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Recently, there has been significant improvement in the power conversion efficiency of non-fullerene organic solar cells, exceeding 19%. In this article, we have fabricated conventional sandwich structure of ITO/PEDOT:PSS/PM6:Y7/PDINO/Ag reaching efficiency up to 17.3% along with high generated current density of 30.60 mA/cm2 for the optimized devices. The thickness of PM6:Y7 layer has been varied to investigate the impact on the overall device behavior. The obtained results showed that the PCE has been enhanced by 15% upon reducing its thickness from 150 nm to 100 nm. Accordingly, current-voltage measurements and impedance spectroscopy analysis through capacitance-voltage, Mott-Schottky analysis and capacitance frequency under different illumination intensities were conducted to evaluate the behaviour of the charge recombination due to thickness variation of the PM6:Y7 photoactive layer.

Organic solar cells (OSCs) have reached an efficiency near 20%; however, their low long-term stability is the main limitation to their industrialization. In this work, we investigated the degradation of bulk heterojunction non-fullerene solar cells (NFA-OSCs) based on PM6:Y7 with an efficiency of 17.5%. The degradation analysis was carried out following the established ISOS-D-1 protocol under different degradation conditions: N-2 atmosphere (H2O < 0.1 ppm and O-2 < 0.1 ppm) and encapsulated devices and non-encapsulated devices exposed to ambient conditions (60 & PLUSMN; 5% relative humidity). The evolution of the current density-voltage (J-V) and impedance spectroscopy (IS) measurements were used to analyse the degradation process during 1000 h and its relationship with physical mechanisms. The degradation of encapsulated and non-encapsulated devices is mainly caused by the drop in the open circuit voltage (V-OC). For devices exposed to the N-2 atmosphere, the fill factor (FF) was the most affected parameter. The dependence of short circuit current density (J(SC)) versus light intensity study reveals that the efficiency of non-encapsulated devices decreases faster due to a higher bimolecular recombination degree. The devices under a N-2 atmosphere and those encapsulated showed T-80 lifetimes of 1000 h and 336 h, respectively, whereas the non-encapsulated devices have a short T-80 lifetime of less than 24 h. The analysis of the efficiency decay was used to identify the different degradation mechanisms (by diffused environmental water or oxygen or by intrinsic polymer chemical reactions) under different conditions. The degradation origin of the active layer and interlayers was investigated through impedance spectroscopy measurements.

A ternary strategy has been demonstrated as being an effective method to improve the power conversion efficiency (PCE); however, general rules for materials selection are not fully comprehended. Herein, nonfullerene acceptor ITIC-M and fullerene acceptor PC70BM possessing higher lowest unoccupied molecular orbital (LUMO) and good miscibility with nonfullerene acceptor Y7 are incorporated as third components in the state-of-the-art of PM6:Y7 binary blend. As a result, the device PCE for both ternary devices improves from 16.46% for binary host to 17.73% and 17.67% for ITIC-M- and PC70BM-based ternary devices, respectively. The higher LUMO of the guest acceptor can play multiple roles to elevate the open-circuit voltage such as reducing energy-loss and reverse saturation current, creating less-localized shallow trap sites along with suppressing charge recombination, and decreasing Urbach energy. Moreover, the good miscibility facilitates an alloy-like phase in acceptors domain for efficient exciton dissociation and electron transport, which leads to improved short-circuit current density and fill factor in ternary devices. The results provide a promising approach to realize high-performance ternary organic solar cells by synergizing the compatible third component with host acceptor.

The performance and industrial visibility of organic solar cells (OSCs) are greatly impacted by the functionality and stability of the interfacial layers. Many reported interface materials exhibited limitations in their fabrication temperature along with the operational stability toward the industrial up-scalability. In this work, a systematic analysis was conducted on the fresh and photo-aged-inverted non-fullerene organic solar cells (iNF-OSCs) with different structures of the electron transporting layers (ZnO, ZnO/PDINO, and PDINO), through studying their optical and electronic properties using external quantum efficiency measurements and impedance spectroscopy. Consequently, we presented PDINO as an efficient low temperature operation cathode interlayer for iNF-OSCs. Compared to the benchmark interface layers for i-OSCs such as ZnO, the PDINO interlayer used to replace the ZnO film, exhibiting a remarkable operational photostability. Where PDINO based iNF-OSCs demonstrated an extremely photostable behavior that is almost three times higher than the ZnO based devices under AM 1.5G (100 mW cm−2) continuous illumination conditions. This behavior might be attributed to the PDINO interlayer properties, which undergoes with no photochemical reaction with the contacted PM6:Y7 photo-active layer, avoiding the inescapable photocatalytic effect that is commonly obtained by the ZnO interlayer.

