Indium-doped Tin Oxide Substrates Research Articles

A novel strategy towards the fabrication of highly stable and sensitive non-enzymatic glucose sensor based on Ni3N thin films using high power impulse magnetron sputtering

Glucose level surveillance in mankind is considered the greatest need of recent times to achieve healthy lifestyle goals due to its health-related concern for humans. To fulfill the need, Nickel-based compounds emerge with excellent bio-mimic properties. However, due to the poor electrical properties of oxides and hydroxides of Ni, developing a supporting base that can enhance electron transportation is mandatory. The present work is dedicated to non-enzymatic glucose detection by electrochemical means on the Ni3N thin film on an Indium-doped Tin Oxide (ITO) substrate as a working electrode in an alkaline medium. The Ni3N films use HiPIMS as a deposition technique due to its high ionization rate of sputtered species and dense plasma which helps the Ni ions to react with nitrogen in the formation of a perfect Ni3N phase, and it is a green process that can contribute to sustainable manufacturing. Ni3N thin film deposited at a 60 % N2 flow ratio shows the largest crystallinity and catalytic properties, which helps this modified electrode to have significant potential for glucose detection. The Ni3N modified electrode acquires a lower linear range of 0.001–1.25 mM with sensitivity and Limit of Detection (LOD) of 337.46 µAmM–1cm−2, and 0.78 µM, respectively, and a higher linear range of 1.25–7.3161 mM with a sensitivity of 158.58 µAmM–1cm−2. The amperometric measurements reveal the fast response of the electrode towards glucose detection at 2.46 secs. The key measures of the electrode according to the corresponding measurements are satisfactory selectivity, reproducibility, repeatability, and operational stability. The modified electrode shows a significant response for real samples such as commercially available honey, apple juice, and biological fluids.

Influence of deposition potential and substrate characteristics on the photovoltaic conversion efficiency of p-SnS absorbing layers

In this study, thin films of tin sulfide (SnS) deposited on indium-doped tin oxide (ITO) and fluorine-doped tin oxide (FTO) substrates using Sn-S electrodeposition were systematically investigated. Notably, a novel non-toxic sulfur precursor was employed, emphasizing its role in ensuring the safety and environmental friendliness of the synthesis process. The research was focused on the influence of deposition potential and substrate type on the physical properties of SnS films. X-ray diffraction (XRD) analysis disclosed distinct peaks corresponding to orthorhombic SnS phase planes (101), (111), and (040). Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX) revealed a uniform distribution of essential components, particularly notable at −0.7 V on ITO and −0.9 V on FTO substrates. Raman spectroscopy identified characteristic peaks at 90 cm−1 and 222 cm−1. UV–visible spectrophotometry highlighted alterations in the optical band gap of SnS films on ITO (1.93 eV to 1.57 eV) and FTO (2.13 eV to 1.98 eV). Mott-Schottky analysis revealed consistent p-type conductivity behavior in the SnS layer, while both ITO and FTO layers exhibited n-type conductivity behavior. This characterization underscores the distinct electronic properties of each layer, providing valuable insights for the development of advanced optoelectronic devices. Electrochemical Impedance Spectroscopy (EIS) results demonstrated a significant reduction in charge transfer resistance (Rct) of SnS films on ITO at −0.7 V. The solar cell efficiency of the SnS absorber layer reached 2.2% on ITO at −0.7 V, contrasting with 1.47% on FTO at −0.9 V.

