Search Results (11,562)

Cu₂ZnSn(S,Se)₄ (CZTSSe) is a candidate thin-film photovoltaic material; however, its performance is restricted by innate defect-induced nonradiative recombination. Low-concentration Ge doping has been identified as an efficient way to mitigate these defects, but the selenization temperature remains an important process parameter that governs the structure and optoelectronic characteristics of CZTSSe absorbers. In the present work, low-concentration Ge-doped Cu₂ZnSn_0.95Ge_0.05S₄ (CZTGS) precursor films were synthesized through a green, n-butylammonium butyrate-based solution approach. The effects of the selenization temperature (530–570 °C) on the microstructure, composition, and photovoltaic performance of Cu₂ZnSn_0.95Ge_0.05(S,Se)₄ (CZTGSSe) films and devices were comprehensively investigated. X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectrometer (EDS), atomic force microscopy (AFM) were performed to comprehensively characterize the synthesized samples, and the results suggested that the selenization temperature dramatically altered the film grain growth, crystallinity, elemental retention and surface roughness. Specifically, the film that underwent selenization at 550 °C presented the best crystallinity, which was accompanied by large-scale even grains, efficient Ge⁴⁺ addition to the kesterite lattice and the lowest surface roughness. These better properties in terms of structure and composition resulted in the lowest carrier transport resistance (R_s = 8.6 Ω∙cm²), improved recombination resistance (R_j = 5.9 kΩ∙cm²), inhibited nonradiative recombination, and prolonged carrier lifetime (τ_EIS = 35.8 μs). Therefore, the resulting CZTGSSe thin-film solar cell had an 8.69% better power conversion efficiency (PCE), while its open-circuit voltage (V_OC) was 0.42 V, the fill factor (FF) was 55.51%, and the short-circuit current density (J_SC) was 37.71 mA·cm^–2. Our results elucidate the mechanism by which the selenization temperature regulates low-concentration Ge-doped kesterite devices and provide more insights into the optimization of processes for cost-effective, high-performance, and green thin-film solar cells. Full article

This study reports the synthesis and evaluation of diclofenac-derived organotin(IV) complexes as photostabilizing additives for poly(vinyl chloride) (PVC). Diclofenac was selected as a ligand due to its aromatic structure and heteroatom-rich framework, enabling the formation of stable tin-based complexes with potential UV-absorbing and radical-scavenging properties. The synthesized di- and tri-organotin complexes were incorporated into PVC films at 0.5 wt.% and exposed to UV irradiation (365 nm) for up to 300 h to assess their stabilizing efficiency. Photodegradation was monitored by tracking changes in carbonyl, polyene, and hydroxyl indices, as well as weight loss and surface deterioration. Compared with blank PVC and ligand-containing films, the organotin-modified samples exhibited significantly slower growth of degradation indices, reduced mass loss, and improved surface integrity after irradiation. Among the evaluated additives, the tributyltin complex demonstrated the highest photostabilizing performance, showing superior retention of chlorine content and lower surface roughness parameters. Overall, the results indicate that diclofenac-based organotin(IV) complexes are effective photostabilizers for PVC, with the tributyltin derivative emerging as the most promising candidate for enhancing the durability of PVC materials under UV exposure. Full article

