Glass Substrates Research Articles

Tailoring physical properties and electrochemical performance of polyaniline thin films via chemical bath deposition

This study focuses on the properties of polyaniline (PANI) thin deposited onto glass substrates using a chemical bath method. The films were prepared under the same conditions, except for the type of oxidant used. Three oxidants were utilized: potassium per-sulfate (KPS), sodium per-iodate (NAIO4), and ferric chloride di-hydrated (FeCl3·2H2O). X-ray diffraction (XRD) analysis confirmed that all deposited films had an amorphous structure. Fourier-transform infrared spectroscopy (FT-IR) confirmed the presence of PANI films, as indicated by the recorded peaks. Scanning electron microscopy (SEM) was employed to study the surface structure and morphologies of the films, revealing nano-structured grains with varying average grain sizes depending on the oxidant type. The elemental composition of the films was analyzed using X-ray photoelectron spectroscopy (XPS). The optical band gap values were determined to be 4.06 eV, 3.93 eV, and 3.96 eV for FeCl3·2H2O, NAIO4, and KPS oxidants, respectively. The refractive index and extinction coefficient were also calculated from optical data, showing significant variations with changes in the oxidant type. The high frequency dielectric constant of the films was estimated using the Spitzer-Fan model, resulting in values of 5.15, 3.24, and 474 for FeCl3, NAIO4, and KPS oxidants, respectively. Additionally, cyclic voltammetry studies revealed that PANI/glass films grown using NAIO4 exhibited the highest specific capacity. Further investigation of PANI/FTO/glass films showed a specific capacity estimated to be 100 Fg-1 for this particular film configuration.

Catalytic strategies for uniform monolayer MoSe2 growth in CVD processes

To facilitate the widespread utilization of devices based on two-dimensional transition metal dichalcogenide (TMDC) materials, addressing the challenge of producing large-area and uniform monolayers is crucial. In this study, we investigated the efficacy of various catalysts in promoting the growth of monolayer MoSe2 through chemical vapor deposition (CVD) as a potential solution to improve surface coverage and uniformity while maintaining the monolayer structure. Five distinct water-soluble catalysts (sodium chloride (NaCl), zinc chloride (ZnCl2), potassium hydroxide (KOH), potassium chloride (KCl), potassium oxalate (K2C2O4)) were employed in conjunction with a glass substrate for the CVD-based growth of monolayer MoSe2. We applied these catalyst solutions as thin layers onto SiO2/Si substrates to observe their specific catalytic effects on monolayer MoSe2 formation. MoSe2 was selected as the target material due to its promising characteristics within the TMDC family, particularly its high mobility. Our findings revealed that NaCl, ZnCl2, KCl, and K2C2O4 catalysts enhanced monolayer growth in the 2H phase on SiO2/Si substrates, while the glass substrate resulted in a hybrid 1T/2H MoSe2 structure, albeit with the highest surface coverage. Furthermore, the use of a catalyst allowed us to bypass the laborious transfer step by enabling direct growth of the MoSe2 flakes on the Si/SiO2 substrate, eliminating the risk of flake damage arising from the transfer process. Among the catalyst solutions, NaCl yielded the most homogeneous MoSe2 monolayer growth with relatively high coverage.

Atomic Layer Deposition Growth and Characterization of Al2O3 Layers on Cu-Supported CVD Graphene

The deposition of thin uniform dielectric layers on graphene is important for its successful integration into electronic devices. We report on the atomic layer deposition (ALD) of Al2O3 nanofilms onto graphene grown by chemical vapor deposition onto copper foil. A pretreatment with deionized water (DI H2O) for graphene functionalization was carried out, and, subsequently, trimethylaluminum and DI H2O were used as precursors for the Al2O3 deposition process. The proper temperature regime for this process was adjusted by means of the ALD temperature window for Al2O3 deposition onto a Si substrate. The obtained Al2O3/graphene heterostructures were characterized by Raman and X-ray photoelectron spectroscopy, ellipsometry and atomic force and scanning electron microscopy. Samples of these heterostructures were transferred onto glass substrates by standard methods, with the Al2O3 coating serving as a protective layer during the transfer. Raman monitoring at every stage of the sample preparation and after the transfer enabled us to characterize the influence of the Al2O3 coating on the graphene film.