Synthesis of Co3O4 electrodes by electrochemical deposition for water splitting reaction

Introduction: The use of Ni foam substrates for the growth of catalysts is a common practice in electrochemical water splitting reactions, although their stability in some electrolytes can be problematic, hindering the scalability of synthesis. This study aims to explore alternative substrates for catalyst growth, focusing on cobalt oxide (Co3O4) due to its potential in enhancing electrochemical water splitting efficiency. Methods: Cobalt oxide (Co3O4) was synthesized on various conductive substrates including fluorine-doped tin oxide (FTO), indium-doped tin oxide (ITO), and carbon cloth (CC), employing electrochemical deposition techniques. The morphological and crystalline properties of the Co3O4 coatings on these substrates were characterized and analyzed to understand their influence on the catalyst's performance in water splitting reactions. Results: The electrochemical deposition resulted in a more condensed coverage of Co3O4 on the CC substrate, attributed to the crystal's oriented aggregation. The crystallization and lattice development of Co3O4 varied significantly across different substrates, exhibiting high crystallization on FTO and ITO substrates but poorer crystallization on the CC substrate. Notably, the Co3O4/CC electrode demonstrated superior performance in hydrogen evolution reaction, achieving the lowest overpotential of -382 mV at a current density of 10 mA cm-2. Conclusion: The findings suggest that carbon cloth (CC) presents a promising alternative to Ni foam substrates for the growth of Co3O4 catalysts in electrochemical water splitting applications. The enhanced performance of Co3O4/CC electrodes, particularly in terms of overpotential and crystallization behavior, highlights the potential of using CC substrates to improve the efficiency and scalability of water splitting reactions for sustainable hydrogen production.

Enhancing UV Stability of Perovskite Solar Cells with Transparent Fluorinated Polyimide

Ultraviolet (UV)-induced degradation is one of the major problems in the field of perovskite solar cells (PSCs). Therefore, exploring materials and techniques to prevent UV light from penetrating into the device is urgently necessary. Here, we developed a special transparent fluorinated polyimide (FPI) resin, which can be directly spin-coated on the front side of conventional indium-doped tin oxide substrates (glass/ITO). Most aromatic polyimides strongly absorb visible light and are colored. The FPI we designed and synthesized bears electron-acceptor CF 3 - groups, which reduces the intra-/intermolecular charge-transfer (CT) effect, enabling FPI to possess high transmittance in the visible range while completely blocking UV light. As a result, the FPI coating slightly pulls down the initial power conversion efficiency (PCE) (21.02% to 20.19%). Remarkably, the coating significantly improves the PSC UV stability. Upon an 8-h enhanced UV aging test in air, the FPI/glass/ITO-based PSC is able to retain 85.0% of its initial PCE. In contrast, the control device (glass/ITO-based PSC) only keeps 40.9% of its initial PCE. The protective effect of FPI is even more prominent in current popular 3D/2D high-performance PSCs because UV light can seriously damage the 2D layer. The unencapsulated 3D/2D device based on FPI/glass/ITO substrate has a very high PCE retention of up to 80% after 12-h enhanced UV aging test in air, comparing to 36% for the control 3D/2D device without FPI. This work demonstrates that FPI and its possible derivatives could provide a feasible avenue to handle UV-induced degradation for PSCs effectively.

Efficient laboratory perovskite solar cell recycling with a one-step chemical treatment and recovery of ITO-coated glass substrates

The proliferation of organic–inorganic perovskite solar cells (PSCs) has garnered considerable attention due to their potential for low-cost, large-scale photovoltaic panel production. However, the inclusion of lead in PSCs poses significant sustainability challenges, necessitating effective end-of-life treatment strategies to mitigate environmental pollution and comply with electronic waste disposal regulations. In this study, we present a novel recycling system for decomposing and reclaiming the constituent materials of a typical PSC. Utilizing a one-step solution process extraction approach, we successfully preserved the chemical composition of each layer, enabling their potential reuse. This recycling method not only addresses the separation of the toxic lead component but also emphasizes the recovery of other valuable PSC layers. Notably, the commonly used hole transport layer in perovskite solar cells is Spiro-OMeTAD, which was successfully extracted with chlorobenzene, with its purity subsequently confirmed. Moreover, the removal of individual layers facilitated the retrieval of indium-doped tin oxide (ITO) conductive glass, a critical substrate in PSC fabrication. Comparative analysis of the physical and electrical properties of recycled and reference ITO substrates revealed minimal discrepancies, indicating the feasibility of reusing recycled substrates without compromising device performance. The proposed recycling technique offers a practical approach to mitigate pollution risks, minimize waste generation during the recycling process of perovskite-based solar cells, and reduce end-of-life recycling costs.

