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The effects of pre-annealing the stacked metallic precursor (Zn/Cu/Sn/Mo/glass) on the structural and morphological properties of the resultant Cu 2 ZnSnSe 4 (CZTSe) thin films and their device properties were investigated. The crystalline quality and morphology of the CZTSe thin films were enhanced by the pre-annealing treatment. The pre-annealed CZTSe solar cells showed an improved conversion efficiency η of 7.02% compared with those that were not pre-annealed (η=5.65%). This enhancement in solar cell performance was mainly attributed to an improvement in shunt resistance ( R sh ) from 80 to 150 Ω cm 2 , which resulted in improvements in open-circuit voltage and fill factor. [ABSTRACT FROM AUTHOR]

Ge-incorporated Cu 2 ZnSnSe 4 (CZTGSe) thin films were prepared, and their materials and device properties were examined. The CZTGSe thin films were prepared using a two-step process comprising co-evaporation of each element and a subsequent annealing step. Ge atoms were successfully incorporated into the Cu 2 ZnSnSe 4 thin films, and the band-gap ( E g ) of CZTGSe was controlled via the full Ge/(Sn+Ge) ratio range of 0–1. In addition, the annealing environment containing GeSe 2 led to CZTGSe thin films with flat surfaces, dense morphologies, and large grains comparable to their thickness. The highest efficiency achieved with the fabricated CZTGSe solar cells was 10.03%, with an open circuit voltage ( V OC ) of 0.54 V. The CZTGSe thin-film solar cells exhibited an improved V OC deficit ( E g / q − V OC , q : electron charge) of 0.647 V, which is comparable to that of high-efficiency Cu 2 ZnSn(S x Se 1− x ) 4 solar cells. [ABSTRACT FROM AUTHOR]

The dependences of electronic structure of CZTS x Se 1 − x (CZTSSe) layers synthesized by sulfurization and/or selenization of the vacuum-deposited metal precursors on the anion mixing ratio x = S/(S + Se) have been studied by in-situ ultraviolet and X-ray photoemission spectroscopies (UPS, XPS) and inverse photoemission spectroscopy (IPES). The band alignment at interfaces between the CdS buffer by the sequential evaporation and the CZTSSe ( x = 0.28 and 1.0) has also been investigated by the in-situ measurements of these spectroscopies. The UPS/IPES results of the CZTSSe surfaces have revealed linear expansion of band gap energy E g with an increase of x : E g (CZTSe; x = 0) = 0.9–1.0 eV and E g (CZTS; x = 1) = 1.5–1.6 eV. This expansion mainly originates in the rise of conduction band minimum CBM: CBM (CZTSe; x = 0) = 0.45–0.50 eV and CBM (CZTS; x = 1) = 0.95–1.05 eV. The in-situ measurements of the interface electronic structure have revealed that the CdS/CZTSSe ( x = 0.28) interface has a so-called “type I” band alignment with a conduction band offset CBO about + 0.2 eV which is favorable to high cell performance. A negative CBO was distinguished for the CdS/CZTS ( x = 1.0) interface, and the observed change in the band alignment with the anion mixing ratio was consistent with that of the variation in cell-performances. [ABSTRACT FROM AUTHOR]

Abstract: The relationship between the composition and conversion efficiency of Cu2ZnSnSe4 (CZTSe)-based solar cells was investigated. CZTSe films were grown by thermal deposition using a coevaporation method. It was found that the composition of CZTSe and Na concentration [Na] have strong correlations to the conversion efficiency, and higher-efficiency samples were obtained with the composition ratios closer to Zn/Sn~1.6, Cu/(Zn+Sn)~0.8, and [Na]~2%. The highest conversion efficiency (η =2.1%) was obtained in the composition region, and the composition was significantly nonstoichiometric. The CZTSe composition was automatically fixed on a tie line between Cu2ZnSnSe4 and ZnSe, and it was demonstrated that this composition can be expressed by one parameter. The structural and electrical properties of the high- and low-efficiency samples were also investigated. No significant differences in such properties were observed between the high- and low-efficiency samples by surface, x-ray diffraction, and Raman measurements. However, the low-efficiency sample showed a high carrier concentration. [Copyright &y& Elsevier]