Effect of thickness on properties of La-doped Zinc Blende/Wurtzite ZnO thin films prepared by spray pyrolysis

Abstract Thin films of ZnO doped with 3wt% Lanthanum were deposited on glass substrates using spray pyrolysis for varying thicknesses. The impact of thickness on the physical properties of the films was investigated using various techniques. XRD results revealed the formation of a mixture of two phases, cubic Zinc Blende (ZB) and hexagonal Wurtzite (WU), with their ratios changing based on film thickness. Crystallite size measurements indicated that the cubic phase granules remained stable at 14.6 nm up to a thickness of 719 nm, decreasing to 14 nm at 846 nm, while the crystallite size of the hexagonal phase increased to 18 nm at 846 nm. FE-SEM images showed changes in surface morphology with increasing thickness, and EDX analysis demonstrated a consistent La/Zn ratio across all film thicknesses. The refractive index exhibited a shift from normal to abnormal dispersion when the thickness exceeded 719 nm, and the high-frequency dielectric constant decreased from 3.2 to 2.91 as thickness increased. Additionally, optical band gaps ranged from a minimum of 3.19 eV at 719 nm thickness to a maximum of 3.23 eV at 846 nm thickness. The study examined the effectiveness of the deposited films in blocking UV light with a wavelength of 365 nm. It was discovered that the decay time significantly decreased to 143s at a thickness of 661 nm, compared to longer times observed at other thicknesses.

Investigation of the Effect of the Passivation on the Charge Transfer from MAPbI3 to Electron Transport Layer Using a Heterodyne Transient Grating Spectroscopic Technique.

We fabricated MAPbI3perovskite thin films with ZnO on a glass substrate, in which a passivation layer (Phenethylammonium iodide (PEAI); p-methoxyphenethylammonium iodide (CH3O-PEAI); 2-methoxyethylammonium iodide (MEAI)) was inserted between two layers. In order to understand the effect of the insertion of each passivation material on the transfer efficiency of the photo-generated electrons from MAPbI3 to ZnO, we observed the near-field heterodyne transient grating (NF-HD-TG) responses of each film and investigated the component arising from the recombination of the trapped electrons at the ZnO surface. Based on the accelerated recombination between photo-generated holes remaining in the MAPbI3 layer and surface-trapped electrons in ZnO and the increase in the number of the trapped electrons in ZnO when either CH3O-PEAI or PEAI was applied, we successfully revealed that the charge transfer efficiency was enhanced by the insertion of the passivation materials including a benzene ring stabilizing the defect states. Particularly, it was demonstrated that CH3O-PEAI showed the highest increase in the charge transfer efficiency, which could be attributed to the high electron density in the benzene ring, resulting from the existence of the electron donating group, CH3O, and its role in the effective transition from 3D to 2D perovskite phases.

Introduction and application of a new approach for model-based optical bidirectional measurements

Accurate measurements of micro- and nanoscale features in optical microscopy demand comprehensive modelling approaches. In this study, we introduce an enhanced evaluation method, utilizing rigorous simulations based on a finite element method algorithm within an advanced Bayesian optimization framework. We provide an in-depth explanation of the measurement process, including the dimension reduction techniques applied to the acquired measurement data. Additionally, we employ Hopkins’ approximation or also referred to as local Hopkins’ methods for an efficient microscopic image simulation, resulting in a significant reduction of the computing time. We applied this method to measure the linewidths of six different chrome lines, nominally 300 nm–1000 nm wide, on a glass substrate. Our results show an excellent agreement with previous investigations conducted using various measurement systems, including atomic force microscopy, scanning electron microscopy, and optical microscopy in combination with different measurement evaluation techniques.

Microstructural contribution to the magnetic anisotropy in Fe1−xGax thin films: correlation between crystallographic texture and magnetic response

Abstract In this study, we present a systematic analysis of the relation between the structural properties and magnetic anisotropies of as-grown and heat-treated polycrystalline Fe1−xGax (0.11 < x < 0.19) thin films deposited on glass and Si(100) substrates. The results show that the crystallographic texture of the films has a significant impact on the evolution of the magnetic anisotropies. The samples grown on glass do not exhibit a preferred texture while, for samples grown on Si(100), the appearance of a weak in-plane fourfold magnetic anisotropy is reported. Such anisotropy is enhanced and better defined in the heat treated samples. Via a phenomenological model we show that this anisotropy has a microstructural origin. These findings demonstrate the possibility of tuning magnetic anisotropies by growing on different substrates and/or performing thermal treatments, which in turn reinforces the possibility of developing smart magnetic switching materials for electronic applications.

