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Electrochromic pseudocapacitive transition-metal oxide materials, such as tungsten oxide, which combine fast response, high energy density, and optical effects, can play a significant role as energy storage materials. Here we investigate the electrochemical kinetics of thin films of tungsten oxide, which turn transparent to sky-blue color in the lithiated state due to the reduction of W6+ to W5+. We investigated the charge density, charge transfer, ion diffusion, and interfacial behavior upon Li+ insertion/de-insertion in WO3. The electrochromic thin film’s pseudocapacitive and electrical double layer mechanism was differentiated based on the power-law. Faradaic diffusion-controlled process dominates over the surface capacitive behavior at scan rates below 40 mV s−1 . These films exhibit an areal charge density of around 100 mC cm−2 and a capacitance of 80 mF cm−2, superior to most comparable electrochromic materials and supercapacitors. This work combines electrochromics and energy storage properties and provides a fundamental understanding of pseudocapacitive and electrochromic mechanisms in WO3. [ABSTRACT FROM AUTHOR]

Carbon nanofoam papers (CNFPs) serve as device-ready negative electrodes for nonaqueous sodium-ion (Na-ion) batteries, with fast and reversible Na+ storage at the aerogel-like, disordered carbon nanofoam. These binder-free, scalable electrode architectures are not only advantageous for the construction of practical, high-performance Na-ion cells, but are also effective platforms to analyze charge-storage mechanisms. We use in situ optical imaging at the outer surfaces of CNFPs in a Na half-cell to track the distinctive color changes that accompany the multi-stage Na+-storage processes on scanning these electrodes through their active voltage window (0–2 V vs Na∣Na+). We observe that electrochromic transitions ― black in the native (unsodiated) state→blue→red/gold ― occur primarily with deep levels of sodiation at <0.5 V vs Na∣Na+. In situ Raman scattering measurements in the same optical cell show that these color changes correlate with shifts in the characteristic G-band Raman peak that would indicate bulk Na+ insertion into nanoscopic graphitic domains within the aerogel-like carbon. The CNFPs also exhibit appreciable Na-ion storage at higher voltage (0.5–2 V vs Na∣Na+), which can be ascribed to surface-based mechanisms that are accompanied by shifts in the D-band Raman peak, but which do not induce appreciable color change [ABSTRACT FROM AUTHOR]

Modulation of reflectance resulting from the change in optical constants in LixCoO2 during lithium de/intercalation is studied and quantified by in-operando and ex situ optical spectroscopy. To this aim, the LiCoO2 (LCO) thin films are sputter deposited using radio-frequency ion-beam sputtering. The films are structurally characterized by X-ray diffraction and transmission electron microscopy. The reversible electrochemical and electrochromic performance is determined by in-operando optical reflectance. Exsitu reflectance, at particular charge states, is used to determine the optical constants by modeling the optical spectrum using the Clausius-Mossotti relation. The model reveals a dominant resonant wavelength at 646 nm for the fully intercalated state of LCO. For the delithiated state or Li0.5CoO2, a much broader and significantly larger absorption peak is obtained by the model description. This significantly broad and intense absorption peak can be associated with the conducting nature of the films upon lithium removal. Furthermore, the observed complex refractive index (CRI), evolving with the lithium content, is justified by the prior reported density of states calculations. With the CRI, the corresponding variation of the real and imaginary part of the dielectric function reveals that the intercalation of lithium and the consequent phase propagation follows a layer-like reaction. [ABSTRACT FROM AUTHOR]

The ultrafast carrier dynamics in SnSe2 film and their influencing factors are studied using femtosecond transient absorption (TA) spectroscopy. Nano-scale SnSe2 sample films are prepared by pulsed laser deposition on the SiO2 substrate. The observed carrier dynamics are influenced by the film thickness and pulse energy. All carrier ultrafast dynamics can be perfectly fitted with a tri-exponential decay model, which means that the carriers have undergone the process of carrier scattering, carrier recombination and diffusion. The influence of the surface reorganization process and the deep defect state in the material makes the carrier lifetime longer in the thicker film. Moreover, the defect state intensifies the state filling effect, leading to the production of bleaching signal in thin thinner film. With the increase of the pump pulse energy, the carrier lifetime becomes longer. This is due to the influence of the pulse energy on the carrier concentration and the temperature difference between the carrier temperature and the lattice temperature. And the influence of pump pulse energy of band gap reconstruction makes the peak in TA spectrum move with the change of pulse energy. The results reveal the carrier dynamics in SnSe2 thin film at different pump pulse energy and identify the critical role of the pump pulse in photo-generated phenomena. [ABSTRACT FROM AUTHOR]