Molybdenum-doped BiVO4 thin films: Facile preparation via hot-spin coating method and the relationship between surface statistical parameters and photoelectrochemical activity

Molybdenum-doped BiVO4 thin films were uniformly coated on indium-doped tin oxide (ITO) substrates via a facile modified hot spin coating (HSC) technique. The prepared layers were used as photoanode in a photoelectrochemical (PEC) cell. Different percentage of Mo dopant was examined to maximize the photo-current density (J) of the layers. The highest J value (872 ± 8 μA/cm2) was obtained by 5 atomic% of Mo doping. After that, the surface topographies of these samples were changed by varying the initial precursor concentration from 27 to 80 mM. The relation between surface topographies and the PEC activity of Mo-doped BiVO4 thin films was investigated from microscopic point of view by calculating the surface roughness exponent of α, and a mechanism for the PEC activity of Mo-doped BiVO4 photoanodes was proposed accordingly. The sample with a small roughness exponent provided a surface with jagged microscopic fluctuations which may trap the air molecules between the electrolyte and sample surface, hindering the fine atomic interaction for photo-generated electron-hole transition. Therefore, the layer with the highest roughness exponent (2α = 0.48 ± 0.03), which means the smoother microscopic surface and better interfacial contact with the electrolyte, exhibited the best PEC activity.

Effect of RF-sputtering temperature of ITO electrodes on the resistive switching behaviour of ITO/RbPbI3/Cu devices

In this work, we deposit Indium doped Tin Oxide (ITO) on a glass substrate using the Radio-Frequency Sputtering technique at different temperatures and studied its structural and optical properties. Various structural, optical, and morphological studies are conducted on the ITO substrates. In addition, we have used these ITO films as conducting electrodes in MIM (metal-insulator-metal) type structures for resistive memory application. A resistive switching memory device based on RbPbI3 with sputtered ITO films as the bottom electrode is fabricated and studied for its electrical performance. It has been found that the device showed the write-once-read-many (WORM) nature at a sputtering temperature of 300 °C with a good OFF/ON ratio. The devices with ITO film sputtered a temperature below 300 °C do not show any switching behavior due to lower conductivity and improper surface morphology.

Developing a Simple, Effective, and Quick Process to Make Silver Nanowires with a High Aspect Ratio.

A growing number of people are interested in using silver nanowires (AgNWs) as potential transparent and conductive materials. The production of high-performance and high-throughput AgNWs was successfully optimized in this work using a one-step, straightforward, and reproducible modified polyol approach. The factors influencing the morphology of the silver nanowires have undergone extensive research in order to determine the best-optimized approach for producing AgNWs. The best AgNW morphology, with a length of more than 50 m and a diameter of less than 35 nm (aspect ratio is higher than 1700), was discovered to be produced by a mixture of 44 mM AgNO3, 134 mM polyvinylpyrrolidone (PVP) (Mo.Wt 40,000), and 2.4 mM KCl at 160 °C with a stirring rate of 100 rpm. With our improved approach, the overall reaction time was cut from almost an hour with the conventional polyol method to a few minutes. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and ultraviolet (UV) spectroscopy were used to characterize AgNWs. The resultant AgNWs' dispersion was cleaned using a centrifuge multiple times before being deposited on glass and PET substrates at room temperature. In comparison to commercial, delicate, and pricey indium-doped tin oxide (ITO) substrates, the coated samples displayed exceptionally good sheet resistance of 17.05/sq and optical haze lower than 2.5%. Conclusions: Using a simple one-step modified polyol approach, we were able to produce reproducible thin sheets of AgNWs that made excellent, flexible transparent electrodes.

