeds in four steps: i) An instant nucleation of polydisperse MAPI nanocrystals on antisolvent drop, ii) the instantaneous partial conversion of metastable nanocrystals into orthorhombic solvent-complex by cluster coalescence, iii) the thermal decomposition (dissolution) of the stable solvent-complex into plumboiodide fragments upon evaporation of solvent from the complex and iv) the formation (recrystallization) of cubic MAPI crystals in thin film., Complex phenomena are prevalent during the formation of materials, and they affect the processing structure-function relationship. Here the authors elucidate the stochastic transformation processes happening during the spin coating of perovskite colloidal precursors by multimodal characterization.

Background Preterm neonates frequently experience hypernatremia (plasma sodium concentrations >145 mmol/l), which is associated with clinical complications, such as intraventricular hemorrhage. Study design In this single center retrospective observational study, the following 7 risk factors for hypernatremia were analyzed in very low gestational age (VLGA, below 32 weeks) neonates: gestational age (GA), delivery mode (DM; vaginal or caesarian section), sex, birth weight, small for GA, multiple birth, and antenatal corticosteroids. Machine learning (ML) approaches were applied to obtain probabilities for hypernatremia. Results 824 VLGA neonates were included (median GA 29.4 weeks, median birth weight 1170 g, caesarean section 83%). 38% of neonates experienced hypernatremia. Maximal sodium concentration of 144 mmol/l (interquartile range 142–147) was observed 52 hours (41–65) after birth. ML identified vaginal delivery and GA as key risk factors for hypernatremia. The risk of hypernatremia increased with lower GA from 22% for GA ≥ 31–32 weeks to 46% for GA Conclusion VLGA neonates with vaginal delivery and low GA have the highest risk for hypernatremia. Early identification of neonates at risk and early intervention may prevent extreme sodium excursions and associated clinical complications. Hintergrund Bei Fruhgeborenen tritt haufig eine Hypernatriamie (Natrium im Plasma > 145 mmol/l) auf, welche mit klinischen Komplikationen wie Hirnblutungen assoziiert ist. Patienten und MethodenDiese retrospektive Beobachtungsstudie untersuchte folgenden 7 Risikofaktoren fur Hypernatriamie bei Neugeborenen mit sehr niedrigem Gestationsalter (VLGA, unter 32 Wochen): Gestationsalter (GA), Entbindungsmodus (DM) (vaginal oder Kaiserschnitt), Geschlecht, Geburtsgewicht, klein fur GA, Mehrlingsgeburt und pranatale Lungenreife. Durch maschinelles Lernen (ML) wurden Risikofaktoren fur Hypernatriamie analysiert. Ergebnisse 824 VLGA-Neugeborene wurden eingeschlossen (GA Median 29,4 Wochen, Geburtsgewicht Median 1170 g, Kaiserschnitt 83%). 38% der Neugeborenen zeigten eine Hypernatriamie. Die maximale Natriumkonzentration von 144 mmol/l (Interquartilbereich 142–147) wurde 52 Stunden (41–65) nach der Geburt beobachtet. ML identifizierte vaginale Geburt und GA als Hauptrisikofaktoren fur Hypernatriamie. Die Haufigkeit stieg mit niedrigerem GA von 22% fur GA ≥31–32 Wochen auf 46% fur GA Schlussfolgerung VLGA-Neugeborene mit vaginaler Entbindung und niedrigem GA haben das hochste Risiko fur Hypernatriamie. Fruhes Identifizieren von Risikopatienten und fruhe Intervention konnten extreme Natriumexkursionen und damit verbundene klinische Komplikationen verhindern.

Summary Inspired by the fascinating class of hybrid organic-inorganic halide perovskite materials, halide double perovskites have emerged as non-toxic Pb-free contenders for application as active layers in optoelectronic devices. Heterovalent substitution of Pb2+ by non-toxic metal cations yields the double-perovskite structure, which allows for compositional flexibility. In fact, the compositional space is large, given that multiple cations and halides can be combined, resulting in >106 perovskite combinations. A starkly increasing number of stable halide double-perovskite compositions are theoretically predicted. The synthesis, however, lags behind, and many double perovskites are primarily synthesized as powder samples instead of thin films. The latter, however, are needed for thin-film devices such as solar cells, light-emitting devices, and thin-film transistors. Comparing the synthetic approaches successfully applied to hybrid perovskites to methods used for the fabrication of double perovskites, the latter are clearly in their very infancy. The question is whether solution engineering and compositional modification strategies can be exploited to match the exceptional optoelectronic properties of hybrid perovskites. This review is motivated by a text mining effort that illustrates not only the prevalence of powder over thin-film synthesis but also the discrepancy between the number of compositions experimentally realized and studied and the many predicted compositions. Here we summarize the synthesis aspects of halide double perovskites, and in particular of thin films, including deposition techniques and synthetic modifications to alter film properties.

