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ZnO–TiO2 thin films containing 0.5 mol%, 1.0 mol%, and 5.0 mol% ZnO were synthesized by oxidative solid-phase pyrolysis. The materials contained anatase and rutile phases with particle size of 6–13 nm, as confirmed using X-ray phase analysis and scanning electron microscopy. When a certain number of ZnO crystallites appeared in the TiO2 film structure in the temperature range of room temperature to 220 °C, a two-level response of the film resistance was observed, differing by approximately 10%, as obtained by electrophysical measurements. The two-level response correlates with the formation of two donor energy levels of 0.28 and 0.33 eV in the band structure of the ZnO–TiO2 films. The donor level with a higher activation energy corresponded to the Ti vacancy (V−Ti), and that with a lower activation energy corresponded to the Zn vacancy (V−Zn). Two levels of gas-sensitive properties were noted for 0.5ZnO–TiO2, 1ZnO–TiO2, and 5ZnO–TiO2 under the influence of 50 ppm NO2 at 250 °C. Such two-level responses can be ascribed to the pinning of the Fermi level on ZnO and TiO2 nanocrystallites. The mechanism of the beak-shaped and two-level responses of sensors based on composite nanomaterials when exposed to various gases was elucidated.

This study introduces a novel approach for analyzing thin film interference spectra by employing a micro-spectrometer equipped with a spectral chip. Focusing on zinc oxide (ZnO) thin films prepared via the sol–gel method, this research aims to explore the films’ physical properties through spectral analysis. After obtaining the interference spectrum of the ZnO thin films, the peak positions within the spectrum were cataloged. Mathematical simulation was used to adjust the refractive index and thickness of the films to match the simulated interference peak positions with the observed peak positions. The thickness of the prepared ZnO film was estimated to be 4.9 μm and its refractive index at 80 °C was estimated to be 1.96. In addition, the measurement system was used to detect environmental changes, including temperature changes and gas exposure. It was observed that the optical characteristics of ZnO films exhibit marked variations with temperature shifts, enabling the establishment of a temperature calibration curve based on spectral feature displacement. In addition, experiments using a variety of gases showed that NO2 and gaseous isopropanol significantly affect the interference spectrum of ZnO, with the peak of the interference spectrum shifted by 2.3 nm and 5.2 nm, respectively, after injection of the two gases. This indicates that interferometric spectroscopy can serve as an effective tool for ZnO monitoring, capable of selectively detecting specific gases.

Collagen is one of the main constituents of mammalian extracellular matrix and is used extensively as a coating for tissue culture dishes and medical implants to promote cell growth and proliferation. By modulating the topography of the collagen coating at the nanometer to micrometer length scales, it is possible to achieve spatial control over cell growth and morphology. In this work, we are exploring the self-assembly of a thin collagen film on a glass substrate as a way to create new nanoscale surface features. By controlling the collagen concentration and adding an oscillatory flow, we are able to enrich the collagen film surface with a localized pattern of ripples oriented perpendicular to the flow direction. We propose that these ripples are the result of dewetting of the collagen film that leads to the formation of adjacent holes. We observe that individual holes form with an anisotropic rim due to the microstructure of the deposited collagen fibril network. This intrinsic anisotropy and the oscillatory flow yield new holes being formed in the film next to existing rims. As holes keep growing deeper, the rims extend along the flow direction, and the holes appear rectangular in shape, which gives the linear array of holes the apparent morphology of a ripple. Overall, we are able to create localized ripples at the surface of collagen films that would be difficult to produce via standard nanofabrication techniques.

Reasonable design of electrode material with low cost, lightweight, and excellent electrochemical properties is of great significance for future large-scale energy storage applications. Herein, we report the electrochemical and supercapacitive behaviour of the liquid redox of catocene, 2,2’-bis(ethyl-ferroceneyl) propane, self-assembled on a basal plane pyrolitic graphite electrode in comparison to the solid ferrocene thin film in aqueous sodium sulfate electrolyte. The modified electrode surfaces were evaluated to assess the iron content and the formation of thin film using scanning electron microscopy, laser-induced breakdown spectroscopy, and attenuated total reflectance method. Also, the supercapacitive performances of the related modified electrodes were assessed and compared using cyclic voltammetry and galvanostatic charge-discharge in a three-electrode system and an asymmetric two-electrode supercapacitor system. Electro­chemical results showed that the electrode processes are diffusion-controlled with battery-like behaviour, and the liquid catocene exhibits more effective interaction with the graphite surface in comparison to solid ferrocene. The catocene surface coverage on graphite is nearly 50-75 % higher than ferrocene, leading to improved interaction and charge transfer resistance, observed in electrochemical impedance spectroscopy studies. In galvanostatic charge-discharge evaluations, the supercapacitor based on catocene modified electrode shows a specific capacitance of 141.2 F g-1 at a current density of 1.0 A g-1, with a specific energy density of 56.7 Wh kg-1 at a power density of 2.9 kW kg-1.

The effect of varying Al concentrations on the electrochemical corrosion resistance of binary Mg-Al solid solutions thin films under alkaline immersion conditions was investigated via a combination of in-situ flow-cell, scanning vibrating electrode technique and microscopy analysis. These spatially resolving characterization techniques are employed along the Al concentration gradient of the combinatorically grown thin films enabling efficient screening of the Al concentration dependent electrochemical corrosion behaviour. The analysis revealed an increasing corrosion resistance with increasing Al concentration, as a consequence of Al induced hydroxide reinforcement. Specifically, the addition of >4 wt.% Al decreases the corrosion current density in the range of 70–90 % compared to pure Mg.

The present work reports the design, synthesis, and sensing applications of Diamino bis-benzimidazoquinoline (DA-BISQ) derivatives. These compounds were synthesized in appreciable yield and characterized by FT-IR, 1H, and 13C NMR spectral and mass spectrometry. Optical studies revealed intriguing dual excitation properties: single excitations at λex 330-386 nm and double excitations at λex 660-772 nm in 10 % ethanol-water medium. The near-infrared excitation region λex 660-772 nm was particularly focused on the detection of F¯, Cl¯, Br¯, I¯, AcO ̄, ClO4¯, NO3¯, and HPO4¯ anions. Notably, selective fluorescence quenching ''OFF'' responses were observed for geometric anions like AcO¯, ClO4¯, NO3¯, and HPO4¯. Interestingly, the pyridine spacer-containing derivative 1c exhibited a unique fluorescence ''OFF-ON'' response for the phosphate ion. Cyclic voltammetry titration further corroborated the binding affinity towards phosphate. To demonstrate practical applicability, a thin-film strip of receptor 1c was fabricated and tested for effective phosphate sensing in human blood serum samples. Density functional theory calculations were performed to elucidate the sensing mechanism with the phosphate anion. The combined experimental and theoretical results suggest an internal charge transfer process between the receptor and the anion.