Functional properties of flexible reflective electrochromic composites comprised of polyaniline-coated metallized textile were investigated in this study. Polyaniline was deposited electrochemically onto metal-plated textile fabric and the resulting composites were investigated by electrochemical means as well as by optical-digital colour analysis. Surface morphology and microstructure were evaluated using scanning electron microscopy. Electrochromic performance of the conducting textile and polyaniline composites was optimized by tuning the applied electrochemical switching parameters. Electrochromic textile composites exhibited reversible colour change with good visual contrast between the coloured and bleached states. Functional stability of electrochromic metal-plated textile/polyaniline composite was evaluated by continuous switching between the colored states for 100 cycles. Herein presented concepts might find future use in the development of flexible, colour changing visual interfaces and/or wearable technology, the Internet of things (IoT) devices and optical sensors. [ABSTRACT FROM AUTHOR]

The response of GafchromicTM EBT-XD films to proton irradiation using a Mevion S250TM proton therapy system is studied in this work. Film samples from different batches were irradiated with doses from 0.25 Gy to 20 Gy using a Mevion S250 spread-out Bragg peak (SOBP) clinical proton beam. Using a fiber-coupled optical spectrometer, transmission spectra of the films were acquired over 400–800 nm range (with 2.5 nm resolution). The optical density (OD) of the films was also measured with a flatbed scanner. The characteristics of the film were investigated for dependencies on dose, inter-batch, energy, linear energy transfer (LET), and radiation type. Post-irradiation temporal growth of the OD of the films was also investigated. The net absorbance spectra of EBT-XD films exhibited two absorption peaks located at 636 nm and 585 nm. The measurement of percentage depth dose with the films showed ∼1%–5% and 7%–8% under-estimation on the dose in mid-SOBP and distal SOBP regions, respectively, compared to ionization chamber measurement. No significant energy dependence was noted in the OD of the films when irradiated at the same dose using different proton energies. Approximately 4%–10% drop in spectral response was seen for the proton-irradiated films relative to the films irradiated in photon beams. Temporal growth of the optical density showed a different developing slope between photon and proton irradiation in the first 12 h, but both reached a stable response 24 h after irradiation. [ABSTRACT FROM AUTHOR]

TiO2 nanowires with high transparency and good ion storage capacity were explored as the charge-balancing layers for assembling electrochromic devices (ECDs). Increase thickness of TiO2 nanowires layer lowers the driving potential of the entire ECDs accompanied with reduced potential at the EC layer electrode, which further leads to decreased optical contrast and switching speed of the ECDs. Meanwhile, it can be found that the EC layer electrodes possess larger charge densities than those of TiO2 nanowire electrodes during the electrochemical redox process of these ECDs. However, the intrinsic injection and extraction charge densities of each single electrode are similar, which appears that the intrinsic charge balance of EC layer and TiO2 nanowires electrodes play more important role in the cycling stability of the ECDs. ECD with an optimum thickness of the TiO2 nanowires layer exhibits good electrochromic properties in term of high optical contrast (∼45%), fast switching speed (3.23 s) and excellent cycling stability (which has nearly no decay after 5000 cycles). This study explores the effects of thickness of TiO2 Nanowires layer on electrode potentials and electrochromic properties of electrochromic devices (ECDs), providing a potentially new direction for the preparation of ECDs with good integrated performance. [ABSTRACT FROM AUTHOR]

Raman microscopy is one of the methods that could be used for future post-mortem analyses of samples extracted from ITER plasma facing components. This study shows that this technique is useful for studying tungsten-based materials containing impurities including oxides and nitrides. Here, we apply pulsed laser deposition and DC argon glow discharges to produce tungsten-containing synthetic films (compact, and porous), and nanoparticles, and investigate the influence of their morphology on the measured Raman spectra. The amounts of oxygen and/or nitrogen in the films are also investigated. Comparative data are obtained via x-ray Photoelectron Spectroscopy, Atomic Force Microscopy, Electron Microscopies (Scanning and Transmission), Energy Dispersive x-ray spectroscopy, and Time-of-Flight Elastic Recoil Detection Analysis. The power density of the laser beam used to perform the Raman microscopy is varied by up to 4 orders of magnitude (0.01–20 mW μm−2) so as to investigate the thermal stability of films and nanoparticles. As a first result, we give evidence that Raman microscopy is sensitive enough to detect surface native oxides. Secondly, more tungsten oxides are detected in porous materials and nanoparticles than in compact films, and the intensities of the Raman band correlate to their oxygen content. Thirdly, the thermal stability of these films (i.e. structural and chemical modification under laser heating) is poor when compact films contain a sufficiently large amount of nitrogen. This finding suggests that nitrogen can be substituted by oxygen during Raman laser induced heating occurring in ambient air. Finally, our methodology can be used to rapidly characterize the morphology and chemistry of the samples analyzed, and also to create oxides at the micrometer scale. [ABSTRACT FROM AUTHOR]

