Robust Dipolar Layers between Organic Semiconductors and Silver for Energy-Level Alignment

The interface between a metal electrode and an organic semiconductor (OS) layer has a defining role in the properties of the resulting device. To obtain the desired performance, interlayers are introduced to modify the adhesion and growth of OS and enhance the efficiency of charge transport through the interface. However, the employed interlayers face common challenges, including a lack of electric dipoles to tune the mutual position of energy levels, being too thick for efficient electronic transport, or being prone to intermixing with subsequently deposited OS layers. Here, we show that monolayers of 1,3,5-tris(4-carboxyphenyl)benzene (BTB) with fully deprotonated carboxyl groups on silver substrates form a compact layer resistant to intermixing while capable of mediating energy-level alignment and showing a large insensitivity to substrate termination. Employing a combination of surface-sensitive techniques, i.e., low-energy electron microscopy and diffraction, X-ray photoelectron spectroscopy, and scanning tunneling microscopy, we have comprehensively characterized the compact layer and proven its robustness against mixing with the subsequently deposited organic semiconductor layer. Density functional theory calculations show that the robustness arises from a strong interaction of carboxylate groups with the Ag surface, and thus, the BTB in the first layer is energetically favored. Synchrotron radiation photoelectron spectroscopy shows that this layer displays considerable electrical dipoles that can be utilized for work function engineering and electronic alignment of molecular frontier orbitals with respect to the substrate Fermi level. Our work thus provides a widely applicable molecular interlayer and general insights necessary for engineering of charge injection layers for efficient organic electronics.

Effects of dietary energy levels on microorganisms and short-chain fatty acids of rumen and tight junction proteins in Honghe Yellow cattle

This study was conducted to investigate the effects of dietary energy levels on microorganisms and short-chain fatty acids (SCFAs) of rumen and the expression of tight junction proteins in Honghe Yellow cattle. A total of fifteen male Honghe Yellow cattle were randomly divided into three treatments (five replicates per treatment), consisting of formulated energy concentrations of 5.90 MJ/kg (high-energy diet, group H), 5.60 MJ/kg (medium-energy diet, group M) and 5.30 MJ/kg (low-energy diet, group L). The results showed that compared with group H, the expression of Claudin-1 in rumen epithelium of groups M and L was increased, but the expression of ZO-1 was decreased (p < 0.05). Moreover, compared with group H, group M down-regulated the expression of Occludin and Claudin-1 in the brain (p < 0.05). For rumen bacteria, the dominant phyla included Bacteroidetes and Firmicutes, the abundance of Actinobacteriota in groups M and L was significantly increased compared with group H (p < 0.05). At the genus level, the relative abundance of Corynebacterium, Eubacterium_nodatum_group and Neisseraceae in groups M and L was significantly decreased compared with group H (p < 0.05). For rumen fungi, the dominant phyla included Basidiomycota, Ascomycota and Neocariastigomycota, the relative abundance of Ascomycetes was significantly higher than that of groups M and L compared with group H (p < 0.05). At the genus level, the relative abundance of Neocelimastigaceae and Myceliophthora in groups M and L was significantly reduced compared with group H (p < 0.05). Furthermore, the expression of Claudin-1 in rumen epithelium was significantly positively correlated with Actinobacteriota, Corynebacterium and Neisseriaceae. The expression of ZO-1 in the spinal cord was significantly positively correlated with Myceliophthora. The expression of Occludin in brain was positively correlated with valerate content (p < 0.05). In summary, dietary energy levels affected the rumen microbiota of Honghe Yellow cattle. The expression of Claudin-1 in rumen epithelium and the total SCFAs concentration were increased with decreasing dietary energy levels, but the expression of Claudin-1 in brain and ZO-1 in the spinal cord were reduced with decreasing dietary energy levels. Meanwhile, the rumen microbiota and SCFAs were significantly correlated with the expression of TJP.

Deciphering the Effects of Molecular Dipole Moments on the Photovoltaic Performance of Organic Solar Cells

The dielectronic constant of organic semiconductor materials is directly related to its molecule dipole moment, which can be used to guide the design of high-performance organic photovoltaic materials. Herein, two isomeric small molecule acceptors, ANDT-2F and CNDT-2F, are designed and synthesized by using the electron localization effect of alkoxy in different positions of naphthalene. It is found that the axisymmetric ANDT-2F exhibits a larger dipole moment, which can improve exciton dissociation and charge generation efficiencies due to the strong intramolecular charge transfer effect, resulting in the higher photovoltaic performance of devices. Moreover, PBDB-T:ANDT-2F blend film exhibits larger and more balanced hole and electron mobility as well as nanoscale phase separation due to the favorable miscibility. As a result, the optimized device based on axisymmetric ANDT-2F shows a JSC of 21.30 mA cm-2 , an FF of 66.21%, and a power conversion energy of 12.13%, higher than that of centrosymmetric CNDT-2F-based device. This work provides important implications for designing and synthesizing efficient organic photovoltaic materials by tuning their dipole moment.

Control of Bandgaps and Energy Levels in Water-Soluble Discontinuously Conjugated Polymers through Chemical Modification

Bandgap and energy levels are crucial for developing new electronic and photonic devices because photoabsorption is highly dependent on the bandgap. Moreover, the transfer of electrons and holes between different materials depends on their respective bandgaps and energy levels. In this study, we demonstrate the preparation of a series of water-soluble discontinuously π-conjugated polymers through the addition-condensation polymerization of pyrrole (Pyr), 1,2,3-trihydroxybenzene (THB) or 2,6-dihydroxytoluene (DHT), and aldehydes, including benzaldehyde-2-sulfonic acid sodium salt (BS) and 2,4,6-trihydroxybenzaldehyde (THBA). To control the energy levels of the polymers, varying amounts of phenols (THB or DHT) were introduced to alter the electronic properties of the polymer structure. The introduction of THB or DHT into the main chain results in discontinuous conjugation and enables the control of both the energy level and bandgap. Chemical modification (acetoxylation of phenols) of the polymers was employed to further tune the energy levels. The optical and electrochemical properties of the polymers were also investigated. The bandgaps of the polymers were controlled in the range of 0.5-1.95 eV, and their energy levels could also be effectively tuned.