This study aims to develop and characterize novel dermatocosmetic formulations designed to hydrate the skin, improve its appearance, reduce wrinkles, and provide antioxidant, anti-ageing, antimicrobial, and anti-inflammatory benefits, along with potential protection against UVA and UVB radiation. The formulations contain the following ingredients: xanthan gum (0.5%), Calendula officinalis oil (5%), Argania spinosa oil (5%), Helianthus annuus oil (5%), liposomes containing a hydroalcoholic extract of pomace from local red or white grapes (2%), an olive oil-based emulsifier (6%), vitamin E (0.5%), cetearyl alcohol (3%), propylene glycol (8%), and purified water (up to 100%). The natural ingredients used in these formulations, i.e., the red or white grape pomace extract from the aforementioned Romanian varieties, the oils of Calendula officinalis, Argania spinosa, and Helianthus annuus, xanthan gum, and the olive oil-based emulsifier (Olliva), promote the concept of ‘green cosmetics’. The use of liposomes to deliver bioactive substances from hydroalcoholic extracts allows the gradual release of active ingredients into the skin. An alternative for incorporating grape pomace extract into a cream-type matrix involves the use of liposomes. Liposomes loaded with red or white grape pomace extract were prepared using the thin-film hydration technique, followed by ultrasonication and extrusion. The obtained formulations were characterized using bio-physico-chemical analysis procedures in terms of consistency, colour, homogeneity, aroma, pH, stretch, texture, stability, and antioxidant activity/free radical scavenging capacity, as well as in vitro polyphenol release behaviour. These newly developed dermatocosmetic formulations were the subject of a patent application in Romania. Full article

Hypochlorous acid (HClO) is widely used as a low-cost and effective disinfectant; however, its instability under heat and light necessitates simple and reliable monitoring methods. Herein, we report a morphology-evolving thin-film colorimetric sensor that enables intuitive visual detection of HClO through simultaneous color and pattern transitions. The sensor integrates two polymer films with distinct charge-state response behaviors, patterned in X-shaped and circular geometries on a single substrate. Upon exposure to HClO, chlorine-induced modification of amide and amine groups alters the surface charge states, thereby switching the adsorption preference for anionic and cationic dyes. This mechanism results in a pronounced transformation from a blue X-shaped motif to a red circular pattern, enabling direct visual discrimination between different HClO concentrations. Quantitative analysis of RGB values confirmed semi-quantitative detection in the sub-millimolar to millimolar range. The sensor exhibited a linear response in the range of 0–3 mM (R² > 0.979) with a limit of detection of 0.103 mM. The sensor further demonstrated practical applicability by tracking photodecomposition of a commercial disinfectant. This work demonstrates pattern-coupled colorimetric sensing as a straightforward, user-friendly approach for HClO monitoring. Full article

The control of oxygen stoichiometry via topochemical reduction offers a powerful route to manipulate the functional properties of complex oxides. Here, we investigate the chemical and structural evolution of epitaxial BiFeO₃ (BFO) thin films under CaH₂ treatment in a sealed tube, using a representative reduction condition of 365 °C for 2 h and a temperature window of 345 to 380 °C to probe the reduction dependent evolution. The inherent sensitivity of BFO’s multiferroic properties to oxygen vacancy formation and cation valence states makes it an ideal platform to probe reduction pathways. The aim of this work is to elucidate the detailed reduction pathway, including phase stability, valence changes in Bi and Fe, and the morphological consequences of oxygen extraction. Using a combination of spectroscopic, diffraction, and microscopic techniques, it was demonstrated that CaH₂ annealing does not yield a homogeneous oxygen-deficient perovskite. Instead, it triggers a decomposition into Bi₂O₃, metallic Bi, and FeO_x secondary phases, accompanied by severe surface roughening. This chemical reconstruction leads to a strong suppression of the ferromagnetic-like response and a redshift in the optical absorption edge. Full article

To address the lack of suitable glass systems for silicon nitride (Si₃N₄) surface metallization, which requires high wettability and thermal stability, and robust bonding between the copper layer and the ceramic substrate, a novel Bi₂O₃-TeO₂-B₂O₃-CuO glass system was developed. This study systematically investigated the influence of Bi₂O₃ concentration, glass properties, optimized paste composition, and brazing mechanism using phase analysis, microstructural characterization, particle size statistics, thermal analysis, and tensile testing. An optimal glass composition containing 20 mol% Bi₂O₃ was identified, exhibiting high thermal stability (ΔT = 224 °C) and a coefficient of thermal expansion of 9.63 × 10⁻⁶ °C⁻¹. At a brazing temperature of 750 °C, the glass demonstrated excellent wettability with a contact angle of 27°. A conductive paste comprising 94 wt% Cu and 6 wt% glass yielded a thick film with a minimum resistivity of 6.25 μΩ·cm and a maximum tensile strength of 25.2 MPa. Mechanism analysis revealed that the superior wettability drives the liquid glass phase to form a thin intermediate layer that significantly reinforces adhesion. These findings contribute to the research and development of subsequent novel glass systems with superior performance. Full article