Significant advances in the field of energy storage have enabled scientists to explore highly stable electro-active electrodes for high-performance supercapacitors. The present investigation describes the synthesis of well-ordered NiMoO4 nanowalls at 140 °C using hydrothermal synthesis, which was then grown directly on Ni foam with different reaction times. The resulting NiMoO4 nanowalls were utilized as electro-active electrodes for electrochemical supercapacitor applications. The reaction time was found to be a critical factor in achieving the ordered NiMoO4 nanowalls on the Ni foam, and at a reaction time of 12 h, the nanosheets self-organized into a nanowall-like morphology over the Ni foam. Pure NiMoO4 crystal phases with less surface imperfections were produced by the 12-hour reaction time, as demonstrated by the compositional, structural, and crystalline characteristics. As an electro-active electrode, the NiMoO4 electrode with a 12-hour reaction time showed the highest specific capacitance of 357.6 Fg−1 at 0.01 Vs−1 compared to NiMoO4 electrodes with reaction times of 6h (53.06 Fg-1 at 0.01 Vs−1) and 20h (55.4 Fg-1 at 0.01 Vs−1). The NiMoO4 electrode also demonstrated exceptional stability in an alkaline electrolyte, exhibiting less deterioration in multicycles CV after 100 repeated cycles. The excellent electrochemical properties of the NiMoO4 electrode are attributed to its unique ordered nanowall structure, which improves surface area and electrical conduction, accelerating fast redox reactions. These properties make it a promising material for use in pseudocapacitors, with implications for high-performance energy storage solutions in industrial sectors.

Aramid copolymers have garnered significant interest due to their potential applications in extreme environments such as the aerospace, defense, and automotive industries. Recent developments in aramid copolymers have moved beyond their traditional use in high-strength, high-temperature resistant fibers. There is now a demand for new polymers that can easily be processed into thin films for applications such as electrical insulation films and membranes, utilizing the inherent properties of aramid copolymers. In this work, we demonstrate two novel aramid copolymers that are capable of polymerizing in polar organic solvents with a high degree of polymerization, achieved by incorporating flexible bis(4-aminophenoxy) benzene moieties into the chain backbone. The synthesized MBAB-aramid and PBAB-aramid have enabled the fabrication of exceptionally thin, clear films, with an average molecular weight exceeding 150 kDa and a thickness ranging from 3 to 10 μm. The dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) reveal that the thin films of MBAB-aramid and PBAB-aramid exhibited glass transition temperatures of 270.1 °C and 292.7 °C, respectively, and thermal decomposition temperatures of 449.6 °C and 465.5 °C, respectively. The mechanical tensile analysis of the 5 μm thick films confirmed that the tensile strengths, with elongation at break, are 107.1 MPa (50.7%) for MBAB-aramid and 113.5 MPa (58.4%) for PBAB-aramid, respectively. The thermal and mechanical properties consistently differ between the two polymers, which is attributed to variations in the linearity of the polymer structures and the resulting differences in the density of intermolecular hydrogen bonding and pi-pi interactions. The resulting high-strength, ultra-thin aramid materials offer numerous potential applications in thin films, membranes, and functional coatings across various industries.

We report the pulsed laser deposition (PLD) of nanocrystalline/amorphous homo-composite BaTiO3 (BTO) films exhibiting an unprecedented combination of a colossal dielectric constant (εr) and extremely low dielectric loss (tan δ). By varying the substrate deposition temperature (Td) over a wide range (300–800 °C), we identified Td = 550 °C as the optimal temperature for growing BTO films with an εr as high as ~3060 and a tan δ as low as 0.04 (at 20 kHz). High-resolution transmission electron microscopy revealed that the PLD-BTO films consist of BTO nanocrystals (~20–30 nm size) embedded within an otherwise amorphous BTO matrix. The impressive dielectric behavior is attributed to the combination of highly crystallized small BTO nanograins, which amplify interfacial polarization, and the surrounding amorphous matrix, which effectively isolates the nanograins from charge carrier transport. Our findings could facilitate the development of next-generation integrated dielectric devices.

Micro/nanoprocessing of materials using lasers is currently an active research topic. In that research, the choice of the laser to be used is critical, but the F2 laser, which has the shortest wavelength (157 nm) among commercially available lasers, has few research compared to its potential. In this paper, we discovered a new photochemical processing by using an F2 laser to irradiate an amorphous carbon thin film. The short wavelength and high photon energy of the F2 laser can photoexcite the surface of the thin film at high density and generate active oxygen atoms O(1D) by photodecomposition of atmospheric oxygen molecules. As a result, the optical change of the amorphous carbon thin film was induced without thickness reduction, and a micron-sized network-like, reticulated structural change was formed in the thin film surface after one month at the latest. The formed micron-sized reticulated structure was relatively swollen, and a graphitization occurred in the structure, observed by Raman spectroscopy. However, the structure was not observed when the laser irradiated area became smaller. This work has made it possible to form a micron-sized reticulated structure including carbon nanocrystals in an amorphous carbon, which is expected to further expand the applications of carbon materials.

Abstract Molecular redox compounds show promise for the development of solid contact ion selective electrodes (SC‐ISEs) for anion determinations. In this work, a hydrophobic bis‐tridentate Ru‐bipod complex was studied as a molecular redox transducer in voltammetric SC‐ISEs. Thin film voltammetric behavior was achieved in films comprised of the Ru‐bipod complex, polyvinylchloride (PVC) and a plasticiser, nitrophenyloctylether (NPOE). Importantly, the choice of plasticiser had a significant effect on the SC‐ISE response of the Ru‐bipod complex; i. e., voltammetric responses of the Ru‐bipod complex in NPOE films were sharper and more intense than in bis(2‐ethylhexyl) sebacate (DOS) films. Moreover, addition of tetradodecylammonium tetrakis(4‐chlorophenyl)borate (ETH 500) to the membrane had an unfavorable impact on detection of anions due to oxidation of this salt in the film. Although the thin film electrode showed close‐to‐Nernstian behavior in anion responses, the detection responses in the presence of very hydrophilic anions such as sulfate ion were shifted to higher potentials (>1 V) with a subsequent loss of sensitivity. Overall, the Ru‐bipod complex operates as a simple transducer in SC‐ISEs with benefits in anion detection.

The paper presents the fabrication and characterization of [CuI(L)]n thin films, where L represents various alkylpyridine ligands including 4-methylpyridine, 3-methylpyridine, 2-methylpyridine, 4-tbutylpyridine, 3,4-dimethylpyridine, and 3,5-dimethylpyridine. The thin films were synthesized by exposing the corresponding ligands to CuI thin films through vapor deposition. The coordination reactions occurring on the films were investigated using PXRD and time-dependent photoluminescence spectroscopy, and a comparison was made between the structures of the thin films and the corresponding powder phases. The films showed primarly blue emission (λem = 457–515 nm) and polymeric structures with excited state lifetimes ranging from 0.6 to 5.5 μs. Significantly, the studied compounds exhibited fast reversible luminescence quenching when exposed to vapors of dichloromethane and dibromomethane (15 and 30 min respectively), and the luminescence was restored upon re-exposure to the alkylpyridine ligand (after 20 min). These findings indicate that these thin films hold promise for applications as sensors (with sensitive and reversible detection capability) for volatile halogen-based compounds (VHC).