MXene Contact Engineering for Printed Electronics

MXenes emerging as an amazing class of 2D layered materials, have drawn great attention in the past decade. Recent progress suggest that MXene-based materials have been widely explored as conductive electrodes for printed electronics, including electronic and optoelectronic devices, sensors, and energy storage systems. Here, the critical factors impacting device performance are comprehensively interpreted from the viewpoint of contact engineering, thereby giving a deep understanding of surface microstructures, contact defects, and energy level matching as well as their interaction principles. This review also summarizes the existing challenges of MXene inks and the related printing techniques, aiming at inspiring researchers to develop novel large-area and high-resolution printing integration methods. Moreover, to effectually tune the states of contact interface and meet the urgent demands of printed electronics, the significance of MXene contact engineering in reducing defects, matching energy levels, and regulating performance is highlighted. Finally, the printed electronics constructed by the collaborative combination of the printing process and contact engineering are discussed.

Well-Defined Fullerene Bisadducts Enable High-Performance Tin-Based Perovskite Solar Cells

Tin-based perovskite solar cells (TPSCs) are attracting intense research interest due to their excellent optoelectric properties and eco-friendly features. To further improve the device performance, developing new fullerene derivatives as electron transporter layers (ETLs) is highly demanded. Four well-defined regioisomers (trans-2, trans-3, trans-4, and e) of diethylmalonate-C₆₀ bisadduct (DCBA) are isolated and well characterized. The well-defined molecular structure enables us to investigate the real structure-dependent effects on photovoltaic performance. It is found that the chemical structures of the regioisomers not only affect their energy levels, but also lead to significant differences in their molecular packings and interfacial contacts. As a result, the devices with trans-2, trans-3, trans-4, and e as ETLs yield efficiencies of 11.69%, 14.58%, 12.59%, and 10.55%, respectively, which are higher than that of the as-prepared DCBA-based (10.28%) device. Notably, the trans-3-based device also demonstrates a certified efficiency of 14.30%, representing one of the best-performing TPSCs.

Quantum Mechanical Analysis Based on Perturbation Theory of CdSe/ZnS Quantum-Dot Light-Emission Properties

A simulation of quantum dot (QD) energy levels was designed to reproduce a quantum mechanical analytic method based on perturbation theory. A Schrödinger equation describing an electron-hole pair in a QD was solved, in consideration of the heterogeneity of the material parameters of the core and shell. The equation was solved numerically using single-particle basis sets to obtain the eigenstates and energies. This approach reproduced an analytic solution based on perturbation theory, while the calculation was performed using a numerical method. Owing to the effectiveness of the method, QD behavior according to the core diameter and external electric field intensity could be investigated reliably and easily. A 9.2 nm diameter CdSe/ZnS QD with a 4.2 nm diameter core and 2.5 nm thick shell emitted a 530 nm green light, according to an analysis of the effects of core diameter on energy levels. A 4 nm redshift at 5.4×105 V/cm electric field intensity was found while investigating the effects of external electric field on energy levels. These values agree well with previously reported experimental results. In addition to the energy levels and light emission wavelengths, the spatial distributions of wavefunctions were obtained. This analysis method is widely applicable for studying QD characteristics with varying structure and material compositions and should aid the development of high-performance QD technologies.

Update of Atomic Data for the First Three Spectra of Actinium

The present article describes a complete reanalysis of all published data on observed spectral lines and energy levels of the first three spectra of actinium (Ac I-III). In Ac I, three previously determined energy levels have been rejected, 12 new energy levels have been found; for six previously known levels, either the J values or the energies have been revised, and the ionization energy has been redetermined with an improved accuracy. In the line list of Ac I, three previous classifications have been discarded, 16 new ones have been found, and three have been revised. In Ac II, 16 new energy levels have been established, and 36 new identifications have been found for previously observed but unclassified lines. In both Ac I and Ac II, new sets of transition probabilities have been calculated. For all three spectra, complete datasets of critically evaluated energy levels, observed lines, and transition probabilities have been constructed to serve as recommended data on these spectra.

Near-Infrared Nonfullerene Acceptors Based on 4H-Cyclopenta[1,2-b:5,4-b']dithiophene for Organic Solar Cells and Organic Field-Effect Transistors

The development of nonfullerene small molecular acceptors (NF-SMAs) has dominated the improvement of efficiencies for organic solar cells and the near-infrared (NIR) absorption is the primary feature of NF-SMAs compared with fullerene derivatives. In this article, a series of acceptor-donor-acceptor-structured NF-SMAs (named CPICs) containing 4H-cyclopenta[1,2-b : 5,4-b']dithiophene (CPDT) electron donor and F-substituted 2-(3-oxo-2,3-dihydro-1H-inden-1-ylidene)malononitrile (2FIC) as electron acceptor were designed and synthesized. With the increase of CPDT units, the elongated conjugations broadened the absorption range of the acceptors and tuned their energy levels sequentially. Therefore, their charge-transporting polarities switched from electron-only type to bipolar mode in organic field-effect transistors. Moreover, these changes also influenced the voltages, current densities, and eventual PCEs of their corresponding cells. When blending with PBDB-T, a champion efficiency of 10.01% was achieved in CPIC-2 based cells. This work demonstrated the importance of absorptions, suitable energy levels and charge transports in improving the efficiencies of organic solar cells.