We present a temperature-dependent photoluminescence (PL) study of solution-grown CsPbBr₃ bulk crystal and thin film, using one-photon and two-photon excitations. Twin planes are observed in X-ray diffraction spectra in crystal. In analyzing PL peak position and spectral widths as function of temperature, we find that the electron–phonon interaction is generally stronger in CsPbBr₃ crystals than in films. Moreover, with one photon excitation, emissions from excitons and trapped excitons are observed in CsPbBr₃ crystal. Under two-photon excitation, only the emissions from trapped excitons are observed in bulk crystal. Our work demonstrates that two-photon excitation PL is more sensitive to the trapped excitons inside CsPbBr₃, implicating an optical method to probe the inside quality of the crystal. Full article

Bismuth ferrite (BiFeO₃) is a promising material for developing the next generation of multifunctional electronic devices. However, the production of high-quality BiFeO₃ thin films is compromised by the tendency for structural and electronic defects to form during synthesis, which degrades their functional properties. In this work, BiFeO₃ thin films were prepared by chemical solution deposition to determine optimal conditions for minimizing oxygen vacancies and to evaluate the impact of these point defects on their physical properties. The films were pyrolyzed at 300 °C for 60 min and 360 °C for 10 min, and crystallized in air and in an O₂ atmosphere, at 600 °C and 640 °C for 40 min. High oxygen vacancies were observed in films prepared at low pyrolysis temperatures and crystallized in air, whereas oxygen vacancies were minimized in the film pyrolyzed and crystallized at high temperatures in an O₂ atmosphere. The oxygen vacancies markedly affected the films’ physical properties, leading to increased dielectric loss, dielectric dispersion, dc conductivity, and leakage current, with consequent degradation of photovoltaic and magnetic performance. These findings highlight the critical importance of controlling synthesis parameters to suppress oxygen vacancy formation and achieve high-quality BiFeO₃ thin films. Full article

This study explores the effects of sputtering pressure and power on FeCoNi high-entropy alloy films prepared by DC magnetron sputtering, focusing on microstructure, surface morphology, and static/high-frequency magnetic properties. In situ Lorentz TEM (LZ-TEM) was used to directly observe magnetic domain evolution. Results show that low sputtering pressure (1 mTorr) promotes strong FCC (111) crystallization, and smooth and dense surfaces. Increasing pressure leads to amorphization, higher roughness, and degraded magnetic performance. Under optimized pressure, 100 W sputtering power yields the best crystallinity, the smoothest surface, and optimal soft magnetic properties, including high remanence ratio, low coercivity, and clear ferromagnetic resonance in the 2–7.5 GHz range. The optimal parameters are confirmed as 1 mTorr and 100 W, producing uniform nanocrystalline FeCoNi films. In situ LZ-TEM reveals river-like domain walls, vortex–antivortex structures, and uniform magnetic moment precession, indicating weak domain pinning and excellent high-frequency magnetization consistency. This study provides experimental and theoretical support for the controllable fabrication of high-performance FeCoNi soft magnetic films for high-frequency devices. Full article