New experimental data are presented in this study for intermittent two and three-phase flows through horizontal pipelines involving air, water and polypropylene pellets of sizes ranging between 1 and 2 millimeters. Flow visualization and pressure measurements were performed and are explored in this work for intermittent flows. An automated image processing algorithm is developed to determine slug parameters of 59 flow conditions and compared with other measurements techniques. Correlations available in the literature for predicting slug frequency are tested with the new experimental data and curves of non-dimensional parameters are fitted to the data, the best fitting is obtained for the gas based Strouhal number against the input liquid or gas fraction. The influence of solid particles over the slug frequency is analyzed and reported. A decrease on the slug frequency is found when increasing solid concentrations. Finally, the influence of solid particles on the bubble length and velocity is investigated. A stronger influence of the gas flow rate on the velocity of the nose of the slug is observed for increasing solid concentration, together with more variability on the mean velocity. Also, longer bubbles are obtained with higher solid concentrations.

Finding an effective approach to suppress trap formation is a potential route for enhancing the performance of nonfullerene organic photovoltaic (NF-OPVs) devices. Here, an extraordinary short-circuit current density (JSC) value of 32.65 mA cm-2 is achieved, higher than the state-of-the art NF-OPVs reported, reaching a high power conversion efficiency (PCE) of 17.92%. This remarkable enhancement is exhibited through the fine-tuning of PEDOT:PSS/PM6:Y7 films and interface morphologies via applying the prethermal treatment approach (Pre-TT) to the devices, which exhibit JSC and PCE enhancement of 21% and 8%, respectively, compared to the pristine devices. Accordingly, the dependence of the JSC upon the Pre-TT approach through a range of morphological, optical, electrical, and advanced transient measurements is investigated. The Pre-TT-based films are found to possess optimal smooth blend morphology with better dispersity owing to reduced domain size. Moreover, the measurements show that the optimized treated devices present higher exciton dissociation probabilities and generation rate of the free charge carriers, showing an ideal balanced electron/hole mobility that reveals the JSC and PCE enhancement. Hence, Pre-TT approach provides a facile passivation strategy that reduces the trap state density of the blend film, improves interface charge transfer, allows balanced electron/hole mobility, and thus promotes device performance.

Morphological control of the layers within the bulk heterojunction organic photovoltaics (BHJ-OPVs) is a key feature that governs their performance. In the present work, we demonstrate that zinc oxide-ZnO-interlayers sprayed via the intermittent spray pyrolysis technique, employing a low-concentration precursor solution, can yield inverted BHJ-OPVs as efficient as the standard reported ones using the conventional laboratory-scale spin-coating technique. However, we record a pioneer stability behavior of the fabricated inverted fullerene organic photovoltaics (iF-OPVs) with various sprayed ZnO conditions. Thus, after optimizing the sprayed ZnO interfacial layer morphology for the inverted PTB7-Th:PC70BM devices, by carefully inspecting the interdependence between the sprayed ZnO thin film morphology and the figures of merit of the optimized iF-OPVs, we conducted a distinct analysis on the optical and electronic properties of the fresh and degraded devices using external quantum efficiency measurements and impedance spectroscopy. Hence, we showed that the most proper ZnO microstructural morphology was obtained by spraying 25 running cycles (25R). Remarkably, we observed that 25R-ZnO-based iF-OPV devices showed a stunning stability behavior and maintained 85% of their initial power conversion efficiency even after 16.7 months without encapsulation in a dry nitrogen glovebox, demonstrating an excellent shelf stability. Accordingly, this approach might facilitate the scalability of inverted OPVs for industrial production visibility.