Fluorine-free approaches to impart photovoltaic systems with self-cleaning and anti-icing features

AbstractDust deposition on photovoltaic systems has a significant impact on the transmittance, temperature, and roughness, causing reductions in their power generation efficiency and lifetime. A promising approach to deal with this problem relies on the use of superhydrophobic coatings to impart the surfaces of these devices with self-cleaning properties. In this work, materials with different chemistry and morphology were added to an acrylic dispersion to create hydrophobic surfaces using a non-fluorinated coating simple strategy for glass substrates. Results showed that materials with more complex morphology, namely the spherical shape of silica nanoparticles, and the needle-like and prism-like structures of zinc oxide, imparted the glass with higher water contact angles. All coatings prepared displayed self-cleaning features and good adhesion to the glass substrate. Coatings comprising silica nanoparticles, zirconia and alumina modified with HDMTS were the best ones to prevent ice formation. In terms of chemical stability, all the coatings resisted acidic conditions close to acid rain pH and solvents with mild polarity. Therefore, the coatings proposed hold great potential to expel dust contaminants and prevent ice formation of photovoltaic devices, increasing their lifetime and power generation efficiency.

Temperature-Dependent Residual Stresses and Thermal Expansion Coefficient of VO2 Thin Films

This study aims to investigate the thermomechanical properties of vanadium dioxide (VO2) thin films. A VO2 thin film was simultaneously deposited on B270 and H-K9L glass substrates by electron-beam evaporation with ion-assisted deposition. Based on optical interferometric methods, the thermal–mechanical behavior of and thermal stresses in VO2 films can be determined. An improved Twyman–Green interferometer was used to measure the temperature-dependent residual stress variations of VO2 thin films at different temperatures. This study found that the substrate has a great impact on thermal stress, which is mainly caused by the mismatch in the coefficient of thermal expansion (CTE) of the film and the substrate. By using the dual-substrate method, thermal stresses in VO2 thin films from room temperature to 120 °C can be evaluated. The thermal expansion coefficient is 3.21 × 10−5 °C−1, and the biaxial modulus is 517 GPa.

Exploring the Post-Annealing Influence on Stannous Oxide Thin Films via Chemical Bath Deposition Technique: Unveiling Structural, Optical, and Electrical Dynamics

Stannous oxide (SnO2) thin films have garnered significant attention for their promising applications in various electronic and optoelectronic devices. In this study, we investigate the impact of post-annealing on the structural, optical, and electrical properties of stannous oxide thin films deposited using the chemical bath deposition (CBD) technique. The thin films were prepared on a Borosilicate glass substrate, followed by a controlled annealing process to enhance their performance. Structural analysis was conducted using techniques such as X-ray diffraction (XRD) to examine the cubic crystalline structure and the crystallite size increase induced by post-annealing. The results revealed alterations in grain size from the SEM and the purity of samples confirmed from EDX results. The optical properties of the Stannous oxide thin films were examined using UV-Vis spectroscopy. The optical absorption and bandgap characteristics were analyzed to understand how post-annealing influences the optical behavior of the thin films. Where the optical absorption was 320nm and the bandgap ranges were 3.86eV to 3.83eV. Furthermore, the electrical properties of the thin films were evaluated semiconducting nature, and conductivity increased with rising post-annealing. The findings from this study contribute to the understanding of the role of post-annealing in tailoring the properties of Stannous oxide thin films. The optimization of structural, optical, and electrical characteristics is crucial for their successful integration into electronic and optoelectronic devices.

Phenyl-Substituted Cage Silsesquioxane-Based Star-Shaped Giant Molecular Clusters: Synthesis, Properties, and Surface Segregation Behavior.