Review of Organic Photorefractive Materials and Their Use for Updateable 3D Display

Photorefractive materials are capable of reversibly changing their index of refraction upon illumination. That property allows them to dynamically record holograms, which is a key function for developing an updateable holographic 3D display. The transition from inorganic photorefractive crystals to organic polymers meant that large display screens could be made. However, one essential figure of merit that needed to be worked out first was the sensitivity of the material that enables to record bright images in a short amount of time. In this review article, we describe how polymer engineering was able to overcome the problem of the material sensitivity. We highlight the importance of understanding the energy levels of the different species in order to optimize the efficiency and recording speed. We then discuss different photorefractive compounds and the reason for their particular figures of merit. Finally, we consider the technical choices taken to obtain an updateable 3D display using photorefractive polymer. By leveraging the unique properties of this holographic recording material, full color holograms were demonstrated, as well as refreshing rate of 100 hogels/second.

Benzobis(Thiazole)-Based Conjugated Polymer with Varying Alkylthio Side-Chain Positions for Efficient Fullerene-Free Organic Solar Cells

Alkylthio groups can be used to modulate energy levels and molecular packing of organic semiconductors, which makes it important in the design of materials for organic solar cell. However, its effect has not been sufficiently exploited as most of the studies report introducing an alkylthio group to the donor unit and seldom to the acceptor unit of donor-acceptor conjugated polymers. In this report, two alkylthio-substituted polymers, namely, PBB-TSA and PBB-TSD, with benzo[1,2-d:4,5-d']bis(thiazole) (BBT) as the acceptor unit and benzo[1,2-b:4,5-b']dithiophene (BDT) as the donor unit, were rationally designed, synthesized, and applied in organic photovoltaics. An alkylthio side chain was substituted on the BBT-accepting unit for PBB-TSA, while for PBB-TSD, the alkylthio side chain was substituted on the BDT donor unit. PBB-TSA and PBB-TSD show upshifted and downshifted energy levels, respectively, compared to the nonsulfur-substituted material. Both polymers exhibit dominate face-on orientation, while PBB-TSD exhibits higher crystallinity compared to PBB-TSA. With the contribution of lower energy level and beneficial film morphology, the device based on PBB-TSD/IT-4F has much higher power conversion efficiency (PCE) of 14.6%, whereas the PBB-TSA blend had a lower PCE of 10.7%. 1,8-Diiodooctane can effectively optimize the blend film morphology, and the effect on device performance has also been demonstrated in detail. This result indicates that introducing an alkylthio side chain into the donor or acceptor moieties would result in materials with different energy levels and thus would be utilized to match with various acceptors, achieving optimized performance in organic solar cells.

Influence of Pumping Regime on Temperature Resolution in Nanothermometry

In recent years, optical nanothermometers have seen huge improvements in terms of precision as well as versatility, and several research efforts have been directed at adapting novel active materials or further optimizing the temperature sensitivity. The signal-to-noise ratio of the emission lines is commonly seen as the only limitation regarding high precision measurements. The role of re-absorption caused by a population of lower energy levels, however, has so far been neglected as a potential bottleneck for both high resolution and material selection. In this work, we conduct a study of the time dependent evolution of population densities in different luminescence nanothermometer classes under the commonly used pulsed excitation scheme. It is shown that the population of lower energy levels varies when the pump source fluctuates in terms of power and pulse duration. This leads to a significant degradation in temperature resolution, with limiting values of 0.5 K for common systems. Our study on the error margin indicates that either short pulsed or continuous excitation should be preferred for high precision measurements. Additionally, we derive conversion factors, enabling the re-calibration of currently available intensity ratio measurements to the steady state regime, thus facilitating the transition from pulse regimes to continuous excitation.

Highly Efficient Electrofluorescence Material Based on Pure Organic Phosphor Sensitization*

Pure organic room-temperature phosphorescence (RTP) materials are considered as potential candidates for replacing precious metal complexes to fabricate highly efficient organic light-emitting devices (OLEDs). However, applications of the reported RTP materials in OLEDs are seriously impeded by their low photoluminescence quantum yields (PLQYs) in a thin film state. To overcome these obstacles, we established a new strategy to construct highly efficient OLEDs based on a pure organic RTP material sensitized fluorescence emitter by selecting benzimidazole-triazine molecules (PIM-TRZ), 2,6-di(phenothiazinyl)naphthalene (β-DPTZN), and 5,6,11,12-tetraphenylnaphthacene (rubrene) as host, phosphor sensitizer, and fluorescent emitter, respectively. The perfect combination of host, phosphorescent sensitizer, and fluorescent emitter in the emitting layer ensure the outstanding performance of the devices with an external quantum efficiency (EQE) of 15.7 %.