Effect of In-doping on electrochromic behavior of NiO thin films

Undoped and Indium doped Nickel Oxide (NiO) thin layers with different doping content (2, 4, 6 at.%) were successfully deposited on glass and Indium-doped Tin Oxide (ITO) substrates using spray pyrolysis (SP) technique. The effect of indium on the microstructural, morphological, optical, and electrochromic behaviors of NiO films was investigated by X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy coupled with Energy Dispersive X-ray Spectroscopy, UV–Vis-NIR spectrophotometry. XRD examination shows that all NiO layers have a polycrystalline cubic phase with a preferred orientation along the (111) plane. Raman spectroscopy proves the XRD result. SEM images show nanograins formation in all the sprayed films. The EDS analysis and the elemental mapping reveal the homogeneous distribution of the elements. The optical analysis reveals an average transmission of about 72% in the visible light region and an optical band gap energy of 3.54 eV for the undoped sample. These values decreased with increasing Indium content to reach 65% and 3.46 eV, respectively for the 6 at.% In-doped sample. The electrochromic behavior of NiO films deposited on ITO substrates was measured by cyclic voltammetry in a 2 M KOH aqueous electrolyte. The results show that a specific capacitance of 66 F. g − 1 at 5 mV.s − 1, an optical density variation of 43%, and a coloration efficiency of 93.74 cm2/C were obtained for 2 at.% In doped NiO. These values are considerably higher than those obtained for the undoped films, indicating that the In doping improved the electrochromic performance of nickel oxide films.

Highly efficient ultraviolet photodetector based on molybdenum-doped nanostructured NiO/ITO thin film

Nanostructured pure and molybdenum (Mo)-doped nickel oxide (NiO) thin films with various concentrations of Mo dopants were successfully sputtered on indium-doped tin oxide (ITO) substrates to apply in the ultraviolet (UV) photodetector sensors. The influence of Mo concentration on the thin films' structural, morphological, and optical properties was studied using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) equipped with energy-dispersive X-ray, and UV–Vis spectrophotometer. The XRD studies confirm that all the prepared films are polycrystalline and possess a cubic phase structure. The FE-SEM images suggest that the distribution of the prepared samples on the substrate is homogeneous and free from any cracks. Spectrophotometry studies reveal the decrement of the optical band gap with the increase of Mo concentration in NiO thin films. All thin-film current–voltage curves measured under dark conditions and UV illumination of 390 nm showed Ohmic contacts. A noticeable improvement in the responsivity and external quantum efficiency (EQE) with the increased Mo concentration was detected. The metal–semiconductor–metal (MSM) employed in NiO thin films showed maximum responsivity and EQE of 539 mA/W and 171.4% at 390 nm, respectively, for the sample with 1.73 at% Mo doping.

Prickly Pear Fruit Extract: Capping Agent for the Sol–Gel Synthesis of Discrete Titanium Dioxide Nanoparticles and Sensitizer for Dye-Sensitized Solar Cell

Plant extracts have been utilized as an ecofriendly natural reducing agent for the synthesis of nanomaterials, including metal oxides. Prickly pear (opuntia) fruit extract (PPE) was used as a reducing agent for the sol–gel synthesis of titanium dioxide nanoparticles (TiO2 NPs) and as a sensitizer for the TiO2 NPs photoanode used in dye-sensitized solar cells (DSSCs). Ultraviolet-visible and infrared spectra, X-ray diffraction patterns, and scanning electron microscopic images were confirmed in the formation of semiconducting TiO2 NPs with the predominate size of ~300 nm. The use of PPE rendered discrete TiO2 NPs, whereas the typical synthesis without PPE resulted TiO2 aggregates. TiO2 NPs had a tetragonal crystalline structure, and their grain size was varied with respect to the concentration of PPE. The size of TiO2 crystallites was found to be 20, 19, 15, and 10 nm when the volume percentage of PPE was 0.2, 0.4, 0.6, and 0.8%, respectively. TiO2 NPs obtained using PPE were coated on indium-doped tin oxide substrates and sensitized with natural dye made up of PPE and synthetic dyes, namely rose Bengal (RB) and eosin yellow (EY). The photoanode fabricated with dye-sensitized TiO2 NPs was subjected to current–voltage response studies. The maximum power-conversion efficiency, 1.4%, was recorded for photoanodes sensitized with PPE dye, which is considerably higher than that for RB (1.16%) or EY (0.8%). Overall, the above findings proved that PPE can be used as a potential reducing/capping agent and TiO2 sensitizer for DSSC applications.