Abstract: In this paper, we report a recent progress in Cu(In,Ga)Se2 (CIGS) solar cells and mini-modules demonstrated on soda-lime glass (SLG) substrates, which are one of the most common and cost effective substrate materials for chalcopyrite photovoltaics. CIGS absorber layers grown by the three-stage co-evaporation process was used with an optimized [Se]/[metal] flux ratio and preferable substrate temperatures for SLG substrate thicknesses. SLG substrates of 0.28–1.1mm in thickness, which are thinner than that generally used in laboratories and industries (∼2–3mm), were employed to develop techniques for further reductions of material cost and module weight. Solar cell and mini-module efficiencies of >19% and >17%, respectively, with relatively high open circuit voltages (V oc) and fill factors (FF) (V oc 0.77V and FF 0.79 for cells, and V oc 0.77V and FF 0.74 for mini-modules) were demonstrated using a composition ratio [Ga]/([In]+[Ga]) of 0.45 for the CIGS absorber layers. Key techniques and future directions toward highly efficient CIGS solar cells and modules with high values of V oc and FF are discussed. [Copyright &y& Elsevier]

Abstract: A fatty-acid Langmuir–Blodgett (LB) monolayer ionically adsorbed to the substrate has been prepared by adopting ZnO-based conductor and pure water respectively as the substrate and subphase. Ionization of the fatty-acid molecules has been detected by infrared reflection–absorption spectroscopy (IR-RAS), which is enabled by the condensed free electrons in the doped ZnO substrate. On the contrary, IR-RAS measurements have indicated that fatty-acid molecules transferred onto Au and indium-tin-oxide substrates from a pure-water surface are not ionized. In addition, it has been demonstrated that these ionically bonded fatty-acid monolayers protect the ZnO transparent electrode from chemical attack by NH3 gas. Since the LB technique is a simple method applicable to a wide variety of materials, the present results may lead to a new way of obtaining functional organic–inorganic nanosystems. [ABSTRACT FROM AUTHOR]

Abstract: Effectiveness of the infrared reflection–absorption spectroscopy (IR-RAS) using transparent electrodes made of Ga-doped ZnO as metal substrates has been demonstrated. For a merocyanine dye with and without a metallic cation, differences in the IR-RAS spectrum have been clearly observed, even when the quantity of the material is restricted to the monolayer level. Referring to the visible transmission spectra of the samples, which can be measured thanks to the transparency of the substrates, chelation of the metallic cation by the carboxyl group belonging to a dye molecule and the keto group belonging to an adjacent dye molecule has been regarded as a promising candidate for the J-aggregation driver. [Copyright &y& Elsevier]

Cu 2 Sn 1− x Ge x Se 3 (CTGSe) thin film solar cells were fabricated by coevaporation with post-annealing treatment. The CTGSe solar cells showed a remarkably improved conversion efficiency of 3.0% compared to a Cu 2 SnSe 3 (CTSe) solar cells ( η =0.045%). This enhancement of the solar cell properties is attributed to improvement of the film morphology (e.g., grain size and densification), reduction of the carrier concentration, and bandgap widening with Ge incorporation into the CTSe. The optical band gap of CGTSe ( x =0.58) is 0.77 eV, which is close to the 0.8 eV optimal bandgap of bottom cells in multi-junction solar cells. [ABSTRACT FROM AUTHOR]