An Effective Strategy to Design a Large Bandgap Conjugated Polymer by Tuning the Molecular Backbone Curvature

With the significant progress of low bandgap non-fullerene acceptors, the development of wide bandgap (WBG) donors possessing ideal complementary absorption is of crucial importance to further enhance the photovoltaic performance of organic solar cells. An ideal strategy to design WBG donors is to down-shift the highest occupied molecular orbital (HOMO) and up-shift the lowest unoccupied molecular orbital (LUMO). A properly low-lying HOMO of the donor is favorable to obtaining a high open-circuit voltage, and a properly high-lying LUMO of the donor is conductive to efficient exciton dissociation. This work provides a new strategy to enlarge the bandgap of a polymer with simultaneously decreased HOMO and increased LUMO by increasing the polymer backbone curvature. The polymer PIDT-fDTBT with a large molecular backbone curvature shows a decreased HOMO of -5.38 eV and a prominently increased LUMO of -3.35 eV relative to the linear polymer PIDT-DTBT (E_HOMO = -5.30 eV, E_LUMO = -3.55 eV). The optical bandgap of PIDT-fDTBT is obviously broadened from 1.75 to 2.03 eV. This work demonstrates that increasing the polymer backbone curvature can effectively broaden the bandgap by simultaneously decreasing HOMO and increasing LUMO, which may guide the design of WBG conjugated materials.

High-Efficiency Perovskite Solar Cells with Imidazolium-Based Ionic Liquid for Surface Passivation and Charge Transport

Surface defects have been a key constraint for perovskite photovoltaics. Herein, 1,3-dimethyl-3-imidazolium hexafluorophosphate (DMIMPF₆ ) ionic liquid (IL) is adopted to passivate the surface of a formamidinium-cesium lead iodide perovskite (Cs_0.08 FA_0.92 PbI₃ ) and also reduce the energy barrier between the perovskite and hole transport layer. Theoretical simulations and experimental results demonstrate that Pb-cluster and Pb-I antisite defects can be effectively passivated by [DMIM]⁺ bonding with the Pb²⁺ ion on the perovskite surface, leading to significantly suppressed non-radiative recombination. As a result, the solar cell efficiency was increased to 23.25 % from 21.09 %. Meanwhile, the DMIMPF₆ -treated perovskite device demonstrated long-term stability because the hydrophobic DMIMPF₆ layer blocked moisture permeation.

Effects of dietary energy levels on performance and carcass yield of 2 meat-type broiler lines housed in hot and cool ambient temperatures

Two meat-type broiler lines, line A and line B were fed experimental diets from 22-42 d with objectives to determine the effects of dietary metabolizable energy (ME) levels on feed intake (FI), performance, body composition, and processing yield as affected by environmental grow-out temperatures. Two thousand fifty male chicks from line A and 2,050 male chicks from line B were reared in 90-floor pens, 45 chicks per pen utilizing primary breeder nutrition and husbandry guidelines for starter (1-10 d) and grower (11-21 d) phases. Experimental finisher diets consisted of 5 increasing levels of apparent nitrogen corrected ME (2,800, 2,925, 3,050, 3,175, and 3,300 kcal/kg set at 19.5% crude protein and 1.0% dLys at each level) to represent 80, 90, 100, 110, and 120% ME of Evonik AminoChick energy level giving 2 × 5 factorial design and were fed from 22-42 d. All other amino acid levels in diets were formulated to a fixed ratio of dLys level. There were nine replicate pens for each diet and each line. The experiment was conducted twice-once in hot season (barn averages: 77.55 ˚F and 86.04% RH) and another in cool season (barn averages: 69.91 ˚F and 63.98% RH) of the year. Results showed that FI and feed conversion ratios (FCR) decreased (P < 0.05) linearly (R² = 0.9) by 61.25 g and 0.073 units for every 10% increase in dietary ME for combined analysis of lines and seasons. The % fat mass of total body mass increased by 0.57%, whereas % protein mass decreased by 0.21% across ME levels (R² > 0.9). However, there was no difference (P > 0.05) in % weights (of live weight) for wings, breast filet, tenders, or leg quarters across ME levels for both lines except % fat pad that increased (P < 0.05) by 0.20% for each 10% increment in dietary ME level. Line B had higher cumulative FI, BW gain, % lean, and protein mass of body mass than line A in hot season (P < 0.05). Feed intake was not different between lines in cool season (P > 0.05), whereas higher BW and improved FCR were observed for line A. Line A had higher % fat mass in both seasons. In summary, performance and yield results as affected by dietary ME levels were line specific and were affected by grow-out seasons. The optimal dietary ME level for the ME range studied (2,800-3,000 kcal/kg) at a constant recommended amino acid level lies in determining the best performance and profitability indices by taking into account the grow-out production inputs and processing yield outputs.

Theoretical Investigation on Photophysical Properties of Triphenylamine and Coumarin Dyes

Organic molecules with donor and acceptor configures are widely used in optoelectronic materials. Triphenylamine dyes (TPCTh and TPCRh) are investigated via density functional theory (DFT) and time-dependent DFT. Some microscopic parameters related to light absorption and photoelectric formation are calculated to interpret the experimental performance in dye-sensitized solar cells (DSSCS). Considering that coumarin derivatives (Dye 10 and Dye 11) have good donor and acceptor structures, they also have a COOH group used as an anchoring group to connect with semiconductors. Thus, the two dyes' photophysical and photoelectric properties are analyzed to estimate the performance and application in DSSCs.

Perylene Diimide-Based Conjugated Polymers for All-Polymer Solar Cells

In recent decades, non-fullerene acceptors (NFAs) are undergoing rapid development and emerging as a hot area in the field of organic solar cells. Among the high-performance non-fullerene acceptors, aromatic diimide-based electron acceptors remain to be highly promising systems. This review discusses the important progress of perylene diimide (PDI)-based polymers as non-fullerene acceptors in all-polymer solar cells (all-PSCs) since 2014. The relationship between structure and property, matching aspects between donors and acceptors, and device fabrications are unveiled from a synthetic chemist perspective.