Films of electrochromic Ni oxide, with thickness in the ~100–1000-nm range, were prepared by reactive advanced gas deposition (AGD) and, for comparison, also by reactive DC magnetron sputtering (MS). Voltammetric cycling was performed in an electrolyte of lithium perchlorate in propylene carbonate in the voltage range 2.0–4.1 V vs Li/Li+, and concurrent optical transmittance modulation was studied at a wavelength of 530 nm. For the thickest films, the optical modulation range was as large as ~54% and the maximum transmittance was ~82% for deposition by AGD, whereas the corresponding numbers were ~45% and ~87% for MS. Rutherford backscattering spectrometry together with measurements of film thickness demonstrated that the porosity of 400–500-nm-thick films made by AGD and MS were ~84% and ~45%, respectively. The charge exchange per mass unit was as high as 48–67 C g–1 for samples made by AGD. The corresponding number was much lower for MS, namely 13–18 C g–1. These results lend convincing support to the view that the electrochromism of Ni-oxide-based films in Li-ion-conducting electrolytes is dominated by surface effects. [ABSTRACT FROM AUTHOR]

Poly(Azure A) (PAA) films doped with sodium dodecyl sulfate (SDS) were grown on transparent indium tin oxide (ITO) glass substrates by cyclic voltammetry. The electrochromism of PAA was investigated by digital video-electrochemistry (DVEC). DVEC consists of the acquisition of sequential digital images during the electro-stimulated changes of PAA color. The evolution of red, green, and blue (R, G, B) colors intensity (I) of analyzed pixels provides enough sensitivity to detect changes of some nmol cm-2 of electroactive centers. Besides, the different time evolution of these color intensities can serve to discern among different electroactive centers activated in the polymer. For the first time, contrast, coloration efficiency, and bleaching times of PAA are calculated by DVEC. The coloration efficiencies were between 15-25 cm2 mC-1 with short response times for the bleaching process between 2.9 and 5.5 s. PAA has good electrochromic performances to be used in electrochromic devices. Our present work provides an important insight into the design principles for a practical application of DVEC to characterize electrochromic devices in light-controlled conditions allowing us to find the best performances of these materials. [ABSTRACT FROM AUTHOR]

As a promising electrochromic material, WO3 frequently suffers from the cyclic degradation caused by trapped ions in the host structure. The intrinsic trapped sites in WO3 host structure usually are considered as the main contribution to the formation of trapped ions. In this study, by chronopotentiometry technology to quantify the diffused ions, we find that ions transport behavior plays a key role in the structural stability and the generation of trapped ions. Specifically, repeated insertion/extraction behavior will result in WO3 structure damage. As a result, the ions transport shows hysteretic kinetics in the subsequent reaction process, and the inserted Li+ ions in the coloration process can not be completely extracted, which contributes to the generation of the majority of trapped ions in film. Subsequently, the transmittance of the bleaching state and the optical modulation ability of WO3 film show serious decay. This work exhibits a new understanding of the degradation of electrochromic materials and offers an efficient method for WO3 to maintain a long-life performance. [ABSTRACT FROM AUTHOR]

Thin films of electrochromic W oxide and W–Ti oxide were prepared by reactive DC magnetron sputtering and were cycled voltammetrically in an electrolyte of lithium perchlorate in propylene carbonate. Film degradation was studied for up to 500 voltammetric cycles in voltage ranges between 1.5–4.0 and 2.0–4.0 V vs. Li/Li+. Optically and electrochemically degraded films were subjected to potentiostatic posttreatment at 6.0 V vs. Li/Li+ to achieve ion de-trapping and rejuvenation so that the films partly regained their original properties. Ti incorporation and potentiostatic posttreatment jointly yielded superior electrochromic properties provided the lower limit of the voltage range was above 1.6–1.7 V vs. Li/Li+. Degradation dynamics for as-deposited and rejuvenated thin films was modeled successfully by power-law kinetics; this analysis indicated coexistence of two degradation mechanisms, one based on dispersive chemical kinetics and operating universally and another, of unknown origin, rendered inactive by rejuvenation. The results of the present study are of large interest for the development of electrochromic devices with exceptional durability. [ABSTRACT FROM AUTHOR]