In this article, we look, from the carrier perspective, at the effect of the double grading in a CIGS absorber, in order to understand its benefit compared to a single grading. We focus on the double grading effects on the conduction band edge, generation rate and carrier collection. We first show that, when the minimum bandgap position (notch position) is outside of the absorber depletion region, a local maximum of the conduction band edge appears at the back of the depletion region, creating a hump, which hinders the collection of electrons. Interpreting the effect of the grading as an effective electric field, we show that the hump is caused by the competition between the absorber internal electric field and the grading created effective electric field. From this, we deduce that the notch should be positioned in the depletion region. As expected, the generation rate increases significantly at the notch position. However, studying carrier collection and the recombination rate, we show that, even if in the ideal case we should observe a total collection of carriers generated in the depletion region, the recombination rate in the SCR increases significantly when the notch is in it. We propose that this is caused by the increased carrier generation close to recombination centres. The ideal notch position is, therefore, a compromise between being close enough to the front to have a maximal carrier collection and avoiding the creation of a hump, while minimizing the carrier recombination. • For high efficiency, the bandgap minimum must be close to the edge of the SCR. • A minimum bandgap outside the depletion region creates a hump at its back. • The competition between the internal and the notch electric field controls x hump. • A minimum bandgap in the depletion region increases recombination in it. • The best efficiency is reached when minimizing recombination for a notch in the SCR. [ABSTRACT FROM AUTHOR]

Abstract: We have developed a fabrication process for integrated submodules using Cu(In,Ga)Se2 (CIGS) absorbers deposited by in-line three-stage evaporation. An in-situ monitoring system for the compositions and thicknesses of the CIGS absorbers was also developed. High-performance CIGS submodules with efficiencies as high as η=15.8% with 17 interconnected cells (aperture area: 76.5cm2) have been fabricated. [ABSTRACT FROM AUTHOR]

Indium oxide based transparent conductive oxides (TCOs) are promising contact layers in solar cells due to their outstanding electrical and optical properties. However, when applied in Cu(In,Ga)Se 2 or Si-hetero-junction solar cells the specific roughness of the material beneath can affect the growth and the properties of the TCO. We investigated the electrical properties of hydrogen doped and hydrogen-tungsten co-doped indium oxides grown on rough Cu(In,Ga)Se 2 samples as well as on textured and planar glass. At sharp ridges and V-shaped valleys crack-shaped voids form inside the indium oxide films, which limit the effective electron mobility of the In 2 O 3 :H and In 2 O 3 :H,W thin films. This was found for films deposited by magnetron sputtering and reactive plasma deposition at several deposition parameters, before as well as after annealing and solid phase crystallization. This suggests universal behavior that will have a wide impact on solar cell devices. • Electron mobility of In 2 O 3 :H-based TCOs decreases with increased CIGS roughness. • Crystalline fraction after growth of In 2 O 3 :H-based TCOs affects electron mobility. • Crack-shaped void formation at sharp ridges and V-shaped valleys. • Introduction of a new parameter to describe CIGS topography more suitable. [ABSTRACT FROM AUTHOR]

Abstract: The quantum dynamics of Bi2Sr2CaCu2O8+δ intrinsic Josephson junctions (IJJ’s) is studied based on the escape rate measurements. The saturations observed in the escape temperature and the width of the switching current below 0.45K (=T ∗) indicate the transition of the switching mechanism from the thermal activation to the macroscopic quantum tunneling at T ∗. It is shown that most of the switching properties are consistently explained in terms of the underdamped Josephson junction with quality factor of about 70 in spite of possible damping due to d-wave superconductivity. The present result gives the upper limit of the dissipation of IJJ’s. [Copyright &y& Elsevier]

[Purpose] We aimed to examine factors at admission that are related to independence in stair climbing at discharge among patients with vertebral compression fractures. [Participants and Methods] The study included 179 female patients with vertebral compression fractures. A decision tree model was created to predict independence in stair climbing at discharge based on Dementia Scale-Revised, skeletal muscle mass index body mass index, grip strength, number of vertebral fractures, and number of injuries at admission. [Results] Analysis with the decision tree model showed that skeletal muscle mass index at admission, age, and grip strength were predictors for independence in stair climbing at discharge. [Conclusion] Patients with vertebral compression fractures who have a low skeletal muscle mass index and grip strength on admission may require assistance with stair climbing upon discharge., Competing Interests: No potential conflict of interest was reported by the authors., (2024©by the Society of Physical Therapy Science. Published by IPEC Inc.)