This work focused on developing optical coatings for decorative applications that remain transparent in the radiofrequency range. To achieve this, a combination of dielectric material (silicon-aluminum nitride, SiAlNx) and low-electrical-conductivity semiconductor material (germanium) was utilized. Germanium plays a crucial role in providing absorption in the visible spectrum, facilitating the design of coatings with various aesthetic appearances, while allowing for control over their transmittance. The optical properties of thin germanium layers were thoroughly characterized and leveraged to create multilayer designs with diverse aesthetic features. Different multilayer structures were designed, fabricated, and optically characterized, resulting in coatings with metallic gray, black, or various colors in reflection, while retaining the ability to transmit visible light for illumination and signaling applications. Finally, the radiofrequency attenuation of the developed coatings was measured, revealing negligible attenuation; this is in stark contrast to the metallic coatings used for decorative purposes, which can attenuate by up to 30 dB.

Mn5Ge3 is a ferromagnetic phase of the Mn-Ge system that is a potential contact material for efficient spin injection and detection. Here, we investigate the creation of Mn5Ge3-based contacts on a Ge/SiGe quantum well heterostructure via solid-state synthesis. X-ray diffraction spectra fitting indicates the formation of Mn5Ge3-based contacts on bulk Ge and Ge/SiGe. High-resolution scanning transmission electron microscopy imaging and energy dispersive X-ray spectroscopy verify the correct Mn5Ge3-based phase formation. Schottky diode measurements, transmission line measurements, and Hall measurements reveal that Mn5Ge3-based contacts serve as good p-type contacts for Ge/SiGe quantum well heterostructures due to having a low Schottky barrier height of 0.10eV (extracted from a Mn5Ge3/n-Ge analogue) and a contact resistance in the order of 1 kΩ. Furthermore, we show that these electrical characteristics have a gate-voltage dependence, thereby providing tunability.

Exploring the utilization of ion exchange membranes (IEMs) in salinity gradient energy harvesting, a technique that capitalizes on the salinity difference between seawater and freshwater to generate electricity, this study focuses on optimizing PVDF to Nafion ratios to create ultra-thin membranes. Specifically, our investigation aligns with applications such as reverse electrodialysis (RED), where IEMs facilitate selective ion transport across salinity gradients. We demonstrate that membranes with reduced Nafion content, particularly the 50:50 PVDF:Nafion blend, retain high permselectivity comparable to those with higher Nafion content. This challenges traditional understandings of membrane design, highlighting a balance between thinness and durability for energy efficiency. Voltage–current analyses reveal that, despite lower conductivity, the 50:50 blend shows superior short-circuit current density under salinity gradient conditions. This is attributed to effective ion diffusion facilitated by the blend’s unique microstructure. These findings suggest that blended membranes are not only cost-effective but also exhibit enhanced performance for energy harvesting, making them promising candidates for sustainable energy solutions. Furthermore, these findings will pave the way for advances in membrane technology, offering new insights into the design and application of ion exchange membranes in renewable energy.

In this study, ZnO thin films doped with Al (AZO) and Cu (CZO) were fabricated on a glass substrate via sol-gel spin coating. The influence of 1 atomic % Al and Cu doping on the structure, morphology, as well as optical properties of ZnO thin film was then analyzed with X-ray diffraction (XRD), atomic force microscopy (AFM), and UV-Vis spectroscopy. XRD analysis revealed that all samples possessed hexagonal wurtzite crystal structures with 3 to 4 preferred orientations. Al and Cu doping caused a decrease in crystal size, while the lattice strain (e) and dislocation density (ρ) were increased. AFM indicated that Al and Cu doping reduced the surface roughness of the ZnO thin film. Optical measurement showed that all samples exhibited high transmittance (> 80%) in the visible light region. Transmittance was reduced after doping, while the band gaps for ZnO, AZO, and CZO thin films are 3.26, 3.28, and 3.23 eV. This study showed that an addition of 1 atomic % transition metal (Al and Cu) greatly influences the structure, morphology, and optical properties of ZnO thin film.

This scientific investigation emphasizes the essential integration of nature’s influence in crafting multifunctional surfaces with bio-inspired designs for enhanced functionality and environmental advantages. The study introduces an innovative approach, merging color decoration, humidity sensing, and antiviral properties into a unified surface using chitosan, an organo-biological polymer, to create cost-effective multilayered films through sol-gel deposition and UV photoinduced deposition of metal nanoparticles. The resulting chitosan films showcase diverse structural colors and demonstrate significant antiviral efficiency, with a 50% and 85% virus inhibition rate within a rapid 20 min reaction, validated through fluorescence cell expression and real-time qPCR (polymerase chain reaction) assays. Silver-deposited chitosan films further enhance antiviral activity, achieving remarkable 91% and 95% inhibition in independent assays. These films exhibit humidity-responsive color modifications across a 25–90% relative humidity range, enabling real-time monitoring validated through simulation studies. The proposed three-in-one functional surface can have versatile applications in surface decoration, medicine, air conditioning, and the food industry. It can serve as a real-time humidity sensor for indoor and outdoor surfaces, find use in biomedical devices for continuous humidity monitoring, and offer antiviral protection for frequently handled devices and tools. The customizable colors enhance visual appeal, making it a comprehensive solution for diverse applications.

The big data era demands an efficient and permanent data storage technology with the capacity of PB to EB scale. Optical data storage (ODS) offers a good candidate for long-lifetime storage, as the developing far-field super-resolution nanoscale writing technology improves its capacity to the PB scale. However, methods to efficiently read out this intensive ODS data are still lacking. In this paper, we demonstrate a sub-diffraction readout method based on polarization modulation, which experimentally achieves the sub-diffraction readout on Disperse Red 13 thin film with a resolution of 500 nm, exceeding the diffraction limit by 1.2 times (NA = 0.5). Differing from conventional binary encoding, we propose a specific polarization encoding method that enhances the capacity of ODS by 1.5 times. In the simulation, our method provides an optical data storage readout resolution of 150 nm, potentially to 70 nm, equivalent to 1.1 PB in a DVD-sized disk. This sub-diffraction readout method has great potential as a powerful readout tool for next-generation optical data storage.