In this research work, for the first time, stable high-performance inverted polymer solar cells (iPSCs) have been fabricated utilizing facile and low-cost intermittent spray pyrolysis (SP) technique to deposit transparent thin films of zinc oxide (ZnO) as electron interfacial transporting layer (ETL). The performed iPSCs have the structure of ITO/ZnO/PBDTTT-EFT:PC70BM/V2O5/Ag. The thickness diversity of the ETL layer was adjusted by varying the concentration of the ZnO precursor solution, while fixed thicknesses were fabricated for the other layers in the iPSCs. Moreover, the influence of the deposition techniques on the interface roughness, performance, and stability of the devices has been detected and discussed. By increasing the concentration of the ZnO precursor solution as well as the number of spraying running cycles, the thickness and roughness of the ZnO film increase. The highest power conversion efficiency (10%) of the fresh iPSCs with ZnO-SP was obtained by using a ZnO-precursor solution concentration of 1:4 in ethanol with 7 spraying running cycles. This efficiency is almost the same as the iPSCs fabricated ZnO-ETL by the laboratory-scale spin coating (SC) technique that was used as a reference. Furthermore, it was interesting to observe that the stability of the devices intermittently sprayed by ZnO-SP was higher than the controlled reference ones that were fabricated by ZnO-SC. Hence, deep insight studies have been carried out for the fresh and degraded iPSCs using dark current-voltage characteristics and impedance spectroscopy measurements to investigate the electrical parameters for the ZnO film obtained by the SP and SC techniques. The results indicated that the interface roughness between the ZnO and the active layers plays an important role in enhanc

Fluorinated zinc and copper metallophthalocyanines MPcF48 are synthesized and incorporated as third component small molecules in ternary organic solar cells (TOSCs). To enable the high performance of TOSCs, maximizing short-circuit current density (JSC) is crucial. Ternary bulk heterojunction blends, consisting of a polymer donor PTB7-Th, fullerene acceptors PC70BM, and a third component MPcF48, are formulated to fabricate TOSCs with a device architecture of ITO/PFN/active layer/V2O5/Ag. Employing copper as metal atom substitution in the third component of TOSCs enhances JSC as a result of complementary absorption spectra in the near-infrared region. In combination with JSC enhancement, suppressed charge recombination, improved exciton dissociation and charge carrier collection efficiency, and better morphology lead to a slightly improved fill factor (FF), resulting in a 7% enhancement of PCE than those of binary OSCs. In addition to the increased PCE, the photostability of TOSCs has also been improved by the appropriate addition of CuPcF48. Detailed studies imply that metal atom substitution in phthalocyanines is an effective way to improve JSC, FF, and thus the performance and photostability of TOSCs.

This study analyzes experimentally the deposition of magnetic beads on the walls of a square microchannel by the action of a nearby cubical magnet. The deposition has been studied for different magnetic bead sizes, flow rates, magnetic conditions and with solutions of magnetic and non‐magnetic particles. Images of the time evolution of the deposition under the different conditions have been analyzed to determine the spatial distribution of the accumulation and the growth rate of the depositions. It has been found that the way in which the magnetic beads are deposited on the walls of the microchannel depends strongly on their size and the magnetic configuration. The accumulation of the major part of particles is on the wall closest to the magnet and, depending on the size of the particles, near the magnet leading and trailing edges or near the center of the magnet. The experiments with magnetic and non‐magnetic particles revealed the screening effect of the non-magnetic particles on the deposition. In this case, the non‐magnetic particles displace the deposition toward the region near the center of the magnet and near the trailing edge.

Copyright © 2020 The Authors, some rights reserved. Closed-form, interpretable mathematical models have been instrumental for advancing our understanding of the world; with the data revolution, we may now be in a position to uncover new such models for many systems from physics to the social sciences. However, to deal with increasing amounts of data, we need machine scientists that are able to extract these models automatically from data. Here, we introduce a Bayesian machine scientist, which establishes the plausibility of models using explicit approximations to the exact marginal posterior over models and establishes its prior expectations about models by learning from a large empirical corpus of mathematical expressions. It explores the space of models using Markov chain Monte Carlo. We show that this approach uncovers accurate models for synthetic and real data and provides out-of-sample predictions that are more accurate than those of existing approaches and of other nonparametric methods.