Piezoionic transfer effect in topological borophene-bismuthene derivative micro-leaves for robust supercapacitive electronic skins

To gain high performance in electrochemical device, exquisite accelerating ion-electron transfer is an effective way. Here, a topological idea is realized to design a micro-leave electrode by patterning borophene-bismuthene derivative. The inner bismuthene offers high conductive skeleton, intermediate BiOCl and Bi2O3 derivative as ornament contribute to supercapacitive property, and the outer borophene layer not only boosts supercapacitive property, but also reserves the topological shape. Assisted by a hydrogel electrolyte on a flexible indium-doped tin oxide substrate, a robust pressure sensor is fabricated, in which a piezoionic transfer effect is demonstrated to induce fast ions extraction and migration kinetics among the topological micro-leaves. Then the specific capacitance of electrode increases by 2.483 times comparing with the micro-leaves without borophene. The resultant robust electronic skin sensor presents a comparable sensitivity of 1.60 kPa−1 in the tiny pressure range of ≈ 50–150 Pa, and sensitivity of 1.01 kPa−1 in 150 Pa-8.5 kPa, low detection limit as 0.59 Pa, fast response/recovery time (80/80 ms), wide detection range (∼220 kPa) and reliable capacitance retention of 97.92% even after 10000 cycles. This has been successfully used to monitor the physiological signals and illustrates potential application prospects in human-computer interaction.

Composite Assembling of Oxide-Based Optically Transparent Electrodes for High-Performance Asymmetric Supercapacitors.

Simultaneously achieving a transparent and high-energy density supercapacitor is a major challenge because of the trade-off between energy storage capacity and optical transparency of active electrode materials. Herein, we demonstrate a novel approach to construct an optically transparent asymmetric supercapacitor (Trans-ASC) by assembling positive (ZnO-SnO2) and negative (TiO2-SnO2) composite thin-film electrodes on a conductive indium-doped tin oxide substrate via reactive DC magnetron cosputtering. The optical transmittance for both composite thin films is found to be 68% (ZnO-SnO2) and 64% (TiO2-SnO2). Furthermore, electrochemical kinematics of the primed transparent electrodes are scrutinized in 0.5 M KOH electrolyte without affecting the transparency of active electrodes. The structural reliability of the electrodes aids the superb electrochemical performance to construct a Trans-ASC, TiO2-SnO2//ZnO-SnO2, which works at a voltage of +1.2 V and attains a higher areal capacitance of 44.6 mF cm-2 at 2 mA cm-2. The assembled Trans-ASC delivers a maximum areal energy density of 8.75 μW h cm-2 with an optimal areal power density of 570 μW cm-2. Additionally, the capacitance retention of 81.6% and transparency of both electrodes remain almost the same (up to 60% for ZnO-SnO2 and 62% for TiO2-SnO2) even after 10,000 charging-discharging cycles. These remarkable electrochemical properties and outstanding cycling stability of the designed Trans-ASC device make it a potential candidate for storing energy and for further use in transparent electronic devices.