Pbp1 (poly(A)-binding protein - binding protein 1) is a cytoplasmic stress granule marker that is capable of forming condensates that function in the negative regulation of TORC1 signaling under respiratory conditions. How mutations in its mammalian ortholog ataxin-2 are linked to neurodegenerative conditions remains unclear. Here, we show that loss of Pbp1 leads to decreases in amounts of mitochondrial proteins whose encoding mRNAs are targets of Puf3, a member of the PUF (Pumilio and FBF) family of RNA-binding proteins. We found that Pbp1 stabilizes and promotes the translation of Puf3-target mRNAs in respiratory conditions, such as those involved in the assembly of cytochrome c oxidase. We further show that Pbp1 and Puf3 interact through their respective low complexity domains, which is required for Puf3-target mRNA stabilization and translation. Our findings reveal a key role for Pbp1-containing assemblies in enabling the translation of mRNAs critical for mitochondrial biogenesis and respiration. They may further begin to explain prior associations of Pbp1/ataxin-2 with RNA, stress granule biology, mitochondrial function, and neuronal health.

The performance of halide perovskite-based electronic and optoelectronic devices is often related to interfacial charge transport. To shed light on the underlying physical and chemical properties of CH3NH3PbI3 (MAPbI3) in direct contact with common electrodes Al, Ti, Cr, Ag, and Au, the evolution of interfacial properties and Fermi level pinning is systematically studied. Given a unique experimental facility, pristine interfaces without any exposure to ambient air were prepared. We observe aggregation of substantial amounts of metallic lead (Pb0) at the metal/MAPbI3 interface, resulting from the interfacial reaction between the deposited metal and iodine ions from MAPbI3. It is found that the Schottky barrier height at the metal/MAPbI3 interface is independent of the metal work function due to strong Fermi level pinning, possibly due to the metallic Pb0 aggregates, which act as interfacial trap sites. The charge neutrality level of MAPbI3 is consistent with the energy level of Pb0-related defects, indicating that Pb0 interfacial trap states can be nonradiative recombination sites. This work underlines that control of chemical bonding at interfaces is a key factor for designing future halide perovskite-based devices.

Author(s): Babbe, F; Masquelier, E; Zheng, Z; Sutter-Fella, CM | Abstract: Wide band gap mixed halide perovskites such as MAPb(I1-xBrx)3 sparked great research interest because of their outstanding optoelectronic properties, ease of fabrication, and band gap tunability. Their application thus far is however limited by light-induced halide segregation in which microscopic clusters with a high iodide content are formed and act as recombination centers. The key mechanism(s) underlying this halide segregation process are still debated. Here, we present a study on the photoluminescence evolution in MAPb(I1.5Br1.5) perovskites with varying microstructures under constant illumination at room temperature and at elevated temperature. Our findings reveal a more complicated picture of the segregation mechanism occurring in three stages instead of two as commonly reported. The process starts with a flash formation of I-rich domains. Following is a rapid blue shift before the gradual and typically observed red shift occurs. The evolution of the three stages is fully reversible in the dark and is also present at elevated temperatures (50 °C). We explain the existence of multiple stages during light-induced halide segregation by natural compositional fluctuations of the halides and the formation of halide clusters with a dynamically changing distribution in I-Br content. The variation in the I-Br ratio depends on the grain size and film heterogeneity. These findings add further details in the quest of unraveling the underlying segregation mechanism(s), which need to be identified to stabilize halides in wide band gap perovskites.

Switzerland is one of the few European countries to apply a strict set of complex tax rules to debt financing which may even apply if a debt instrument is issued by a non-Swiss issuer. For corporate and banking lawyers involved in debt financing transactions with a nexus to Switzerland, dealing with Swiss withholding tax rules as well as the corresponding language in the loan documentation and agreements is inevitable. This article focuses on providing an overview to non-tax focused lawyers in order to facilitate the understanding of the Swiss interest withholding tax system applicable to debt financings and to raise awareness of recent changes in practice introducing more relaxed safe harbours. debt financing, Swiss withholding tax reform, tax law

All-inorganic perovskites have emerged as promising photovoltaic materials due to their superior thermal stability compared to their heat-sensitive hybrid organic-inorganic counterparts. In particular, CsPbI