© 2020 American Physical Society. Ever since Nikuradse's experiments on turbulent friction in 1933, there have been theoretical attempts to describe his measurements by collapsing the data into single-variable functions. However, this approach, which is common in other areas of physics and in other fields, is limited by the lack of rigorous quantitative methods to compare alternative data collapses. Here, we address this limitation by using an unsupervised method to find analytic functions that optimally describe each of the data collapses for the Nikuradse dataset. By descaling these analytic functions, we show that a low dispersion of the scaled data does not guarantee that a data collapse is a good description of the original data. In fact, we find that, out of all the proposed data collapses, the original one proposed by Prandtl and Nikuradse over 80 years ago provides the best description of the data so far, and that it also agrees well with recent experimental data, provided that some model parameters are allowed to vary across experiments.

© 2018, Biomedical Engineering Society. Purpose: Advanced morphology analysis and image-based hemodynamic simulations are increasingly used to assess the rupture risk of intracranial aneurysms (IAs). However, the accuracy of those results strongly depends on the quality of the vessel wall segmentation. Methods: To evaluate state-of-the-art segmentation approaches, the Multiple Aneurysms AnaTomy CHallenge (MATCH) was announced. Participants carried out segmentation in three anonymized 3D DSA datasets (left and right anterior, posterior circulation) of a patient harboring five IAs. Qualitative and quantitative inter-group comparisons were carried out with respect to aneurysm volumes and ostia. Further, over- and undersegmentation were evaluated based on highly resolved 2D images. Finally, clinically relevant morphological parameters were calculated. Results: Based on the contributions of 26 participating groups, the findings reveal that no consensus regarding segmentation software or underlying algorithms exists. Qualitative similarity of the aneurysm representations was obtained. However, inter-group differences occurred regarding the luminal surface quality, number of vessel branches considered, aneurysm volumes (up to 20%) and ostium surface areas (up to 30%). Further, a systematic oversegmentation of the 3D surfaces was observed with a difference of approximately 10% to the highly resolved 2D reference image. Particularly, the neck of the ruptured aneurysm was overrepresented by all groups except for one. Finally, morphology parameters (e.g., undulation and non-sphericity) varied up to 25%. Conclusions: MATCH provides an overview of segmentation methodologies for IAs and highlights the variability of surface reconstruction. Further, the study emphasizes the need for c

Europium-doped La2O3 nanocrystalline powders with sizes ranging from 4 nm to 300 nm have been obtained by the modified Pechini, hydrothermal with conventional furnace, hydrothermal with microwave furnace, and precipitation with ultrasonic bath methods. X-ray diffraction techniques were used to study the evolution of the prepared gels towards the desired crystalline phase. We determined the size and the morphology of the nanoparticles by electronic microscopy. Finally, we studied and analyzed the luminescence properties of the trivalent europium in the hexagonal La2O3 nanocrystals by photoluminescence and cathodoluminescence.

Job satisfaction in health services is measured by the quality oAbstract: The present study evaluates how psychosocial group climate and personality affects burnout syndrome (BS) in teachers of infant, primary and secondary education. To do so questionnaires were administered to evaluate psychosocial climate, personality and burnout in a sample of 386 teachers. The study analyzes the relation between these variables and the extent to which the variables of climate and personality allow a predictive model of burnout to be established by means of multiple regression analysis. The results showed that both psychosocial climate (particularly the degree of disorganization) and personality (particularly emotional stability) influence burnout and, although climate factors seem to be better predictors of BS, the use of personality measurements increases the predictive capacity of the syndrome. Therefore, the joint use of these types of predictor in-creases our ability to establish models that can prevent BS in teaching environments. © 2015, Servicio de Publicaciones de la Universidad de Murcia.