Effect of indium doping on the structural, optical and electrochemical behaviors of CeO2 nanocrystalline thin films

Undoped and indium (In) doped cerium oxide (CeO2) nanocrystals (NCs) have been successfully synthesized onto glass and glass coated indium-doped tin oxide (ITO) substrates under optimized conditions via spray pyrolysis at 450 °C, with simultaneous insertion of In at different percentages (0, 2, 4, 6, 8 at. %) as a dopant. Several techniques for characterization were utilized to investigate the indium effect on the microstructural, optical, morphological and electrochemical properties of the CeO2 material. The as-prepared samples show well-defined face centered cubic fluorite structure grown along [200]. Raman spectroscopy was used to investigate the imperfections where longitudinal optical mode confirmed the existence of imperfections in the form of oxygen vacancies. Peak asymmetry and width of Raman active mode are ascribed to the presence of Ce3+ ions and oxygen vacancies, which was affected by the insertion of In3+ ions in the CeO2 nanocrystals. Scanning electron microscopy (SEM) images showed that the morphologies of the samples was influenced by indium incorporation. The optical properties result via transmittance and absorbance analysis within the UV–Vis–NIR domain exhibited that the samples are highly transparent (78–83%). The obtained band gap energy (Eg) depends on the percentages of the In dopant. The results of cyclic voltammetry (CV) show that In addition helps to enhance the ion storage capacities (ISC) of CeO2 material. The CeO2 doped thin films remained completely transparent after the insertion/extraction of Li+ ions. These important results widen the field of application of this oxide, particularly for electrochromic devices.

Nucleation/Growth and Optical Proprieties of Co-doped ZnO Electrodeposited on ITO Substrate

A Co-doped ZnO layer was prepared by electrodeposition method on indium doped tin oxide (ITO) substrate using a cathodic reduction from nitrate medium with different doping percentages of cobalt. The bath temperature was controlled at 70 °C. The films were cathodically electrodeposited in a bath containing 5 mM Zn(NO3)2. 6H2O, while the source of Co is Co(NO3)2.6H2O where 0.1M KNO3 was used as supporting electrolyte. The nucleation and growth mechanism of Co-doped ZnO nuclei have been studied by cyclic voltammetry and chronoamperometry. The cyclic voltammetry shows that the electrodeposition of ZnO and Co-doped ZnO at a negative potential around -1.0 V versus saturated calomel electrode (SCE) is a quasi-reversible reaction controlled by the diffusion process. Comparing current transients curves obtained by the chronoamperometric method with the theoretical curves of current density j versus t ½ allows us to say that the nucleation is 3D instantaneous, as shown in SEM analysis. The presence of Co does not modify the nucleation and growth mechanism. The XRD patterns show that the substitution of zinc by cobalt does not change the würtzite crystal structure, but the crystallite size decreases with the cobalt percentage. The transmittance spectra indicate that the Co-doped ZnO films are transparent in the visible range. The optical gap increases with the doping percentage of cobalt.

Probing Individual Cuprous Oxide Microcrystals towards Carbon Dioxide Reduction by using In Situ Raman‐coupled Scanning Electrochemical Microscopy

AbstractIn this work, the simultaneous investigation of a single cuprous oxide microcrystal towards CO2 electroreduction (CRR, CO2 reduction reaction) by using Raman microscopy and scanning electrochemical microscopy (SECM) is shown. Cu2O microcrystals were electrochemically crystallized on an indium‐doped tin oxide‐substrate (ITO). Structural changes of the Cu2O microcrystal are observed in situ by Raman microcopy, which indicates their fast conversion into elemental Cu at low overpotentials. Simultaneously, detection of products of the CO2 reduction is carried out electrochemically using the sample‐generation tip‐collection mode (SG/TC) of SECM and formate ions are the main product of CRR, as detected by a 10 μm Pt ultramicroelectrode (UME). Thus, with our approach, the very beginning of the CRR (onset potential), potential‐dependent product formation as well as structural changes in the catalyst can be precisely investigated.