The crystallinity, solubility, and physical properties of polyhedral oligomeric silsesquioxane (POSS) compounds are highly dependent on their organic substituents. We previously synthesized a series of isobutyl-substituted star-shaped POSS derivatives with aliphatic chain linkers of different length. In this study, we prepared C3- and C6-linked phenyl-substituted star-shaped POSS derivatives (3Ph-C3 and 3Ph-C6) by the hydrosilylation of heptaphenylallyl- and hexenyl-POSS (1a and 1b) and octadimethylsiloxy-Q8-silsesquioxane (Q8M8H) (2), respectively, and their properties were compared with those of the corresponding isobutyl-substituted derivatives (5iBu-C3 and 5iBu-C6). Although 3Ph-C6 was only soluble in chloroform and insoluble in tetrahydrofuran (THF) and toluene, 3Ph-C3 was soluble even in THF and toluene, suggesting that the shorter linkers of the derivative afford a wider range of solvents for dissolution. Differential scanning calorimetry analysis showed that 3Ph-C3 exhibited a baseline shift at 190 °C and an endothermic peak at 316 °C. However, no clear baseline shift was observed for 3Ph-C6. Thermogravimetric analysis showed that the shorter linker in the phenyl-substituted star-shaped POSS derivative significantly increased the decomposition temperature compared with the longer linker. The annealed cast film of 3Ph-C3 at 340 °C above its melting temperature formed a transparent film even after cooling to room temperature. However, an opaque whitish film was formed in the case of 3Ph-C6. Poly(methyl methacrylate) (PMMA) films containing 2 wt % 3Ph-C3 and 3Ph-C6 were prepared by casting their chloroform solutions onto glass substrates overnight at room temperature. The static water contact angle measurements and XPS analysis for the castings film containing 3Ph-C3 and 3Ph-C6 suggested that degree of the segregation amount of 3Ph-C3 was larger than that of 3Ph-C6. The shorter linker length in the phenyl-substituted star-shaped POSS derivative, 3Ph-C3, with its greater predicted solubility in PMMA, exhibited entropy-driven surface segregation.

Application of silicone nanofilaments coatings towards point-of-use drinking water treatment: Assessment on trace Lead ions, dyes and oils removal

A new coating-based approach for water treatment was demonstrated using silicone nanofilaments (SNF) coatings. In view of some existing point-of-use (POU)/point-of-entry (POE) water treatment systems, where membranes or filters are used to build devices that allow individuals to treat water on their own at the point of consumption. The reported coating-based approach offers an advantage as contaminated water was treated upon contact with the functionalized SNF-coated surfaces, without additional pressure or energy requirement. Besides, the coatings took the shapes of the substrates and demonstrated some different formats can be potentially deployed for POU devices. To illustrate the suggested approach, glass substrates of three different shapes (flat microscopic slides, walls of vials, and three-dimensional (3D) filter frits) were employed. Substrates were readily coated with SNF under ambient conditions via gas phase deposition based on the previous developed protocol, subsequently modified with (3-Mercaptopropyl)triethoxysilane (MPTES), and were used to treat 200 ppb of trace lead ions in water. Results suggested that the coatings as a facile mean to render surfaces/containers functional towards trace lead removal, and enhanced performance compared to their non-coated counterparts.In addition, the oil sorption capacities of the coated frits were also evaluated. By rendering the as-prepared frits amphiphilic, they were used to treat trace lead, water-soluble methylene blue, and oil-soluble Oil Red O dyes. Overall, the study demonstrated and evaluated the use of the SNF coatings by treating some model contaminants in different formats than the existing approaches. The ease of preparation and the flexibility of the approach presented provide opportunities for the design of new water treatment systems and more accessible POU/POE devices.

Revolutionizing scandium detection in real samples: Unleashing the power of sol-gel-based optical sensor.