[Purpose] We investigated the relationship of quality of life (QOL) with cognitive function, physical function, and activity ability, and aimed to identify functions related to QOL improvement, among elderly people who use day-care rehabilitation. [Participants and Methods] The participants were 37 elderly rehabilitation users, whose QOL was assessed using the Health Organization QOL26 (WHOQOL26), which consists of a 26-item self-report questionnaire. Cognitive function was assessed using the Mini-Mental State Examination, while physical function was assessed with seated forward bending, knee extension, grip, 30-second chair stand test, timed up and go test, and gait speed. Activity ability was assessed using the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG index). [Results] A positive correlation was found between five WHOQOL26 categories (psychological QOL, social QOL, environmental QOL, total QOL, and QOL average) and social role in the TMIG index. There was also a positive correlation between four WHOQOL26 categories (psychological QOL, social QOL, environmental QOL, and QOL average) and instrumental activity of daily living in the TMIG index. To identify factors influencing the QOL score, association with TMIG index was investigated. Social role in the TMIG index was a positive factor in psychological and social QOL. [Conclusion] Enhancing social role is important to improve QOL of elderly rehabilitation users., Competing Interests: The authors have no conflicts of interest directly relevant to the content of this article., (2023©by the Society of Physical Therapy Science. Published by IPEC Inc.)

[Purpose] This study compared the motor skills and cognitive functions of elderly participants who required support with those who did not require support. We aimed to evaluate the characteristics of impairment in sub-items of cognitive function in patients who needed support to predict future clinical issues. [Participants and Methods] We surveyed 31 participants requiring support under the day care service insurance system for which they attended day care service centers in Japan (rehabilitation users) and 10 healthy participants who attended a university for lifelong learning (healthy elders). Data on personal attributes of the participants were collected, and the Cardio-Ankle Vascular Index and motor and cognitive functions were assessed. [Results] Although the participants undergoing rehabilitation were, on average, 6 years older than the healthy elders, we found no significant differences between the two groups in closed-eye, one-legged standing, grip strength, or quadriceps muscle strength. In terms of the Tokyo Cognitive Assessment for mild cognitive impairment, we found no significant differences between those undergoing rehabilitation and healthy elders in clock drawing performance, serial 7 task performance, or orientation; however, there were significant differences in erase character, copy of triangular pyramid, composition, read of digits, go/no-go, word recall, story reproduction, ToCA total score. [Conclusion] We believe that it is imperative for day care service centers to conduct programs that maintain cognitive function in addition to programs for improvement of physical function., (2022©by the Society of Physical Therapy Science. Published by IPEC Inc.)

In this study, the influences of bromine-based etching (Br etching) of narrow band gap CuInSe 2 (CIS) absorbers and Cu(In,Ga)Se 2 absorbers with various single Ga gradings (CIS:Ga) on the properties of solar cells were investigated. Absorbers with narrow absorption edge energies ( E abs ) of 1.0-1.02 eV, ideal for the application as a bottom cell in a tandem device, were fabricated using a modified three-stage process and subjected to Br etching. The evolution of surface flatness and their optical and electrical properties upon Br etching were investigated. Br etching typically reduced the root-mean-square deviation of the surface roughness height ( R q ) for a CIS:Ga absorber from several hundreds to several tens of nanometers, whereas for some CIS absorbers, R q reduction was limited by the remaining voids. Moreover, Br etching reduced the leakage current across the pn junction. The high shunt resistances ( R sh ) typically up to >10 kΩ·cm 2 were obtained by introduction of Br etching. However, etching sometimes adversely increased the V OC deficit. The investigation of the minority carrier lifetime and diode parameters revealed that back-surface recombination in CIS and low-Ga CIS:Ga solar cells increased as the absorber layer thickness decreased. A higher Ga grading significantly reduced back-surface recombination. Narrow band gap CIGS solar cells with improved surface flatness and high V OC were achieved by introducing Br etching and proper Ga grading.