In this work, Fe, Co, Ni, Cu, and Mo powders were used as starting materials to prepare high-entropy alloy (HEA) thin films by a coating and vacuum sintering process. Using the HEA thin film as the substrate, selenium was subsequently deposited by chemical vapor deposition (CVD) to obtain high-entropy alloy selenide thin films (HEASe). The phase structure, surface chemical states, morphology, and elemental distribution of the porous films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The electrocatalytic hydrogen evolution performance of the electrodes was evaluated using a three-electrode configuration in 0.5 M H₂SO₄, 1 M KOH, 1 M KOH + 0.5 M NaCl, and 1 M KOH + 0.5 M Na₂S solutions. The results indicate that the HEA selenide thin-film electrodes exhibit favorable electrocatalytic behavior in all four electrolytes. Among them, HEASe-450 shows the best overall performance. In 0.5 M H₂SO₄, it requires an overpotential of only 57.6 mV to reach a current density of 10 mA cm⁻², with a Tafel slope of 146.96 mV dec⁻¹. In 1 M KOH, the overpotential at 10 mA cm⁻² is 50.1 mV, and the corresponding Tafel slope is 142 mV dec⁻¹. In 1 M KOH + 0.5 M NaCl, the overpotential is 52.7 mV with a Tafel slope of 122.72 mV dec⁻¹. In 1 M KOH + 0.5 M Na₂S, an overpotential of 85 mV is required, and the Tafel slope increases to 236 mV dec⁻¹. Full article

We investigated the dynamics of molecular reorientation in freely suspended smectic liquid–crystal films (FSLCFs) under the influence of heat flux. We also examined how external thermal gradients affect molecular alignment in these ultra-thin films. FSLCFs were fabricated in a temperature-controlled chamber in this study. When heat flux was applied perpendicular to the film plane, rotation of line defects, known as 2π walls, was observed. This rotation resulted from thermomechanical torque acting on the molecular director, a phenomenon referred to as the Lehmann effect. By analyzing the changes in defect evolution, how heat flux drives the self-organization of liquid–crystal structures can be understood. In this study, we combined experimental observations and computational simulations to model and interpret the results. The results enhance the understanding of the underlying mechanisms governing molecular reorientation and defect dynamics in FSLCFs, particularly in non-equilibrium conditions, to study this mechanism in the microgravity environment. The results also contribute to the development of advanced liquid–crystal technologies, with potential applications in energy-efficient devices, adaptive materials, and space technology systems. Full article

In this work, we demonstrate a functional and previously insufficiently explored route for converting cyclic olefin copolymer (COC) TOPAS^® thin films into antibacterial hybrid materials through a combination of solvent casting, plasma activation, noble-metal sputtering, and subsequent thermal or laser treatment. While COC is already well-known as a transparent, chemically resistant material for pharmaceutical and optical applications, its coupling with post-treated noble-metal nanostructures for antibacterial functionality has not been systematically described. The main contribution of this study lies in showing that COC can serve not only as a passive packaging substrate, but also as an active platform for the formation of biologically relevant surface nanostructures. Compared with previously reported metal/polymer systems, the present work provides clear evidence that noble-metal layers on COC undergo substantial structural evolution after thermal and excimer-laser treatment, resulting in regular nanoclustered morphologies. A particularly important finding is the detection of Au particle implantation below the COC surface during sputtering, as revealed by Rutherford backscattering spectrometry, which distinguishes this system from conventional surface-only metal coatings. Furthermore, we show that laser and thermal processing do not merely reshape the deposited layer, but significantly influence the final biological response of the material. Ag-based structures showed strong bactericidal behavior against both Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. The prepared samples were comprehensively characterized by AFM, DSC, RBS, SEM, and TGA, and their roughness and wettability were also evaluated, enabling direct correlation between physicochemical changes and antibacterial performance. These results introduce a new strategy for upgrading conventionally used pharmaceutical COC materials into multifunctional surfaces with added antibacterial value. Full article