Role of electrolyte concentration on growth kinetics, film thickness, structural, compositional and optical properties of cadmoselite thin films through electrochemical route

For the past few decades Cadmium chalcogenides attracted many researchers due to its interesting band gap nature, structure, electrical, optical and photoelectrochemical properties. The objective of the present work is to determine the modified features of cadmoselite thin film gown by simple, low cost, low temperature electrodeposition technique. Cadmoselite thin films were deposited on Indium doped Tin Oxide substrate. X-ray diffraction results reported that the deposited films were found to be polycrystalline nature with hexagonal structure. The structural parameters viz., crystallite size, rms microstrain, dislocation density and stacking fault probability were determined for the deposited films. Surface morphology along with film composition reported that the deposited films have smooth surfaces with well defined stoichiometry. Optical properties such as transmittance, absorbance and reflectance measurements showed that the deposited films found to exhibit maximum absorbance from the violet to blue region. The band gap value of the deposited films is found to be 1.76 eV. The parameters such as refractive index, extinction coefficient, optical conductivity, real and imaginary dielectric constants were estimated.

Communication—Preparation of a Porous β-Cu3V2O8 Film for Photoelectrochemical Water Oxidation

The combination of narrow band gaps and notable stabilities against photoelectrochemical corrosion brings copper vanadates into the forefront of emerging photoanodes. Herein, we report a feasible approach to fabricate β-Cu3V2O8 thin film with a porous structure directly on indium-doped tin oxide (ITO) substrate for photoelectrochemical water oxidation. The porous β-Cu3V2O8 photoanode exhibits a photocurrent density of 220 μA cm−2 at 1.55 V vs RHE (reversible hydrogen electrode) in pH 9.2 borate buffer electrolyte under simulated solar irradiation. The present work could provide a base for further development of porous β-Cu3V2O8 as a solar fuels photoanode.

Fast-switching electrochromic response of WO3 · 2H2O of plate-like particles synthesized by liquid phase deposition

WO3 · 2H2O with the layered crystal structure was grown into films consisting of plate-like particles on indium doped tin oxide substrates by the liquid phase deposition at room temperature. The [WOF5]- complex was prepared by dissolving 0.015 mol tungstic acid in 86 cc of a 2.34 wt% hydrofluoric acid solution. The hydrolysis of [WOF5]- species in the presence of boric acid at room temperature was studied by 19F NMR spectroscopy to gain insight into the formation mechanism of WO3 · 2H2O. Microstructural studies revealed that the plate-like particles are single crystals with well-developed facets in octagonal shapes. The basal plane of the plate-like particles is parallel to the corner-sharing WO6 octahedra layers. The films showed a 92.7 ± 7.5 cm2/C coloration efficiency and fast response electrochromic properties with a bleaching time and a coloration time of 0.6 s and 2.0 s, respectively. Such a fast electrochromic response was attributed to the facile migration of proton ions through the layered crystal structure of WO3 · 2H2O and the plate-like morphology of the films.

Effect of transparent conducting substrates on the structure and optical properties of tin (II) oxide (SnO) thin films: Comparative study

Tin (II) oxide (SnO) thin films were deposited onto indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO) and glass substrates using the thermal evaporation technique. The X-ray diffraction (XRD) patterns revealed that the evaporated SnO film was an amorphous structure. The shape and size distributions of surface grains for SnO/ITO, SnO/FTO, and SnO/glass were investigated using atomic force microscopy (AFM). The purity of the SnO onto ITO, FTO, and glass substrates was confirmed using Raman spectra. Tauc's relation for SnO/ITO, SnO/FTO, and SnO/glass thin films indicated the occurrence of direct transitions. The redshift of the EgOpt correlated with the grown of SnO nanoparticles. The electronic polarizability, dielectric constants, energy loss functions, and optical conductivity constants were directly derived from the extinction coefficient (k), and refractive index (n). In addition, the nonlinear susceptibilityχ(3), non-linear refractive index n(2) and nonlinear absorption coefficient (βc) were valued based on the semi-empirical relation for SnO/ITO, SnO/FTO, and SnO/glass. The SnO/ITO films displayed higher nonlinear parameters than SnO/FTO films. Therefore, SnO/ITO will be a promising optical system in the nonlinear optics field.