Chlorination: An Effective Strategy for High-Performance Organic Solar Cells

This work summarizes recent developments in polymer solar cells (PSCs) prepared by a chlorination strategy. The intrinsic property of chlorine atoms, the progress of chlorinated polymers and small molecules, and the synergistic effect of chlorination with other methods to elevate solar conversions are discussed. Halogenation of donor-acceptor (D-A) materials is an effective method to improve the performance of PSCs, which mainly affects the push-pull of electrons between donor and acceptor units due to their strong electron-withdrawing capabilities. Although chlorine is less electronegative than fluorine, it can form very strong noncovalent interactions, such as Cl···S and Cl···π interactions, because its empty 3d orbits can help to accept the electron pairs or π electrons. This synergistic effect of electronegativity together with the empty 3d orbits of chlorine atoms leads to increased intramolecular and intermolecular interactions and a much stronger capability to down-shift the molecular energy levels. This work is intended to support a better understanding of the chlorination strategy to modify the material properties, and thus improve the performance of solar devices. Eventually, it will provide the research community with a clearer pathway to choose proper substitution methods according to different situations for high and stable solar energy conversion.

Reducing Detrimental Defects for High-Performance Metal Halide Perovskite Solar Cells

In several photovoltaic (PV) technologies, the presence of electronic defects within the semiconductor band gap limit the efficiency, reproducibility, as well as lifetime. Metal halide perovskites (MHPs) have drawn great attention because of their excellent photovoltaic properties that can be achieved even without a very strict film-growth control processing. Much has been done theoretically in describing the different point defects in MHPs. Herein, we discuss the experimental challenges in thoroughly characterizing the defects in MHPs such as, experimental assignment of the type of defects, defects densities, and the energy positions within the band gap induced by these defects. The second topic of this Review is passivation strategies. Based on a literature survey, the different types of defects that are important to consider and need to be minimized are examined. A complete fundamental understanding of defect nature in MHPs is needed to further improve their optoelectronic functionalities.

Physical activity-related quality of life in breast cancer survivors compared to healthy women

OBJECTIVE

To evaluate physical activity-related quality of life (PAQOL) in breast cancer survivors compared to healthy women.

METHODS

Physical activity level was measured as not active, somewhat active, active or very active. Intensity was reported as hours per week of light, moderate and vigorous activity. Physical activity-related quality of life was measured with the Vitality Plus Scale, a self-report instrument developed and validated to measure exercise-related health benefits.

RESULTS

Compared to healthy women (n = 23), breast cancer survivors (n = 23) were older (57.0 ± 2.3 vs. 49.0 ± 1.1 years; p < .01) and reported more light activity (4.1 ± 0.6 vs. 2.4 ± 0.5 hr/week; p < .05), but no differences in PAQOL. However, when grouped by physical activity level there were no differences in age, but inactive women (n = 30) had higher body mass index (29.3 ± 1.0 vs. 25.1 ± 1.1 kg/m² ; p < .05) and reported less moderate (1.3 ± 0.4 vs. 3.6 ± 0.8 hr/week; p < .05) and vigorous (0.2 ± 0.1 vs. 1.9 ± 0.5 hr/week; p < .01) activity than active women (n = 16). Furthermore, active women reported higher overall PAQOL, greater energy levels and quicker sleep onset than inactive women (p < .05).

CONCLUSIONS

In these women, moderate and vigorous physical activity and PAQOL were not influenced by breast cancer survivorship. Despite diagnosis, active women who engaged in greater amounts of moderate and vigorous activity reported better PAQOL than inactive women.

Strain Effects on the Energy-Level Alignment at Metal/Organic Semiconductor Interfaces

Flexible and wearable devices are among the upcoming trends in the opto-electronics market. Nevertheless, bendable devices should ensure the same efficiency and stability as their rigid analogs. It is well-known that the energy barriers between the metal Fermi energy and the molecular levels of organic semiconductors devoted to charge transport are key parameters in the performance of organic-based electronic devices. Therefore, it is paramount to understand how the energy barriers at metal/organic semiconductor interfaces change with bending. In this work, we experimentally measure the interface energy barriers between a metallic contact and small semiconducting molecules. The measurements are performed in operative conditions, while the samples are bent by a controlled applied mechanical strain. We determine that energy barriers are not sensitive to bending of the sample, but we observe that the hopping transport of the charges in flat molecules can be tuned by mechanical strain. The theoretical model developed for this work confirms our experimental observations.

Recent Progress in Fused-Ring Based Nonfullerene Acceptors for Polymer Solar Cells

The progress of bulk-heterojunction (BHJ) polymer solar cells (PSCs) is closely related to the innovation of photoactive materials (donor and acceptor materials), interface engineering, and device optimization. Especially, the development of the photoactive materials dominates the research filed in the past decades. Photoactive materials are basically classified as p-type organic semiconductor donor (D) and an n-type organic semiconductor acceptor (A). In the past two decades, fullerene derivatives are the dominant acceptors for high efficiency PSCs. Nevertheless, the limited absorption and challenging structural tunability of fullerenes hinder further improve the efficiency of PSCs. Encouragingly, the recent progresses of fused-ring based A-D-A type nonfullerene acceptors exhibit great potential in enhancing the photovoltaic performance of devices, driving the power conversion efficiency to over 13%. Such kind of nonfullerene acceptors is usually based on indacenodithiophene (IDT) or its extending backbone core and end-caped with strong electron-withdrawing group. Owing to the strong push-pulling effects, the acceptors possess strong absorption in the visible-NIR region and low-lying HOMO (highest occupied molecular orbital) level, which can realize both high open-circuit voltage and short-circuit current density of the devices. Moreover, the photo-electronic and aggregative properties of the acceptors can be flexibly manipulated via structural design. Many strategies have been successfully employed to tune the energy levels, absorption features, and aggregation properties of the fused-ring based acceptors. In this review, we will summarize the recent progress in developing highly efficient fused-ring based nonfullerene acceptors. We will mainly focus our discussion on the correlating factors of molecular structures to their absorption, molecular energy levels, and photovoltaic performance. It is envisioned that an analysis of the relationship between molecular structures and photovoltaic properties would contribute to a better understanding of this kind of acceptors for high-efficiency PSCs.