We propose a silicon carbide (3C-SiC) periodic grating structure based on quasi-bound states in the continuum (q-BICs), which is used to significantly enhance the second-order optical nonlinear effect, including second-harmonic generation (SHG) and sum-frequency generation (SFG). By introducing a four-segment sub-wavelength grating on the SiC thin film and tailor the dimension, the structure successfully excites two q-BIC modes with ultra-high Q factor (resonant wavelengths at 1713.2 nm and 1804.6 nm respectively), realizing enhanced localization and nonlinear interaction of the strong light field. The simulation results show that under oblique incidence, the structure significantly enhances SFG efficiency and exhibits strong robustness to variations in key structural parameters. In addition, the study also reveals the coexistence of forward and backward SHG, and resonant wavelength tuning can be achieved by adjusting the structure dimension. This work not only provides a new path to enhance the nonlinear conversion efficiency of SiC thin films and solve the problem of difficult phase matching, but also lays the theoretical and technical foundation for the development of compact, efficient and integrated SiC-based nonlinear photonic devices. Full article

The mineralogical composition, textural characteristics, and uranium occurrence of sandstone-hosted uranium ores significantly influence the leaching performance during in situ recovery. This study investigates ore samples from the Zhenyuan uranium deposit, China, utilizing SEM, EPMA, XRD, and XRF to characterize their texture and mineralogy. Combined with thin-section leaching tests, batch stirring experiments, and pressurized column leaching experiments, the leaching behavior of pitchblende, associated gangue minerals, and the whole rocks were evaluated. The results indicate that: Uranium mainly occurs as nano-spherical and film-like pitchblende distributed along the edges of detrital grains and Ti-oxides. Minor uranium is incorporated into Ti-oxides and dolomite lattices via isomorphic substitution or adsorbed by chlorite. Under CO₂ + O₂ leaching conditions, pitchblende was almost completely dissolved, while U-bearing Ti-oxides experienced slight corrosion. Dolomite underwent partial dissolution, providing bicarbonate ions and improving rock permeability. Pyrite dissolution was limited during the early stage of leaching. The high dolomite content, low clay abundance, favorable pore structure, and easily leachable pitchblende suggest that the Zhenyuan deposit is well suited for CO₂ + O₂ in situ recovery. Increasing CO₂ pressure is recommended to enhance dolomite dissolution and improve uranium recovery efficiency. Full article

Over the past two decades, organic semiconductors have attracted significant research interest due to their advantageous features, including low-cost fabrication, lightweight properties, and portability, for photonic device applications. In this study, nickel sulfide doped with cobalt $(\mathrm{N}\mathrm{i}\mathrm{S}/\mathrm{C}\mathrm{o})$ nanocomposites were successfully synthesized via a wet-chemical processing technique and used as a dopant in the active layer of thin-film organic solar cells (TFOSCs). The poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PC61BM) blend was used as the active layer in this investigation. The devices were fabricated with $\mathrm{N}\mathrm{i}\mathrm{S}/\mathrm{C}\mathrm{o}$ nanocomposites at 1 wt%, 2 wt%, and 3 wt% in the active layer to determine the optimal dopant concentration. However, the experimental evidence clearly showed that the solar cell’s performance depends on the concentration of the $\mathrm{N}\mathrm{i}\mathrm{S}/\mathrm{C}\mathrm{o}$ nanocomposites. As a result, the highest power conversion efficiency (PCE) recorded in this experimental work was 6.11% at a 1% doping concentration, compared with 2.48% for the pristine reference device under AM 1.5G illumination (100 mW/cm²) in ambient conditions. The optical and electrical properties of the active layers are found to be strongly influenced by the inclusion of $\mathrm{N}\mathrm{i}\mathrm{S}/\mathrm{C}\mathrm{o}$ nanocomposites in the medium. However, the device doped with 1 wt% $\mathrm{N}\mathrm{i}\mathrm{S}/\mathrm{C}\mathrm{o}$ nanocomposite exhibits the highest absorption intensity, consistent with the better performance observed in this study, which can be attributed to the localized surface plasmon resonance (LSPR) effect. The optical and morphological characteristics of the synthesized $\mathrm{N}\mathrm{i}\mathrm{S}/\mathrm{C}\mathrm{o}$ nanocomposites were comprehensively analyzed using high-resolution transmission electron microscopy (HRTEM), high-resolution scanning electron microscopy (HRSEM), and additional complementary techniques. Full article