Wettability, typically estimated through the contact angle, is a fundamental property of surfaces with wide-ranging implications in both daily life and industrial processes. Recent scientific interest has been paid to the surfaces exhibiting extreme wettability: superhydrophobic and superhydrophilic surfaces, characterized by high water repellency and exceptional water wetting, respectively. Both chemical composition and morphology play a role in the determination of the wettability “performance” of a surface. To tune surface-wetting properties, we considered coatings of carbon nanoparticles (CNPs) in this study. They are a new class of nanomaterials synthesized in flames whose chemistry, dimension, and shape depend on combustion conditions. For the first time, we systematically studied the wettability of CNP coatings produced in a controlled rich ethylene/air flame stabilized over a McKenna burner. A selected substrate was intermittently inserted in the flame at 15 mm above the burner to form a thin coating thanks to a thermophoretic-driven deposition mechanism. The chemical-physical quality and the deposed quantity of the CNPs were varied by opportunely combing the substrate flame insertion number (from 1 to 256) and the carbon-to-oxygen ratio, C/O (from 0.67 to 0.87). The wettability of the coatings was evaluated by measuring the contact angle, CA, with the sessile drop method. When the C/O = 0.67, the CNPs were nearly spherical, smaller than 8 nm, and always generated hydrophilic coatings (CA < 35°). At higher C/O ratios, the CNPs reached dimensions of 100 nm, and fractal shape aggregates were formed. In this case, either hydrophilic (CA < 76°) or superhydrophobic (CA ~166°) behavior was observed, depending on the number of carbon nanoparticles deposed, i.e., film thickness. It is known that wettability is susceptible to liquid surface tension, and therefore, tests were conducted with different fluids to establish a correlation between the flame conditions and the nanostructure of the film. This method offers a fast and simple approach to determining mesoscale information for coating roughness and topographical homogeneity/inhomogeneity of their surfaces.

Thin film technology shows great promise in fabricating electronic devices such as gas sensors. Here, we report the fabrication of surface acoustic wave (SAW) sensors based on thin films of (1 − x) Ba(Ti0.8Zr0.2)O3−x(Ba0.7Ca0.3)TiO3 (BCTZ50, x = 50) and Polyethylenimine (PEI). The layers were deposited by two laser-based techniques, namely pulsed laser deposition (PLD) for the lead-free material and matrix assisted pulsed laser evaporation (MAPLE) for the sensitive polymer. In order to assay the impact of the thickness, the number of laser pulses was varied, leading to thicknesses between 50 and 350 nm. The influence of BCTZ film’s crystallographic features on the characteristics and performance of the SAW device was studied by employing substrates with different crystal structures, more precisely cubic Strontium Titanate (SrTiO3) and orthorhombic Gadolinium Scandium Oxide (GdScO3). The SAW sensors were further integrated into a testing system to evaluate the response of the BCTZ thin films with PEI, and then subjected to tests for N2, CO2 and O2 gases. The influence of the MAPLE’s deposited PEI layer on the overall performance was demonstrated. For the SAW sensors based on BCTZ/GdScO3 thin films with a PEI polymer, a maximum frequency shift of 39.5 kHz has been obtained for CO2; eight times higher compared to the sensor without the polymeric layer.

We present the stabilization of halide-terminated Ge nanoparticles prepared via a disproportionation reaction of metastable Ge(I)X solutions with well-defined size distribution. Further tailoring of the stability of the Ge nanoparticles was achieved using variations in the substituent. Ge nanoparticles obtained in this way are readily dispersed in organic solvents, long-term colloidally stable, and are perfect prerequisites for thin-film preparation. This gives these nanomaterials a future in surface-dependent optical applications, as shown for the halide-terminated nanoparticles.

Transparent ZnMn2O4 thin films on indium tin oxide (ITO) were prepared through spray pyrolysis and implemented as electrodes in symmetric supercapacitors (SSCs). A specific capacitance value of 752 F g−1 at 0.5 A g−1 and a 70% retention over 3000 galvanostatic charge–discharge (GCD) cycles were reached with a 1.0 M Na2SO4 electrolyte in a three-electrode electrochemical cell. Analysis of the cycled electrodes with 1.0 M Na2SO4 revealed a local loss of electrode material; this loss increases when electrodes are used in SCCs. To avoid this drawback, solid polyvinylpyrrolidone-LiClO4 (PVP-LiClO4) and quasi-solid polyvinylpyrrolidone-ionic liquid (PVP-ionic liquid) electrolytes were tested in SSCs as substitutes for aqueous Na2SO4. An improvement in capacitance retention without a loss of electrode material was observed for the PVP-ionic liquid and PVP-LiClO4 electrolytes. With these non-aqueous electrolytes, the tetragonal structure of the ZnMn2O4 spinel was maintained throughout the cyclic voltammetry (CV) cycles, although changes occurred in the stoichiometry from ZnMn2O4 to Mn-rich Zn1−xMn3−xO4. In the case of the electrolyte 1.0 M Na2SO4, the loss of Zn2+ led to the formation of MnO2 via Zn1-xM3-xO4. The location of the three SCCs in the Ragone plot shows supercapacitor behavior. The electrochemical results prove that the pseudocapacitance is the major contributor to the electrode capacitance, and the SCCs can therefore be considered as pseudocapacitors.

This study explores the controlled laser ablation and corresponding properties of silicon nanoparticles (Si NP) with potential applications in ultraviolet (UV) light sensing. The size distribution of Si NPs was manipulated by adjusting the laser scanning speed during laser ablation of a silicon target in a styrene solution. Characterization techniques, including transmission electron microscopy, Raman spectroscopy, and photoluminescence analysis, were employed to investigate the Si NP structural and photophysical properties. Si NP produced at a laser scanning speed of 3000 mm/s exhibited an average diameter of ~4 nm, polydispersity index of 0.811, and a hypsochromic shift in the Raman spectrum peak position. Under photoexcitation at 365 nm, these Si NPs emitted apparent white light, demonstrating their potential for optoelectronic applications. Photoluminescence analysis revealed biexponential decay behavior, suggesting multiple radiative recombination pathways within the nanoscale structure. Furthermore, a thin film containing Si NP was utilized as a passive filter for a 2nd generation CCD detector, expanding the functionality of the non-UV-sensitive detectors in optics, spectrometry, and sensor technologies.

SiOx thin films were prepared using magnetron sputtering with different O2 flow rates on a silicon substrate. The samples were characterized using Fourier transform infrared spectroscopy in transmission and reflection, covering a spectral range of 5 to 25 μm. By employing a multilayer model, the values of the complex refractive index that best fit the experimental transmission and reflection results were optimized using the Brendel–Bormann oscillator model. The results demonstrate the significance of selecting an appropriate range of O2 flow rates to modify the SiOx stoichiometry, as well as how the refractive index values can be altered between those of Si and SiO2 in the mid-infrared range.