The development of a highly selective and ultra-sensitive optical sensor for detecting scandium (Sc3+) ions involves incorporating the reagent 2,3-dichloro-6-(3-carboxy-2-hydroxy-1-naphthylazo)quinoxaline (DCHNAQ) into a silica sol-gel thin film on a glass substrate. This innovative approach utilizes tetraethoxy-silane (TEOS) as the precursor, maintaining a sol-gel pH level of 4.5, a water-to-alkoxide ratio of 5:1, and a DCHNAQ concentration of 5.0 × 10-4M. A detailed exploration of the impact of sol-gel parameters on the sensing capabilities of the developed sensor has been meticulously undertaken. This innovative sensor demonstrates remarkable selectivity in evaluating Sc3+ ions over a dynamic range of 7.5-170ng/mL, with limits of quantification and detection recorded at 7.3 and 2.20ng/mL, respectively. Consistent results are achieved with a minimal RSD of 1.47 and 0.94% for Sc3+ ions at 50 and 100ng/mL, respectively, coupled with a swift response time of three min. Assessments of interference demonstrate a noteworthy preference for Sc3+ions, accomplished by enclosing DCHNAQ within the sol-gel framework and making optimal structural modifications to the doped sol-gel. The sensor offers straightforward regeneration using a 0.25M EDTA solution, exhibiting complete reversibility. Comparative analysis with other methodologies underscores the efficacy in determining Sc3+ions in various reference materials, including plant leaves, fish, water, alloys, ores, and monazite samples.

Formation of partially embedded Au nanostructures: Ion beam irradiation on thin film.

The Au partially embedded nanostructure (PEN) is synthesized by ion irradiation on an Au thin film deposited on a glass substrate using a 50 keV Ar ion. Scanning electron microscopy results show ion beam-induced restructuring from irregularly shaped nanostructures (NSs) to spherical Au NSs, and further ion irradiation leads to the formation of well-separated spherical nanoparticles. Higuchi's algorithm of surface analysis is utilized to find the evolution of surface morphology with ion irradiation in terms of the Hurst exponent and fractal dimension. The Au PEN is evidenced by Rutherford backscattering spectrometry and optical studies. Also, the depth of the mechanism behind synthesized PEN is explained on the basis of theoretical simulations, namely, a unified thermal spike and a Monte Carlo simulation consisting of dynamic compositional changes (TRIDYN). Another set of plasmonic NSs was formed on the surface by thermal annealing of the Au film on the substrate. Glucose sensing has been studied on the two types of plasmonic layers: nanoparticles on the surface and PEN. The results reveal the sensing responses of both types of plasmonic layers. However, PEN retains its plasmonic behavior as the NSs are still present after washing with water, which demonstrates the potential for reusability. RESEARCH HIGHLIGHTS: Synthesis of PENs by ion irradiation Utilization of Higuchi's algorithm to explore the surface morphology. Unified thermal spike and TRIDYN simulations being used to explain the results. Glucose is only used as a test case for reusability of substrate.

Drop‐on‐Demand Electrohydrodynamic Printing of Nematic Liquid Crystals

In this paper, electrohydrodynamic (EHD) printing of nematic liquid crystals (LCs) is demonstrated. Miniscule LC droplets, as small as 1 micron, are generated with the EHD printing system and deposited with high precision onto a glass substrate. Herein, we investigate how the voltage waveform and pulse frequency applied to the print nozzle influences the dynamics of the deposition process and the final landed footprint diameter of the printed spherical‐cap‐shaped LC droplets at the glass substrate. To complement results from high‐speed shadowgraphy imaging, simulations were employed to model the jetting process and the formation of the Taylor Cone. Using EHD printing, we show results for two different printing modes: cone‐jetting and micro‐dripping. We highlight the benefits and drawbacks of each mode and conclude with the demonstration of a printed alphanumeric pattern that showcases the capability of EHD printing to deposit very small volumes of nematic LC in order to form well‐defined spatial patterns.This article is protected by copyright. All rights reserved.

Physical and sensing characterization of nanostructured Ag doped TiO2 thin films

Physical and sensing characterization of nanostructured Ag doped TiO2 thin films

Effect of Boron-doping and annealing on the structure, morphological and optical properties of ZnO films prepared by spray pyrolysis method

Abstract Investigations have been conducted into the structure, morphology, thickness, and optical properties of ZnO thin film upon doping it with Boron from boric acid (H3BO3) at a constant concentration and annealing it at various temperatures (200, 300, and 400 °C). The thin films were formed on glass substrates using the spray pyrolysis process at 250°C, and they were then annealed for two hours in air at various temperatures. It was discovered that the annealing temperature and boron doping had a substantial impact on all properties of the ZnO nanostructure. The polycrystalline hexagonal wurtzite structure is present in both ZnO and BZO thin films. With high optical transmission (≥70%), crystallite diameters of 25.8 to 28.5 nm for ZnO and 15.96 to 24.80 nm for BZO, respectively, and significant absorbance up to 400 nm at the maximum annealing temperature (400 °C) for both films. Moreover, the as-deposited and annealed BZO films had optical band gaps of 3.04 eV and 2.9 eV, respectively, which are less than the ZnO film's 3.23 eV band gap; in general, as the annealing temperature increased it decreased.