In this research, conducting polymer - polypyrrole (Ppy), was electrochemically polymerized on the indium tin oxide coated glass (glass/ITO) electrode. The adhesion of Ppy on the surface of ITO was improved by modification with triethoxymethylsilane (TEMS). Potential cycling was applied for electrochemical deposition of Ppy layer and cyclic voltammograms were recorded during the deposition tomonitor polymerization process. Cyclic voltammetry and the potential pulse sequence (PPS)-based chronoamperometry methods complemented the registration of absorbance spectra of glass/ITO(TEMS)/Ppy at various pH and different concentrations of CO2. The applicability of glass/ITO(TEMS)/Ppy electrode in the design of electrochromic sensor sensitive toward CO2 has been evaluated. Cyclic voltammetry based experiments at different potential sweep rates in presence and absence of CO2 were performed in order to evaluate charge transfer phenomenon in glass/ITO(TEMS)Ppy structure. [ABSTRACT FROM AUTHOR]

Conducting polymers have attracted attention as active materials for low power consuming, flexible devices with vivid colors and simple, room temperature processing methods. However, the conductive polymers with high-contrast electrochromic properties are limited in the literature. Here we achieve high-contrast electrochromic switching by copolymerization of newly synthesized an amide substituted dithienyl pyrrole (PBA) and 3,4-ethylenedioxythiophene (EDOT). In order to obtain the best optical properties of copolymer, spectral characteristics of the synthesized copolymers with different monomer feed ratios were investigated. Both homopolymer and copolymer films exhibit well defined redox and satisfied coloration efficiency. Spectroelectrochemistry studies indicate that the P(PBA-co-EDOT) has a lower bandgap (1.67 eV) and shows the excellent optical contrast (77% of 1000 nm) and coloration efficiency (697.01 cm2 C-1). The copolymer method provides a novel way to fabricate a freestanding organic electrochromic device. Additionally, the fluorescence properties of both monomer and polymer were investigated. P(PBA) having strong emission and good solubility and also P(PBA) has the potential to be used in OLEDs. [ABSTRACT FROM AUTHOR]

The electrochromic properties of 90:10 WO3/TiO2 thin films produced by anodizing co-sputtered W/Ti films in a fluorinated ethylene glycol solution are investigated in relation to corresponding pure W03 films. SEM images revealed that the TiO2 content resulted in a more open honey-comb structure that increased the charge accommodation ability by 250%. The superior charge storage property of the WO3/TiO2 meant that it had a better light modulation range, with transmittance of <1% at 800 nm in the colored state. The electrochromic kinetic processes associated with coloration and bleaching are also much faster in the presence of TiO2. with data generated by electrochemical impedance spectroscopy revealing that this is due to a reduction in the resistance to the insertion of Li+ ions. Materials characterization techniques revealed that the WO3/TiO2 composite maintains the monoclinic structure of the WO3 and that the Ti atoms are substituted into the WO3 matrix, rather than forming discrete TiO2 blocks. [ABSTRACT FROM AUTHOR]

A new star shape monomer, 2,4,6-tris((9H-carbazol-2-yl)oxy)-l,3,5-triazine (CTR) was synthesized. It was electrochemically polymerized in boron trifluoride diethyl etherate (BFEE)/acetonitrile (ACN) solvent couple. The interaction between BFEE and the CTR lowers the oxidation potential of the monomer and the catalytic effect of BFEE facilitated the formation of high quality polymer film. Electrochemically prepared P(CTR) film was characterized via CV, SEM, FT1R, TGA and UV-vis spectroscopy. Spectroelectrochemical analysis revealed that P(CTR) has high band gap energy which provide it colorless in the neutral state. Electronic transitions of the P(CTR) were observed at 327 and 650 nm, revealing π to π* transitions, and polaron band formation. The polymer switches between dark turquoise and transparent with a switching time of 1.5 s and an optical contrast (%ΔT) of 50%. Electrochromic studies revealed that P(CTR) has opposite properties to EDOT in terms of redox color. In addition to a dual-type complementary colored polymer electrochromic device based on P(CTR) and P(EDOT) was constructed in sandwich configuration. Spectroelectrochemical studies disclosed that the oxidized state of the device shows a blue color and it is transparent in the reduced state. Switching time and maximum contrast (%ΔT) of the device was measured as 3 s and 32% for 615 nm. [ABSTRACT FROM AUTHOR]