Ultra-thin solar cells enable materials to be saved, reduce deposition time, and promote carrier collection from materials with short diffusion lengths. However, light absorption efficiency in ultra-thin solar panels remains a limiting factor. Most methods to increase light absorption in ultra-thin solar cells are either technically challenging or costly, given the thinness of the functional layers involved. We propose a cost-efficient and lithography-free solution to enhance light absorption in ultra-thin solar cells—a Tsuchime-like self-forming nanocrater (T-NC) aluminum (Al) film. T-NC Al film can be produced by the electrochemical anodization of Al, followed by etching the nanoporous alumina. Theoretical studies show that T-NC film can increase the average absorbance by 80.3%, depending on the active layer’s thickness. The wavelength range of increased absorption varies with the active layer thickness, with the peak of absolute absorbance increase moving from 620 nm to 950 nm as the active layer thickness increases from 500 nm to 10 µm. We have also shown that the absorbance increase is retained regardless of the active layer material. Therefore, T-NC Al film significantly boosts absorbance in ultra-thin solar cells without requiring expensive lithography, and regardless of the active layer material.

The polycrystalline SrTiO3 thin films were prepared by the sol-gel-hydrothermal method on glass substrates. The synthesis pathway was initiated by preparing a clear TiO2 solution using the sol-gel method. This clear solution was then deposited on a glass substrate using the dip coating technique, followed by the transformation of a thin layer of TiO2 into SrTiO3 by the hydrothermal method. The crystal structure, bond interactions, and band gap energy of SrTiO3 thin layers were characterized using X-ray Diffraction (XRD), Fourier Transform Infra-Red spectroscopy (FTIR), and UV–Vis Diffuse Reflectance Spectroscopy (UV-DRS). The XRD patterns of all SrTiO3 thin layers indicated the perovskite structure of the samples. The FTIR spectrum showed an interaction of the silanol groups on the surface of the glass substrate with Ti–O–Ti of SrTiO3 layers. The characteristics of the UV-DRS spectrum were influenced by the thickness of the SrTiO3 layer formed on the glass substrate. The findings of this work provide insights for producing SrTiO3 layers with specified thickness and morphology.

Spark plasma sintering technique is used for the fabrication of dense materials with a fine-grained microstructure. In this process, a powder is placed into a graphite mold and a uniaxial pressure is applied by two graphite punches. A graphite foil is inserted between the punches and the powder and between the mold and the powder to ensure good electrical, physical and thermal contact. One of the major drawbacks during sintering of metal powders is the carburization of the powder in contact with the graphite foils. In this study, a PVD coating of titanium was applied on the graphite foils in contact with the metal powder (pure iron). The results are promising, as the investigations show that the application of a Ti PVD film of 1.5 and 1.1 µm thickness is effective to completely avoid the carburization of iron powder. Carbon diffuses inside the PVD film during sintering. In parallel, iron diffusion was revealed inside the Ti coating of 1.5 µm thickness. On the other hand, a Ti PVD film of 0.5 µm thickness provides a protection against carbon diffusion just on the sides in contact with the mold, proving that the coating thickness represents an important parameter to consider.

OEMT is an existing optimizing envelope method for thin-film characterization that uses only one transmittance spectrum, T(λ), of the film deposited on the substrate. OEMT computes the optimized values of the average thickness, d¯, and the thickness non-uniformity, Δd, employing variables for the external smoothing of T(λ), the slit width correction, and the optimized wavelength intervals for the computation of d¯ and Δd, and taking into account both the finite size and absorption of the substrate. Our group had achieved record low relative errors, d¯ of thin semiconductor films via OEMT, whereas the high accuracy of d¯ and Δd allow for the accurate computation of the complex refractive index, N˙(λ), of the film. In this paper is a proposed envelope method, named OEMR, for the characterization of thin dielectric or semiconductor films using only one quasi-normal incidence UV/Vis/NIR reflectance spectrum, R(λ), of the film on the substrate. The features of OEMR are similar to the described above features of OEMT. OEMR and several popular dispersion models are employed for the characterization of two a-Si films, only from R(λ), with computed d¯ = 674.3 nm and Δd = 11.5 nm for the thinner film. It is demonstrated that the most accurate characterizations of these films over the measured spectrum are based on OEMR.

The purpose of the presented study is to examine the impact of zinc oxide nanoparticles (ZnO NPs) on the spectrum features of poly [2-methoxy-5-(3′,7′-dimethyloctyloxy)-1, 4-phenylenevinylene] (MDMO-PPV). The characteristics of the MDMO-PPV and doped ZnO NPS samples were assessed using several techniques. A set of solutions of MDMO-PPV in toluene that were doped with different ratio percentages of ZnO NPs was prepared to obtain thin films. Pristine and composite solutions were spin-coated on glass substrates. It was observed that MDMO-PPV had two distinct absorbance bands at 310 and 500 nm in its absorption spectrum. The UV-Vis spectrum was dramatically changed when 5% of ZnO NPs were added. The result showed a significant reduction in absorption of the band 500 nm, while 310 nm absorption increased rapidly and became more pronounced. Upon adding (10%) ZnONPs to the sample, no noticeable change was observed in the 500 nm band. However, the 310 nm band shifted towards the blue region. There is a dominant peak in the PL spectrum of MDMO-PPV in its pristine form around 575 nm and a smaller hump around 600 nm of the spectrum. The spectral profile at 600 nm and the intensity of both bands are improved by raising the ZnO NP concentration. These bands feature two vibronic transitions identified as (0-0) and (0-1). When the dopant concentration increased to the maximum dopant percentage (10%), the energy band gap values increased by 0.21 eV compared to the pristine MDMO-PPV. In addition, the refractive index (n) decreased to its lowest value of 2.30 with the presence of concentrations of ZnO NPs.

Thin nanocrystalline transparent Al-doped ZnO (1–10 at.% Al) films were synthesized by solid-phase pyrolysis at 700 °C. Synthesized Al-doped ZnO films were investigated by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM, TEM). All obtained materials were crystallized into the wurtzite structure, which was confirmed by XRD. The material crystallinity decreases with the introduction of aluminum. SEM and TEM showed that the films are continuous and have a uniform distribution of nanoparticles with an average size of 15–20 nm. TEM confirmed the production of Al-doped ZnO films. The transmittance of Al-doped ZnO films in the range of 400–1000 nm is more than 94%. The introduction of 1% Al into ZnO leads to a narrowing of the band gap compared to ZnO to a minimum value of 3.26 eV and a sharp decrease in the response time to the radiation exposure with a wavelength of 400 nm. An increase in aluminum concentration leads to a slight increase in the band gap, which is associated with the Burstein–Moss effect. The minimum response time (8 s) was shown for film containing 10% Al, which is explained by the shortest average lifetime of charge carriers (4 s).