Photovoltaic devices based on Cu(In,Ga)Se 2 (CIGS) typically employ polycrystalline thin films as the absorber layer. This is because, to date, the highest conversion efficiencies have been attained with polycrystalline CIGS films. Recently, Nishinaga et al. presented an epitaxial CIGS thin-film solar cell grown on a GaAs (100) substrate with a conversion efficiency of 20.0%. In this contribution, we study the optical and structural properties of this high-efficiency epitaxial film, along with others with different compositions using cathodoluminescence spectrum imaging and transmission electron microscopy. A comparison of the high-efficiency epitaxial film and a traditional polycrystalline film with a similar global composition reveals significant differences in microstructure and uniformity of emission properties despite similar performance. The analysis of epitaxial films with a higher gallium concentration indicates that the emission characteristics and nature of extended defects in epitaxial CIGS films are strongly dependent on the gallium content. The results presented here provide evidence that, with further optimization, photovoltaic conversion efficiencies of epitaxial CIGS films could exceed those of polycrystalline CIGS.

The photovoltaic performance of Cu 2 ZnSnSe 4 (CZTSe) solar cells subjected to surface oxygen plasma treatments is investigated. The observed improvements are related to an enhancement of the open circuit voltage V OC , that is, the suppression of the V OC deficit. The V OC monotonically increases with treatment time up to 0.460 V. The origin of this improvement is discussed, and it is concluded that the effectiveness of the surface treatment is not due to oxygen-related alloying but instead to the homogeneous oxidation and removal of the oxidized CZTSe surface layer. The surface oxygen content increases with surface treatment time, although surface oxides are fully removed after ammonia treatment, which is conducted in a similar manner to CdS buffer deposition. The reduction of surface recombination is confirmed by time-resolved photoluminescence measurements, and the minority carrier lifetime deduced using the fast decay component increases with increasing treatment time. The relationship between photovoltaic properties and lifetime is clearly demonstrated. The best-performing CZTSe solar cell obtained using surface oxygen treatment demonstrates a conversion efficiency of 11.7%, which is higher than those of previous reports on CZTSe cells.

The surface electronic properties of the light absorber and band alignment at the p/n heterointerface are key issues for high-performance heterojunction solar cells. We investigated the band alignment of the heterointerface between cadmium sulfide (CdS) and Ge-incorporated Cu 2 ZnSnSe 4 (CZTGSe), with Ge/(Ge + Sn) ratios ( x) between 0 and 0.4, by X-ray photoelectron, ultraviolet, and inversed photoemission spectroscopies (XPS, UPS, and IPES, respectively). In particular, we used interface-induced band bending in order to determine the conduction band offset (CBO) and valence-band offset (VBO), which were calculated from the core-level shifts of each element in both the CdS overlayer and the CZTGSe bottom layer. Moreover, the surface electronic properties of CZTGSe were also investigated by laser-irradiated XPS. The CBO at the CdS/CZTGSe heterointerface decreased linearly, from +0.36 to +0.20 eV, as x was increased from 0 to 0.4; in contrast, the VBO at the CdS/CZTGSe heterointerface was independent of Ge content. Both UPS and IPES revealed that the Fermi level at the CZTGSe surface is located near the center of the band gap. The hole concentration at the CZTGSe surface was on the order of 10 11 cm -3 , which is much smaller than that of the bulk (∼10 16 cm -3 ). We discuss the differences in hole deficiencies near the surface and in the bulk on the basis of laser-irradiated XPS and conclude that hole deficiencies are due to defects distributed near the surface with densities that are lower than in the bulk, and the Fermi level is not pinned at the CZTGSe surface.