A novel conducting polymer, poly(aniline-co-N-methylthionine), is synthesized in a mildly acidic aqueous solution using cyclic voltammetry. The rate of copolymerization and the electrochemical properties of the obtained copolymers are substantially affected by pH, upper potential limit and comonomer concentration ratio. The copolymer possesses a high electrochemical activity in an aqueous solution up to pH 10.0. The copolymer formed on an indium-tin oxide glass electrode exhibits a black-to-transmissive electrochromism under relatively low potentials. The results from the Fourier transformed infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) of the copolymer show that NMTh units and Cl- ions were incorporated into the copolymer backbone during the electrosynthesis. The scanning electron microscopy (SEM) micrograph demonstrates that the copolymer film is composed of polymeric flower-like microparticles with an average diameter of 1 µm. [ABSTRACT FROM AUTHOR]

Metallophthalocyanines (MPcs) bearing octakis diethylamino-phenoxy substituents were oxidatively electropolymerized on the working electrode. Changing metal center of the Pc cores of MPcs (MPcs bearing octakis diethylamino-phenoxy (odea) groups; M = 2H+ (H2Pc-odea); Co2+ (CoPc-odea) and Cu2+ (CuPc-odea) alter the electropolymerization mechanisms and electrochemical responses of the electropolymerized films. Redox activities and insolubility of the electropolymerized films of the complexes provided usage of the complexes in different electrolytic media as electroactive materials. For electrochromic applications, thin films of the complexes were coated on ITO electrodes and ITO/MPc-odea electrodes were constructed. Then electrochromic properties of ITO/MPc-odea electrodes were studied in detail with various electrochemical, in-situ spectroelectrochemical and in-situ electrocolorimetric analysis methods. While ITO/H2Pc-odea did not give any spectral changes in different electrolytes, both of ITO/CuPc-odea and ITO/CoPc-odea gave excellent electrochromic responses with distinct color changes, fast response times, high optical contrast and reasonable optical and coulombic stabilities. [ABSTRACT FROM AUTHOR]

Nanostructured tungsten oxide films for electrochromic applications are fabricated by using a new method - vacuum filtration and transfer onto Indium Tin Oxide (ITO) substrates. It is found that the thickness and morphology of the film depend on the size of nanoparticles, the amount of the filtrated material, the pore size of the membrane, and the temperature of the post-deposition heat-treatment. The films show interesting and quite unexpected electrochromic properties, especially regarding the response time. Compared to films fabricated through sol-gel methods, the response time, especially, the bleaching time, is considerably shorter, in spite of the larger thickness of the filtrated films. As shown by chronoamperometry measurements, the bleaching process is considerably faster than the coloring. This characteristic is reinforced by the diffusion coefficients calculated from both cyclic voltammetry and electrical impedance spectroscopy data. The vacuum filtration method proved to be well-suited for the fabrication of electrochromic films based on single materials and can be easily extended to doped materials and mixtures. [ABSTRACT FROM AUTHOR]

The graphene/poly (ethylene oxide)/V2O5· nH2O films (GPV) were fabricated by sol-gel method. The structure of the ternary nanocomposite films were investigated by X-Ray Diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). V2O5· nH2O layered structure was intercalated by poly (ethylene oxide) (PEO) and graphene. The electrochemical properties of the nanocomposite films were measured by the cyclic voltammetry (CV) and chronoamperometry (CA) measurements with the standard three-electrode configuration. The optical properties were characterized by ultraviolet-visible spectrophotometer. The electrochromic response rate of the GPV films is enhanced evidently. Its bleaching time is 1.8 second, and the coloration time is 3.8 second. These results demonstrate that the GPV films have a potential application in the fast switching electrochromic devices. [ABSTRACT FROM AUTHOR]