Suppressed Interfacial Charge Recombination of PbS Quantum Dot Photovoltaics by Graphene Incorporated into ZnO Nanoparticles

Single-layer graphene (SLG) was incorporated into ZnO nanoparticles (NPs), and use of this material in photovoltaic devices generated significant changes. The Fermi level of ZnO NPs underwent a downshift, whereas the conduction and valence bands were maintained with increasing SLG concentrations. Furthermore, the effective defect densities were reduced and carrier mobility was enhanced. Colloidal quantum dot photovoltaics (CQDPVs) with the SLG-incorporated ZnO NP layer as an electron transporting layer achieved significant performance enhancement. Poor performing CQDPVs were also observed with incorporation of an excess amount of SLG. This trend paralleled the interfacial charge recombination trends of CQDPVs. Effective suppression of interfacial recombination was achieved for CQDPVs with an appropriate SLG concentration, whereas dramatically increased interfacial recombination was observed for CQDPVs with an excess of SLG. For CQDPVs with appropriate SLG incorporation, efficient defect passivation and enhanced electron mobility of ZnO NPs facilitated loss-less electron transfer and efficient electron extraction without compromising the favorable energy level alignment. Excess SLG incorporation led to an increase in recombination within the PbS QD layer due to the presence of an energy barrier. This simple and powerful strategy provides an effective method for modulating the interfacial properties of CQDPVs.

Visible-Light Photoinduced Electron Transfer Promoted by Cucurbit[8]uril-Enhanced Charge Transfer Interaction: Toward Improved Activity of Photocatalysis

Visible-light photoinduced electron transfer (Vis-PET) is highly important for optoelectronic devices and photoredox catalysis. Herein, we propose a supramolecular strategy to promote the Vis-PET process by charge transfer (CT) interactions. As a proof of concept, a molecular system containing 1,5-alkoxy-substituted naphthalene and viologen moieties was designed to form a CT complex in water. The HOMO/LUMO energy gap was lowered by CT interaction, which turned on the Vis-PET process to generate viologen radical cations. Moreover, when CT interaction was enhanced by cucurbit[8]uril, the efficiency of the Vis-PET process was further promoted and the required irradiation wavelength could be further red-shifted by 100 nm. The Vis-PET system exhibited an improved activity of photocatalysis, as supported by the fast photoreduction of Cytochrome c. This study represents a facile supramolecular way to fabricate radicals with maintained activity under mild conditions, which holds potential to enrich the scope of visible-light photoredox catalysis by the rational utilization of CT systems.

Structural Evolutions and Crystal Field Characterizations of Tm-Doped YAlO3: New Theoretical Insights

The recent renaissance of the use of rare-earth-doped yttrium orthoaluminate as an ideal laser material has generated significant interest; however, the unique structural features underlying many of its outstanding optical properties still require elucidation. To solve this intriguing problem, we performed a systematic first-principles study; the results of the study reveal a new stable phase for Tm³⁺-doped YAlO₃ (YAP), of monoclinic Pm symmetry, with an 80-atom per unit cell. An unbiased CALYPSO structure search indicates that the Tm³⁺ impurity ion tends to substitute the position of Y³⁺ in the YAP crystal lattice. Electronic band structure calculations reveal that the insulated behaviors of YAP are significantly eliminated after doping the impure Tm³⁺ ions, as evidenced by the minor energy gap of about 0.4 eV, which is close to the band gap energy of a 2 μm emitter source. On the basis of our developed crystal-field theory method, the 4f¹² electronic structures and energies of Tm³⁺ ions in the YAP crystal are calculated. The theoretical results indicate that the electric-dipole-induced transition ³H₄ → ³H₅ is mainly responsible for producing the light wave at approximately 2.3 μm. The present results provide an essential understanding of the rare-earth-ion-doped lasing materials and serve as a practical tool for further exploration of such materials.

Low-Cost Al2O3 Coating Layer As a Preformed SEI on Natural Graphite Powder To Improve Coulombic Efficiency and High-Rate Cycling Stability of Lithium-Ion Batteries

Coulombic efficiency especially in the first cycle, cycling stability, and high-rate performance are crucial factors for commercial Li-ion batteries (LIBs). To improve them, in this work, Al2O3-coated natural graphite powder was obtained through a low-cost and facile sol-gel method. Based on a comparison of various coated amounts, 0.5 mol % Al(NO3)3 (vs mole of graphite) could bring about a smooth Al2O3 coating layer with proper thickness, which could act as a preformed solid electrolyte interface (SEI) to reduce the regeneration of SEI and lithium-ions consumption during subsequent cycling. Furthermore, we examined the advantages of Al2O3 coating by relating energy levels in LIBs using density functional theory calculations. Owing to its proper bandgap and lithium-ion conduction ability, the coating layer performs the same function as a SEI does, preventing an electron from getting to the outer electrode surface and allowing lithium-ion transport. Therefore, as a preformed SEI, the Al2O3 coating layer reduces extra cathode consumption observed in commercial LIBs.