The synthesis of cupric oxide (CuO) films on cost-efficient, optical grade borosilicate-crown glass substrates (BK7) via chemical spray pyrolysis (CSP), either in pure form or with a low concentration of Al doping (below 1%), is presented and discussed. As a non-toxic p-type semiconductor, exhibiting monoclinic crystal structure and widely tuneable band gap (Eg), it is used in various applications. The optical properties, morphology and crystalline phases of CuO films are influenced by substrate temperature during thin film growth (annealing) and also by chemical doping very often introduced to modify grain boundary energy. The importance of our research subject is therefore perfectly justified and is essentially based on the fact that the potential fields of application are wide. Thus, herein we emphasize impact of the annealing stage and Al doping upon the structural, optical and electrical properties of the resulting product. Raman spectroscopy analysis confirms the presence of vibrational bands characteristic of a CuO phase, while X-ray diffraction (XRD) confirms the polycrystalline nature of the pure films. The thickness of the CuO films grown at 350 °C over three annealing intervals is proportional to the annealing time, while the crystallite phase in the films is proportional with the annealing temperature. Furthermore, XRD analysis of the Al:CuO films indicates the formation of a monoclinic-type structure (CuO phase) exhibiting a preferred orientation along the (002) plane, together with a significant grain size reduction from ~88 to ~45 nm as Al content increases. The transmittance spectra (between 400 and 800 nm) reveal a decrease in the transmittance from 48% to 15% with as the Al doping ratio increases. Additionally, the bandgap energy of the films is measured, modelled and discussed, using data from an ultraviolet–visible (UV-Vis) spectrophotometer. The calculated Eg is approximately 3.5 eV, which decreases with respect to the increasing annealing temperature, while the electrical resistivity varies from ~19 to ~4.6 kOhm.cm. Finally, perspectives and applications of CuO films are suggested, since the films are found to have a remarkable improvement in their structure and optical properties when doped with Al.

In the last few years, imidazo[1,5-a]pyridine scaffolds and derivatives have attracted growing attention due to their unique chemical structure and optical behaviors. In this work, a series of pyridylimidazo[1,5-a]pyridine derivatives and their corresponding pyridinium salts were synthesized and their optical properties investigated to evaluate the effect of the quaternization on the optical features both in solution and polymeric matrix. A critical analysis based on the spectroscopic data, chemical structures along with density functional theory calculation is reported to address the best strategies to prevent aggregation and optimize the photophysical properties. The obtained results describe the relationship between chemical structure and optical behaviors, highlighting the role of pendant pyridine. Finally, the presence of a positive charge is fundamental to avoid any possible aggregation process in polymeric films.

Organo-lead halide perovskites have recently attracted great interest for potential applications in thin-film photovoltaics and optoelectronics. Herein, we present a protocol for the fabrication of this material via the low-pressure vapor assisted solution process (LP-VASP) method, which yields ~19% power conversion efficiency in planar heterojunction perovskite solar cells. First, we report the synthesis of methylammonium iodide (CH3NH3I) and methylammonium bromide (CH3NH3Br) from methylamine and the corresponding halide acid (HI or HBr). Then, we describe the fabrication of pinhole-free, continuous methylammonium-lead halide perovskite (CH3NH3PbX3 with X = I, Br, Cl and their mixture) films with the LP-VASP. This process is based on two steps: i) spin-coating of a homogenous layer of lead halide precursor onto a substrate, and ii) conversion of this layer to CH3NH3PbI3-xBrx by exposing the substrate to vapors of a mixture of CH3NH3I and CH3NH3Br at reduced pressure and 120 °C. Through slow diffusion of the methylammonium halide vapor into the lead halide precursor, we achieve slow and controlled growth of a continuous, pinhole-free perovskite film. The LP-VASP allows synthetic access to the full halide composition space in CH3NH3PbI3-xBrx with 0 ≤ x ≤ 3. Depending on the composition of the vapor phase, the bandgap can be tuned between 1.6 eV ≤ Eg ≤ 2.3 eV. In addition, by varying the composition of the halide precursor and of the vapor phase, we can also obtain CH3NH3PbI3-xClx. Films obtained from the LP-VASP are reproducible, phase pure as confirmed by X-ray diffraction measurements, and show high photoluminescence quantum yield. The process does not require the use of a glovebox.

Coatings with tunable refractive index and high mechanical resilience are useful in optical systems. In this work, thin films of HfO2 doped with Al2O3 were deposited on silicon at 300 °C by using plasma-enhanced atomic layer deposition (PE-ALD). The mainly amorphous 60–80 nm thick films consisted Al in the range of 2 to 26 at.%. The refractive indexes varied from 1.69 to 2.08 at the wavelength of 632 nm, and they consistently depended on the composition. The differences were higher in the UV spectral region. At the same time, the hardness of the films was from 12–15 GPa; the modulus was in the range of 160–180 GPa; and the mechanical properties did not have a good correlation with the deposited compositions. The deposition conditions, element contents, and refractive indexes at respective wavelengths were correlated. The results indicated that it is possible to tune optical properties and retain mechanical properties of atomic layer-deposited thin films of HfO2 with Al2O3 as doping oxide. Such films could be used as mechanically resilient and optically tunable coatings in, for instance, micro- or nano-electromechanical systems or transparent displays.

The adhesive bonds that ensure the appropriate mechanical properties for metal joining imply the surface chemical and wetting modification characteristics of the substrates. In this work, matrix-assisted pulsed laser evaporation (MAPLE) was used for the surface modification of Al via the deposition of two chemical compounds, polyvinyl alcohol (PVA) and triethanolamine (TEA), from frozen aqueous solutions. The deposition of the TEA and PVA layers was evidenced by FT-IR, SEM, and AFM analysis. The contact angle measurements evidenced the change in the hydrophilicity of the surface and surface free energies. The performance of the commercial silyl-based polymer adhesive Bison Max Repair Extreme Adhesive® was evaluated by tensile strength measurements. This method led to a change in tensile strength of 54.22% in the case of Al-TEA and 36.34% for Al-PVA compared with the control. This study gives preliminary insights into using MAPLE, for the first time in adhesive applications, as a pretreatment method for Al plates for adhesive bonding reinforcement.

A novel method for the preparation of Ni-Cu oxide catalysts—deposition on stainless steel meshes using hollow cathode plasma jet sputtering—was studied. This method allows the preparation of thin oxide films. Consequently, the whole volume of the active phase is readily accessible for the reactants and can be employed in the catalytic reaction due to the negligible effect of internal diffusion. As a result, the activity of our sputtered catalyst was seven times higher in ethanol oxidation and 61 times higher in toluene oxidation than that of the corresponding granular catalyst. Moreover, due to stainless steel meshes used as a catalyst support, the pressure drop across the catalyst bed was lower. Finally, the catalytic activity of the sputtered Ni-Cu oxide catalyst with Ni:Cu molar ratio of 1:1 in ethanol oxidation was 1.7 times higher than that of the commercial EnviCat® VOC-1544 catalyst, while the amount of the active phase in the catalyst bed was 139 times lower. The outstanding performance of the Ni0.5Cu0.5 catalyst was ascribed to the synergistic effect between the copper and nickel components.