Analysis of vibrational dynamics in cell-substrate interactions using nanopipette electrochemical sensors

Cell-substrate interaction plays a critical role in determining the mechanical status of living cell membrane. Changes of substrate surface properties can significantly alter the cell mechanical microenvironment, leading to mechanical changes of cell membrane. However, it is still difficult to accurately quantify the influence of the substrate surface properties on the mechanical status of living cell membrane without damage. This study addresses the challenge by using an electrochemical sensor made from an ultrasmall quartz nanopipette. With the tip diameter less than 100 nm, the nanopipette-based sensor achieves highly sensitive, noninvasive and label-free monitoring of the mechanical status of single living cells by collecting stable cyclic membrane oscillatory signals from continuous current versus time traces. The electrochemical signals collected from PC12 cells cultured on three different substrates (bare ITO (indium tin oxides) glass, hydroxyl modified ITO glass, amino modified ITO glass) indicate that the microenvironment more favorable for cell adhesion can increase the membrane stiffness. This work provides a label-free electrochemical approach to accurately quantify the mechanical status of single living cells in real-time, which may help to better understand the relationship between the cell membrane and the extra cellular matrix.

Rapid Fabrication of Large-Grain Opal Films and Photonic Crystal Hydrogel Sensors by a Filter Paper-Enhanced Evaporation Chip.

Developing a rapid fabrication method for crack-free opal films is a significant challenge with broad applications. We developed a microfluidic platform known as the "filter paper-enhanced evaporation microfluidic chip" (FPEE-chip) for the fabrication of photonic crystal and inverse opal hydrogel (IOPH) films. The chip featured a thin channel formed by bonding double-sided adhesive poly(ethylene terephthalate) with a polymethyl methacrylate cover and a glass substrate. This channel was then filled with nanosphere colloids. The water was guided to evaporate rapidly at the surface of the filter paper, allowing the nanospheres to self-assemble and accumulate within the channel under capillary forces. Experimental results confirmed that the self-assembly method based on the FPEE-chip was a rapid platform for producing high-quality opal, with centimeter-sized opal films achievable in less than an hour. Furthermore, the filter paper altered the stress release mechanism of the opal films during drying, resulting in fewer cracks. This platform was proven capable of producing large-grain, crack-free opal films of up to 30 mm2 in size. We also fabricated crack-free IOPH pH sensors that exhibited color and size responsiveness to pH changes. The coefficient of variation of the gray color distribution for crack-free IOPH ranged from 0.03 to 0.07, which was lower than that of cracked IOPH (ranging from 0.07 to 0.14). Additionally, the grayscale peak value in 1 mm2 of the crack-free IOPH was more than twice that of the cracked IOPH at the same pH. The FPEE-chip demonstrated potential as a candidate for developing vision sensors.

Shaping an evanescent focus of light for high spatial resolution optogenetic activations in live cells

Confining light illumination in the three dimensions of space is a challenge for various applications. Among these, optogenetic methods developed for live experiments in cell biology would benefit from such a localized illumination as it would improve the spatial resolution of diffusive photosensitive proteins leading to spatially constrained biological responses in specific subcellular organelles. Here, we describe a method to create and move a focused evanescent spot, at the interface between a glass substrate and an aqueous sample, across the field of view of a high numerical aperture microscope objective, using a digital micro-mirror device (DMD). We show that, after correcting the optical aberrations, light is confined within a spot of sub-micron lateral size and ∼100 nm axial depth above the coverslip, resulting in a volume of illumination drastically smaller than the one generated by a standard propagative focus. This evanescent focus is sufficient to induce a more intense and localized recruitment compared to a propagative focus on the optogenetic system CRY2-CIBN, improving the resolution of its pattern of activation.