Re-Optimized Energy Levels and Ritz Wavelengths of (198)Hg I

The procedure of level optimization for the (198)Hg I spectrum emitted by electrodeless discharge lamps is revisited. Wavelength-measurement uncertainties and systematic shifts caused by interactions with the buffer gas and by calibration procedures are carefully analyzed and accounted for. Based on this extended analysis of the original measurements, the energy levels are re-optimized, which results in an improved set of level values consistent with the revised measured wavelengths. The newly obtained reliable Ritz wavelengths can be used as secondary wavelength standards in the wide range from 1200 Å to 65 000 Å.

Secondary γ Transitions in (159) Gd After Neutron Capture at Isolated Resonances

The (158)Gd(n,γ)(159)Gd reaction was studied at 12 isolated neutron resonances by the TOF method at the IBR-30 Fast Pulse Reactor at JINR Dubna. Totally 15 secondary γ transitions in (159)Gd were recorded in the range from 450 keV to 750 keV. Of these, six previously unseen transitions were placed on the established (159)Gd level scheme. The depopulation of strongly populated levels at 507.7 keV and 558.2 keV (the head and the first excited members of band 1/2(-) [521]) was observed for the first time. It was shown that the observed 507.7 keV γ line, masked by the annihilation peak, originates from an unresolved doublet of transitions from the 507.7 keV level to the ground state and from the 558.2 keV level to the level at 50.7 keV. The 507.7 keV level decays exclusively to the ground state, while the 558.2 keV level decays via two transitions with a branching ratio that agrees well with the prediction according to Alaga's rule.

Improved Wavelengths and Energy Levels of Doubly-Ionized Argon (Ar III)

New measurements of Ar III wavelengths between 508 Å and 4183 Å are combined with measurements from the literature to find improved values for the energy of most of the known levels in Ar III. Parameters derived from fitting the new level energies to an LS-coupling model are presented along with eigenvector compositions of the levels. On the basis of this analysis new designations are recommended for several levels.

Analysis of the (5d2+5d6s)-5d6p Transition Arrays of Os VII and Ir VIII, and the 6s 2S-6p 2P Transitions of Ir IX

The spectra of osmium and iridium were photographed in the 300 Å to 1600 Å region on a 3 m normal incidence spectrograph using a triggered spark source. The (5d² + 5d6s)-5d6p transition arrays of Os VII and Ir VIII were analyzed. All levels of these three configurations in both spectra have been established. There are 77 lines in Os VII and 71 lines in Ir VIII classified. The parametric least squares fitting calculations are used to interpret both spectra. The 6s²S_1/2-6p²P_1/2,3/2 transitions in Ir IX have also been identified.

Wavelengths and Energy Levels of Neutral Kr84 and Level Shifts in All Kr Even Isotopes

Interferometrically-measured wavelengths of 109 lines of neutral Kr⁸⁴ are compared with those of Kr⁸⁶. Sixty energy levels of neutral Kr⁸⁴ derived from those wavelengths and 25 Kr⁸⁶-Kr⁸⁴ isotope shifts previously measured are given along with their shifts from the energy levels of Kr⁸⁶. Twenty levels of each of Kr⁸², Kr⁸⁰, and Kr⁷⁸ are also evaluated using isotope-shift information in the literature. The differences between the experimentally observed shifts and the normal mass shift leave large negative residuals which are accounted for by ionization energy differences and by the specific mass shift. It appears that the volume effect causes only a very small, if any, energy level shift.

Energy Levels of Singly-Ionized Platinum

The analysis of Pt II is extended by using accurate wavelength measurements by Sansonetti et al. Forty-three new even and 104 new odd levels have been found. The Slater-Condon parametric method is used for the interpretation of the 5d⁹, 5d⁸6s, and 5d⁷6s² low even configurations and the 5d⁸(7s+6d) high even configurations with root mean square deviations smaller than 80 cm^-1. The importance of the 5d⁸-5d⁷6s core interaction in interpreting the even-parity levels is stressed.

Energy Levels of Neutral Platinum

All known energy levels of neutral platinum (Pt I) are presented, including 119 new levels based on analysis of recent comprehensive observations of the spectrum. These results are taken from a detailed analysis of the spectrum to be published in Journal de Physique II.

Analysis of the Spectrum of Doubly Ionized Molybdenum (Mo III)

The spectrum of doubly ionized molybdenum (Mo III) was produced in a sliding spark discharge and recorded photographically on the NIST 10.7-m normal incidence spectrograph in the 800-3250 Å spectral region. The analysis has led to the establishment of 76 levels of the interacting 4d⁴, 4d³ 5s and 4d² 5s² even configurations, 73 levels of the interacting 4d³ 5d and 4d³ 6s even configurations, and 181 levels of the interacting 4d³ 5p and 4d² 5s5p odd configurations. Approximately 3100 lines have been classified as transitions between these experimentally determined levels. Comparison between the observed levels and those calculated from matrix diagonalizations with least-squares fitted parameters shows standard deviations of 44, 33, and 183 cm^-1, respectively, for the levels of the three sets of configurations.

The Spectrum of Doubly Ionized Tungsten (W III)

The spectrum of doubly ionized tungsten (W III) was produced in a sliding-spark discharge and recorded photographically on the NIST 10.7-m normal-incidence vacuum spectrograph in the 600-2680 Å spectral region. The analysis has led to the establishment of 71 levels of the interacting 5d4, 5d3 6s and 5d2 6s2 even configurations and 164 levels of the interacting 5d3 6p and 5d2 6s 6p odd ones. A total of 2636 lines have been classified as transitions between the 235 experimentally determined levels. Comparison between the observed levels and those calculated from matrix diagonalizations with least-squares fitted parameters shows an rms deviation of ±87 cm-1 for the even configurations and ±450 cm-1 for the odd ones.