The work is dedicated to study of thin V2O5 film formation by pen plotter printing using vanadyl alkoxyacetylacetonate as hydrolytically active precursor. Solution of the prepared vanadyl butoxyacetylacetonate complex with 87% of butoxyl groups was used as functional ink for pen plotter printing of thin V2O5 film on surface of specialized chip. According to atomic force microscopy (AFM) and scanning electron microscopy (SEM), oxide film consists of nanorods 35–75 nm in thickness and 120–285 nm in length, with crystallite size of 54 ± 4 nm. Data from Rietveld refinement of the X-ray powder diffraction results and work function value (4.54 eV) indicate high content of defects (such as oxygen vacancies) in the material. Electrophysical properties study suggests that correlated barrier hopping of the charge carriers is the main conductivity mechanism. Conductivity activation energy Ea was found to be 0.24 eV.

Remarkable improvement in the perovskite solar cell efficiency from 3.8% in 2009 to 25.5% today has not been a cakewalk. The credit goes to various device fabrication and designing techniques employed by the researchers worldwide. Even after tremendous research in the field, phenomena such as ion migration, phase segregation, and spectral instability are not clearly understood to date. One of the widely used techniques for the mitigation of ion migration is to reduce the defect density by fabricating the high-quality perovskite thin films. Therefore, understanding and controlling the perovskite crystallization and growth have become inevitably crucial. Some of the latest methods attracting attention are controlling perovskite film morphology by modulating the coating substrate temperature, antisolvent treatment, and solvent engineering. Here, the latest techniques of morphology optimization are discussed, focusing on the process of nucleation and growth. It can be noted that during the process of nucleation, the supersaturation stage can be induced faster by modifying the chemical potential of the system. The tailoring of Gibbs free energy and, hence, the chemical potential using the highly utilized techniques is summarized in this minireview. The thermodynamics of the crystal growth, design, and orientation by changing several parameters is highlighted.

Abstract Integration of metal‐organic frameworks (MOFs) as components of advanced electronic devices is at a very early phase of development and the fundamental issues related to their crystal growth on conductive substrate need to be addressed. Herein, we report on the structural characterization of a newly synthesized Sr‐based MOF {[Sr(2,5‐Pzdc)(H2O)2] ⋅ 3 H2O}n (1) and the uniform crystal growth of compound 1 on a conducting glass (fluorine doped tin oxide (FTO)) substrate using electrochemical deposition techniques. The Sr‐based MOF 1 was synthesized by the reaction of Sr(NO3)2 with 2,5‐pyrazinedicarboxylic acid dihydrate (2,5‐Pzdc) under solvothermal conditions. A single‐crystal X‐ray diffraction analysis revealed that 1 has a 3D structure and crystallizes in the triclinic P1‾ space group. In addition, the uniform crystal growth of this MOF on a conducting glass (FTO) substrate was successfully achieved using electrochemical deposition techniques. Only a handful of MOFs have been reposed to grown on conductive surfaces, which makes this study an important focal point for future research on the applications of MOF‐based devices in microelectronics.

In this study, we report on the fabrication and characterization of cobalt oxide (Co3O4) thin film that is potentially important for electrochemical capacitor applications. For that purpose, the precursor powder of Co3O4 was prepared using the cost-effective sol-gel synthesis route and heat treatment at a relatively low temperature. A thin film of Co3O4 was prepared on a fluorine-doped tin oxide (FTO) substrate using a simple doctor-blade method. X-ray diffraction and Raman spectroscopy confirmed the formation of pure Co3O4 thin film on FTO, and scanning and transmission electron microscopy confirmed the nanoscale nature of the particles in the film. The electrochemical studies revealed a specific capacitance of 237 ​F ​g-1 for the Co3O4 electrode, with a remarkable cycling stability in 1 ​M NaOH electrolyte, and 77% capacity retention after 2000 cycles at 5 ​mA ​cm-2 current density (833 ​mA ​g-1); this demonstrates that Co3O4 is a promising material for electrochemical devices. Further, the electrochemical impedance measurements revealed an internal (solution) of 10 ​Ω, whereas the charge transfer resistance between the electrode and the electrolyte was roughly 40 ​Ω.

Epitaxial n-type infrared transparent conductive Bi2Se3 thin film was cultivated by molecular beam epitaxy (MBE) method on Al2O3 (001) substrate. The orientation between Bi2Se3 and the substrate is Bi2Se3(001)//Al2O3(1 2¯ 10). Conducting mechanism ensued the small-polaron hopping mechanism, with an activation energy of 34 meV. The film demonstrates conductivity of n-type, and the resistivity is 7 × 10−4 Ωcm at room temperature. The Film exhibits an excellent carrier mobility of 1,015 cm2/Vs at room temperature and retains optical transparency in the near-infrared (>70%) and far-infrared (>85%) ranges. To the best of our knowledge, the Bi2Se3 film yields the best result in the realm of n-type Infrared transparent conductive thin films generated through either physical or chemical methods. To demonstrate the application of such films, we produced N-Bi2Se3/P-CuScO2 heterojunction diode device, the ∼3.3 V threshold voltage of which conformed fairly well with the CuScO2 bandgap value. The high optical transparency and conductivity of Bi2Se3 film make it very promising for optoelectronic applications, where a wide wavelength range from near-infrared to far-infrared is required.

As compared to other deposition techniques such as atomic layer deposition, chemical vapour deposition and sputtering, aerosol deposition (AD) is a simple and cost-effective technique to produce ZnO thin films. In this work, the effect of deposition cycles on the structural, optical, and photo-conversion efficiency (PCE) of dye sensitized solar cells of ZnO thin films deposited by AD (AZ) was systematically studied. The structural, optical, and PCE% of two-cycle deposited ZnO thin film (AZ-II) exhibited the highest performance. Further increment in deposition cycle caused deterioration in the structural, optical, and PCE performance. The thickness of ZnO thin films decreased due to abrasion of the deposited film by the subsequent stream of highly energetic ZnO particles. Loosely bound particles could be found on the surface of ZnO thin film after three deposition cycles (AZ-III). The AZ-III films exhibited poor crystal quality, with many crystal defects such as interstitial oxygen as suggested in room temperature photoluminescence analysis.