© 2014, Formentín et al.; licensee Springer. Human aortic endothelial cells play a key role in the pathogenesis of atherosclerosis, which is a common, progressive, and multifactorial disease that is the clinical endpoint of an inflammatory process and endothelial dysfunction. Study and development of new therapies against cardiovascular disease must be tested in vitro cell models, prior to be evaluated in vivo. To this aim, new cell culture platforms are developed that allow cells to grow and respond to their environment in a realistic manner. In this work, the cell adhesion and morphology of endothelial cells are investigated on functionalized porous silicon substrates with two different pore size configurations: macroporous and nanoporous silicon. Herein, we modified the surfaces of porous silicon substrates by aminopropyl triethoxysilane, and we studied how different pore geometries induced different cellular response in the cell morphology and adhesion. The cell growth over the surface of porous silicon becomes an attractive field, especially for medical applications. Surface properties of the biomaterial are associated with cell adhesion and as well as, with proliferation, migration and differentiation.

10.1186/1556-276X-8-385, We report the formation of two-dimensional disordered arrays of poly(methyl)methacrylate (PMMA) microcolumns with embedded single size distribution of Lu0.990Er0.520Yb0.490 nanocrystals, (Er,Yb):Lu2O3, using a disordered porous silicon template. The cubic (Er,Yb):Lu2O3 nanocrystals, which crystallize into the cubic system with Ia3¯ space group, were synthesized using the modified Pechini method. Electronic microscopic techniques were used to study the distribution of the nanocrystals in the PMMA columns. Cathodoluminescence was used to observe the visible luminescence of the particles. Red emission attributed to 4 F9/2 → 4I15/2 erbium transition is predominant in these new composites.

10.1063/1.4788819, By means of ?nite-element numerical modeling, we analyze the in?uence of the nanostructured dissociation interface geometry on the behavior of interdigitated heterojunction full organic solar cells. A systematic analysis of light absorption, exciton diffusion, and carrier transport, all in the same numerical framework, is carried out to obtain their dependence on the interface geometrical parameters: pillar diameter and height, and nanostructure period. Cells are constituted of poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61. Results show that light absorption is maximum for pillar heights of 80 nm and 230 nm. However, due to the short exciton diffusion length of organic materials, the analysis of the exciton diffusion process reveals that the 80 nm thickness gives rise to a higher photocurrent, except for the smaller pillar diameters. In terms of ef?ciency, it has been observed that the charge carrier transport is weakly dependent on the geometric parameters of the nanostructured interface if compared with the exciton diffusion process. The optimal cell is a device with a pillar height of 80 nm, a structure period of 25 nm, and a ratio of the nanopillar diameter to the period of 0.75, with an ef?ciency 3.6 times higher than the best planar bilayer reference device. This structure is such that it reaches a compromise between having a high proportion of P3HT to increase light absorption but preserving a small pillar diameter and interpillar distance to ensure an extended exciton dissociation interface.

10.1016/j.clay.2013.05.006, Friedel's salt [Ca2Al(OH)6]Cl·2H2O, commonly known as hydrocalumite, was synthesized by co-precipitation following different aging treatments, using microwave irradiation or conventional heating and by refluxing or in autoclave, with the aim of decreasing the aging times (24 h) employed when aging by conventional heating or at room temperature. Hydrocalumites were characterized by XRPD, FT-IR, N2 physisorption, ICP-OES, TEM, TEM-electron diffraction and TGA techniques. The use of microwaves favors a faster crystalline growth in the stacking direction whereas the use of autoclave improves the lamellar crystallinity. The highest crystallinity was found for the sample aged with microwave irradiation by autoclaving at 453 K for 1 h. This sample presented the highest crystallite size in the stacking direction (76 nm), the largest lamellar crystals (4000 nm) with R3c symmetry, and the highest dehydration- and dehydroxylation temperatures.

10.1186/1556-276X-7-228, We report on an exhaustive and systematic study about the photoluminescent properties of nanoporous anodic alumina membranes fabricated by the one-step anodization process under hard conditions in oxalic and malonic acids. This optical property is analysed as a function of several parameters (i.e. hard anodization voltage, pore diameter, membrane thickness, annealing temperature and acid electrolyte). This analysis makes it possible to tune the photoluminescent behaviour at will simply by modifying the structural characteristics of these membranes. This structural tuning ability is of special interest in such fields as optoelectronics, in which an accurate design of the basic nanostructures (e.g. microcavities, resonators, filters, supports, etc.) yields the control over their optical properties and, thus, upon the performance of the nanodevices derived from them (biosensors, interferometers, selective filters, etc.)