Revised Lifetimes of Energy Levels in Neutral Iron

Mean radiative lifetimes for 408 energy levels of neutral iron are revised from our 1967 paper on the basis of comparison with 81 subsequently measured lifetimes. The standard deviation of the ratio of the revised values to the reference lifetimes is 30 percent.

Wavelengths and Energy Levels of the Second Spectrum of Cerium (Ce ii)

The second spectrum of cerium (Ce ii) has been compiled in the wavelength region between 2500 Å and 24 000 Å. Of the 11 000 lines in the list, about 7500 are now classified as transitions between 192 odd levels and 288 even levels. The odd levels arise from 5 configurations (4f5d 2, 4f5d6s, 4f6s 2, 4f 26p, and 4f 3) and the even levels from 7 configurations (4f 26s, 4f 25d, 4f5d6p, 4f6s6p, 5d 3, 5d 26s, and 5d6s 2). The known levels extend up to only 52 000 cm-1 although the ionization potential is known to be 35 000 cm-1 higher.

A Theoretical Investigation of the Configurations (3d + 4s)8 4p in Neutral Cobalt (Co I)

Experimental levels of the configurations (3d + 4s)8 4p were compared with corresponding calculated values. On fitting 154 levels by means of 19 free parameters an rms error of only 164 cm-1 was obtained.

A Theoretical Investigation of the Configurations (3d + 4s)74p in Neutral Iron

Experimental levels of the configurations (3d + 4s)74p were compared with corresponding calculated values. On fitting 248 experimental levels by means of 20 free parameters an rms error of 213 cm-1 was obtained. It was shown that the correction parameters β and T were not significant.

Calculations of Znii 3d94s5s and Agi 4d95s6s, and Some New Levels in these Spectra

Results of intermediate-coupling calculations are given for Zn ii 3d 94s5s and Ag i 4d 95s6s. A [(4d 9)J i, (5s6s)J ii]J coupling scheme is appropriate for the latter. New 3d 94s(3D)5s 2D2½ and 3d 94s(1D)5s 2D2½ levels were found in Zn ii, and a few other additions and revisions are given for the analysis. The combinations of the new levels 3d 9(2D)4s4p(3P°)4 F 4 1 / 2 ° in Zn ii and 4d 9(2D)5s5p(3P°)2 F 2 1 / 2 ° in Ag i are also listed.

Odd Configurations in Singly-Ionized Copper

Experimental levels of the configurations 3d 94p, 3d 95p, 3d 96p, 3d 84s4p, 3d 94f, and 3d 95f of Cu ii were compared with corresponding calculated values. The electrostatic interactions between the configuration 3d 84s4p and the configurations 3d 94p, 3d 95p, and 3d 96p were considered explicitly. It was shown that the configurations 3d 94f and 3d 95f of Cu ii do not interact strongly with other configurations.

The Configurations (3d + 4s)n 4p in Neutral Atoms of Calcium, Scandium, and Titanium

Experimental levels of the configurations (3d + 4s) n 4p for neutral atoms of calcium, scandium, and titanium were compared with corresponding calculated values. The rms errors in the calculated values for Ca i, Sc i and Ti i were 23, 126, and 261 cm-1, respectively.

Configurations 3d n 4p in Singly Ionized Atoms of the Iron Group

Experimental levels of the configuration 3dn 4p in the second spectra of the iron group were compared with corresponding calculated values. Besides the electrostatic and spin-orbit interactions the α, β and T corrections were considered in the individual and general treatments. The insertion of the parameters β and T improved the results by about 21 percent. The rms error on fitting 703 levels by means of 21 free interaction parameters was 231 cm-1. Altogether 912 energy levels were predicted.

Configurations 3d n 4p + 3d n-1 4s4p in Sc II, Ti II, and V II

Experimental levels of the configurations 3d n 4p + 3d n-14s4p for Sc ii, Ti ii, and V ii were compared with corresponding calculated values. Electrostatic, spin-orbit interactions, as well as the α, β and T corrections, whenever possible, were considered for 3d n 4p and 3d n-14s4p. The electrostatic interaction between the configurations 3d n 4p and 3d n-14s4p was included explicitly. The rms errors for Sc ii, Ti ii and V ii were 4.6, 75 and 66 cm-1, respectively.

Energy Levels and Classified Lines in the First Spectrum of Technetium (Tc i)

Progress in the classification of Tc i lines is reported. About 2200 of the known Tc i lines between 2154 and 8918 Å are now classified as transitions between 108 even and 147 odd energy levels. Tables of levels and classified lines are given.

The First Spectrum of Tungsten (W i)

The first spectrum of tungsten (W i) has been observed in the region between 2000 Å and 10500 Å. Of the 6800 spectral lines reported here, about 5500 have been classified as transitions between 91 even and 365 odd levels.

The Configurations 3d n 4p in Doubly Ionized Atoms of the Iron Group

Experimental levels of the configurations 3d ⁿ 4p in the third spectra of the iron group were compared with corresponding calculated values. Besides the electrostatic and spin-orbit interactions the αL(L + 1), βQ and T corrections were considered in the individual and general treatments. The insertion of the parameters β and T improved the results by about 25 percent. The root-mean-square (rms) error on fitting 581 experimental levels by means of 21 free interaction parameters was 138 cm^-1. Altogether 912 energy levels were predicted.

Lifetimes of Energy Levels in Neutral Iron

Mean radiative lifetimes for 408 energy levels of neutral iron are calculated from the known transition probabilities of 3288 lines of Fe i.

The Configurations 4d n + 4d n - 1 5s in Doubly-Ionized Atoms of the Palladium Group

Four hundred and eighty-three energy levels belonging to the low even configurations of the third spectra of the palladium group are predicted by the use of interpolation formulas for the interaction parameters.