We describe a new approach to making ultrathin Ag nanoshells with a higher level of extinction in the infrared than in the visible. The combination of near-infrared active ultrathin nanoshells with their isotropic optical properties is of interest for energy-saving applications. For such applications, the morphology must be precisely controlled, since the optical response is sensitive to nanometer-scale variations. To achieve this precision, we use a multi-step, reproducible, colloidal chemical synthesis. It includes the reduction of Tollens’ reactant onto Sn2+-sensitized silica particles, followed by silver-nitrate reduction by formaldehyde and ammonia. The smooth shells are about 10 nm thick, on average, and have different morphologies: continuous, percolated, and patchy, depending on the quantity of the silver nitrate used. The shell-formation mechanism, studied by optical spectroscopy and high-resolution microscopy, seems to consist of two steps: the formation of very thin and flat patches, followed by their guided regrowth around the silica particle, which is favored by a high reaction rate. The optical and thermal properties of the core-shell particles, embedded in a transparent poly(vinylpyrrolidone) film on a glass substrate, were also investigated. We found that the Ag-nanoshell films can convert 30% of the power of incident near-infrared light into heat, making them very suitable in window glazing for radiative screening from solar light.

Back focal plane (BFP) ellipsometry, which acquires the ellipsometric parameters of reflected light at different incident and azimuthal angles through a high-NA objective lens, has recently shown great potential in industrial film measurement. In on-line metrology cases for film manufacturing, the film vibration, which is caused by equipment vibrations or environmental disturbances, results in defocus blur and distortion of the received BFP images. Thus, subsequently extracted ellipsometric spectra and film parameters significantly deviate from the ground truth values. This paper proposes a cost-effective method for correcting vibration-induced BFP ellipsometric spectral errors. The method relies on an initial incident angle calibration of BFP radii at different defocus positions. Then, corresponding ellipsometric spectral errors are corrected by inserting a calibrated Jones compensation matrix into a system model. During measurement, the defocus position of the vibrational film is first determined. Then, BFP ellipsometric spectral errors, including incident angle mapping distortion and ellipsometric parameter variations, are corrected for a bias-free film analysis using the previous calibration results. Experimental results showed that this method significantly improved measurement accuracy without vibrational defocus compensation, from over 30 nm down to less than 1 nm.

Due to recent advances in communication systems, dielectric and magnetic ceramics (ferrites) are attractive for use in devices. Spinel-type ferrites were the first material utilized in microwave devices; however, yttrium iron garnet (YIG) has low dielectric losses and is exploited in many applications. Owing to its high Faraday rotation, YIG films are utilized in magneto-optical applications. This study intends to examine the research trends and scientific research progress on highly cited papers discussing YIG films published between 2012 and 2022 using a bibliometric method. A comprehensive review of 100 scientific papers about YIG was performed from the Scopus database. The assessment of these highly cited papers was highlighted based on the following factors: publication trends and performance, limitations/research gaps, keywords, sub-fields, methodology journal evaluations, document type evaluation, issues, difficulties, solutions, and applications as well as guiding future YIG research. The majority of publications (99%) comprise experimental analysis, whereas 1% provide a based state-of-the-art overview. Ninety-one percent of articles focused on magnetization characterization. This bibliometric survey indicates that YIG film research is an expanding and developing field. The results of the data analysis can be utilized to improve the researchers’ understanding of YIG research and to encourage additional study in this area.

The demand for flexible large-area optoelectronic devices has been growing significantly during recent years. Roll-to-roll (R2R) printing facilitates the cost-efficient industrial production of different optoelectronic devices. Nonetheless, the performance of these devices is highly dependent on the printing quality and number of defects of R2R printed conductors. The image processing technique is an efficient nondestructive testing (NDT) methodology used to detect such defects. In this study, a computer vision-based assessment tool was utilized to visualize R2R printed silver conductors’ defects on flexible plastic substrates. A multistage defect detection technique was proposed to detect and classify both printing-induced defects and imperfections as well as the misalignment of the printed conductors with respect to the reference design. The method proved to be a very reliable approach that can be used independently or in conjunction with electrical testing methods for quality assurance purposes during the production of R2R prints.

Thermoelectric (TE) technology attracts much attention due to the fact it can convert thermal energy into electricity and vice versa. Thin-film TE materials can be synthesized on different kinds of substrates, which offer the possibility of the control of microstructure and composition to higher TE power, as well as the development of novel TE devices meeting flexible and miniature requirements. In this work, we use magnetron sputtering to deposit N-type and P-type BiTe-based thin films on silicon, glass, and Kapton HN polyimide foil. Their morphology, microstructure, and phase constituents are studied by SEM/EDX, XRD, and TEM. The electrical conductivity, thermal conductivity, and Seebeck coefficient of the thin film are measured by a special in-plane advanced test system. The output of electrical power (open-circuit voltage and electric current) of the thin film is measured by an in-house apparatus at different temperature gradient. The impact of deposition parameters and the thickness, width, and length of the thin film on the power output are also investigated for optimizing the thin-film flexible TE device to harvest thermal energy.

Mn5Ge3 epitaxial thin films previously grown mainly on Ge substrate have been synthesized on Si(111) using the co-deposition of Mn and Ge at a temperature of 390 °C. RMS roughness decreases by almost a factor of two in the transition from a completely polycrystalline to a highly ordered growth mode. This mode has been stabilized by changing the ratio of the Mn and Ge evaporation rate from the stoichiometric in the buffer layer. Highly ordered Mn5Ge3 film has two azimuthal crystallite orientations, namely Mn5Ge3 (001) [1-10] and Mn5Ge3 (001) [010] matching Si(111)[-110]. Lattice parameters derived a (7.112(1) Å) and c (5.027(1) Å) are close to the bulk values. Considering all structural data, we proposed a double buffer layer model suggesting that all layers have identical crystal structure with P6₃/mcm symmetry similar to Mn5Ge3, but orientation and level of Si concentration are different, which eliminates 8% lattice mismatch between Si and Mn5Ge3 film. Mn5Ge3 film on Si(111) demonstrates no difference in magnetic properties compared to other reported films. TC is about 300 K, which implies no significant excess of Mn or Si doping. It means that the buffer layer not only serves as a platform for the growth of the relaxed Mn5Ge3 film, but is also a good diffusion barrier.

The requirement of mounting several access points and base stations is increasing tremendously due to recent advancements and the need for high-data-rate communication services of 5G and 6G wireless communication systems. In the near future, the enormous number of these access points might cause a mess. In such cases, an optically transparent antenna (OTA) is the best option for making the environment more appealing and pleasant. OTAs provide the possible solution as these maintain the device aesthetics to achieve transparency as well as fulfill the basic coverage and bandwidth requirements. Various attempts have been made to design OTAs to provide coverage for wireless communication, particularly for the dead zones. These antennas can be installed on building windows, car windscreens, towers, trees, and smart windows, which enables network access for vehicles and people passing by those locations. Several transparent materials and techniques are used for transparent antenna design. Thin-film and mesh-grid techniques are very popular to transform metallic parts of the antenna into a transparent material. In this article, a comprehensive review of both the techniques used for the design of OTAs is presented. The performance comparison of OTAs on the basis of bandwidth, gain, transparency, transmittance, and efficiency is also presented. An OTA is the best choice in these situations to improve the aesthetics and comfort of the surroundings with high antenna performance.