For the complete structure elucidation of an endogenous sperm-activating and -attracting factor isolated from eggs of the ascidian Ascidia sydneiensis ( Assydn-SAAF), its two possible diastereomers with respect to C-25 were synthesized. Starting from ergosterol, the characteristic steroid backbone was constructed by using an intramolecular pinacol coupling reaction and stereoselective reduction of a hydroxy ketone as key steps, and the side chain was introduced by Julia-Kocienski olefination. Comparison of the NMR data of the two diastereomers with those of the natural product led to the elucidation of the absolute configuration as 25 S; thus the complete structure was determined and the first synthesis of Assydn-SAAF was achieved.

We found that elemental Si-doped Cu(In,Ga)Se 2 (CIGS) polycrystalline thin films exhibit a distinctive morphology due to the formation of grain boundary layers several tens of nanometers thick. The use of Si-doped CIGS films as the photoabsorber layer in simplified structure buffer-free solar cell devices is found to be effective in enhancing energy conversion efficiency. The grain boundary layers formed in Si-doped CIGS films are expected to play an important role in passivating CIGS grain interfaces and improving carrier transport. The simplified structure solar cells, which nominally consist of only a CIGS photoabsorber layer and a front transparent and a back metal electrode layer, demonstrate practical application level solar cell efficiencies exceeding 15%. To date, the cell efficiencies demonstrated from this type of device have remained relatively low, with values of about 10%. Also, Si-doped CIGS solar cell devices exhibit similar properties to those of CIGS devices fabricated with post deposition alkali halide treatments such as KF or RbF, techniques known to boost CIGS device performance. The results obtained offer a new approach based on a new concept to control grain boundaries in polycrystalline CIGS and other polycrystalline chalcogenide materials for better device performance.

Amorphous (a-) In 2 O 3 -based front contact layers composed of transparent conducting oxide (TCO) and transparent oxide semiconductor (TOS) layers were proved to be effective in enhancing the short-circuit current density (J sc ) of Cu(In,Ga)Se 2 (CIGS) solar cells with a glass/Mo/CIGS/CdS/TOS/TCO structure, while maintaining high fill factor (FF) and open-circuit voltage (V oc ). An n-type a-In-Ga-Zn-O layer was introduced between the CdS and TCO layers. Unlike unintentionally doped ZnO broadly used as TOS layers in CIGS solar cells, the grain-boundary(GB)-free amorphous structure of the a-In-Ga-Zn-O layers allowed high electron mobility with superior control over the carrier density (N). High FF and V oc values were achieved in solar cells containing a-In-Ga-Zn-O layers with N values broadly ranging from 2 × 10 15 to 3 × 10 18 cm -3 . The decrease in FF and V oc produced by the electronic inhomogeneity of solar cells was mitigated by controlling the series resistance within the TOS layer of CIGS solar cells. In addition, a-In 2 O 3 :H and a-In-Zn-O layers exhibited higher electron mobilities than the ZnO:Al layers conventionally used as TCO layers in CIGS solar cells. The In 2 O 3 -based layers exhibited lower free carrier absorption while maintaining similar sheet resistance than ZnO:Al. The TCO and TOS materials and their combinations did not significantly change the V oc of the CIGS solar cells and the mini-modules.

Bafilomycin (Baf) is one of the most potent inhibitors of vacuolar-type ATPase, which is strongly implicated in age-related diseases. However, the binding site of the antibiotic on the protein remains unclear because of the complexity of the structure of Baf bound to the target subunit in the transmembrane region. For conducting structural studies by applying solid-state NMR, which is one of the most promising methodologies available for structural analysis in membrane system, preparing bioactive fluorinated Baf analogues is essential. In this study two Baf analogues were carefully designed and efficiently synthesized through the convergent coupling of three segments. Biological evaluation revealed that the activity of 24-F-Baf was comparable to that of Baf, indicating its utility as a potential probe for solid-state NMR analysis. By contrast, desmethylated 24-F-Baf exhibited markedly diminished activity. The absence of two methyl groups caused a critical conformational change in the macrocyclic core structure necessary for binding to the target protein., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)