Electrochromic responses of metallophthalocyanines (MPcs) bearing redox active and electropolymerizable substituents were investigated. Excellent electrochromic responses were observed for metal-free and nickel phthalocyanines bearing electropolymerizable tetrahydroquinoline moieties (Phthalocyanine bearing 2,2,4,7-tetramethyl-3,4-dihydroquinoline, (THQ)) dyads; H2Pc-THQD and NiPc-DHQD). Although MPcs were not electropolymerizable complexes, they were easily electropolymerized on the working electrode after substituting with DHQ moieties. In order to investigate electrochromic features of the complexes, electrochemical and in-situ spectrochronocoulometric analyses of H2Pc-THQD andwere first of all performed in solution and in solid states as their electropolymerized films to derive their possible usage as electrochromic materials. While both complexes gave common Pc ring based reduction reactions, they were coated on the working electrode with electropolymerization during oxidation reactions. Presence of THQ substituents caused electropolymerization of the complexes during the oxidation reactions. Then in order to examine their possible usages in the electrochromic application fields, phthalocyanine based composite electrodes were prepared with oxidative electropolymerization reactions. Finally their electrochromic features were investigated in different electrolyte systems. Electrochromic measurements showed that the electrodes modified with the electropolymerized films of H2Pc-THQD and NiPc-DHQD enhanced electrochromic properties to MPcs considerably. H2Pc-THQD and complexes illustrated excellent electrochromic parameters with high optical contrast, reasonable optical and columbic stabilities, and short response times. [ABSTRACT FROM AUTHOR]

Self-powered systems usually consist of energy-acquisition components, energy-storage components and functional components. The development of nanoscience and nanotechnology has greatly improved the performance of all the components of self-powered systems. However, huge differences in the materials and configurations in the components cause large difficulties for integration and miniaturization of self-powered systems. Design and fabrication of different components in a self-powered system with the same or similar materials/configurations should be able to make the above goal easier. In this work, a proof-of-concept experiment involving an integrated self-powered color-changing system consisting of TiO2 nanowire based sandwich dye-sensitized solar cells (DSSCs) and electrochromic devices (ECDs) is designed and demonstrated. When sunlight illuminates the entire system, the DSSCs generate electrical power and turn the ECD to a darker color, dimming the light; by switching the connection polarity of the DSSCs, the lighter color can be regained, implying the potential application of this self-powered color-changing system for next generation sun glasses and smart windows. [ABSTRACT FROM AUTHOR]

Poly(4,4',4''-tris[4-(2-bithienyl)pheny]amine) (PTBTPA) was electrochemically synthesized on a ZnO-coated ITO electrode to form a PTBTPA/ZnO nanocomposite electrode. The composite film exhibited a noticeable electrochromism, with reversible color changes from orange in the reduced state (0 V), olive green in the middle state (0.9 V) to dark gray in the oxidized state (1.2 V). Furthermore, the composite film showed a fast switching time of 0.92 s and a high optical contrast of 65% at 1100 nm, and retained 97% of its original electroactivity after 500 cycles, while PTBTPA film had switching time of 1.63 s and an optical contrast of 52% at 1100 nm, and retained 75% of its original electroactivity. The results demonstrated that the electrochromic performances were significantly enhanced through incorporating PTBTPA with ZnO nanorods. ZnO nanorods were introduced to modify the structure of the electrode: on one hand, to offer a directional attraction for the counterions, and on the other hand, to enhance the adhesion between the polymer and the ITO electrode. Accordingly, a conducting polymer/inorganic nanocomposite system could improve the polymer's electrochromic performance, especially in terms of the switching speed and long-term stability of the electrochromic materials. [ABSTRACT FROM AUTHOR]

Vanadium/titanium mixed oxide films were produced using the sol-gel route. The structural investigation revealed that increased TiO2 molar ratio in the mixed oxide disturbs the V2O5 crystalline structure and makes it amorphous. This blocks the TiO2 phase transformation, so TiO2 stabilizes in the anatase phase. In addition the surface of the sample always presents larger amounts of TiO2 than expected, revealing a concentration gradient along the growth direction. For increased TiO2 molar ratios the roughness of the surface is reduced. Ion sensors were fabricated using the extended gate field effect transistor configuration. The obtained sensitivities varied in the range of 58 mV/pH down to 15 mV/pH according to the composition and morphology of the surface of the samples. Low TiO2 amounts presented better sensing properties that might be related to the cracked and inhomogeneous surfaces. Rising the TiO2 quantity in the films produces homogeneous surfaces but diminishes their sensitivities. Thus, the present paper reveals that the compositional and structural aspects change the surface morphology and electrical properties accounting for the final ion sensing properties of the V2O5/TiO2 films. [ABSTRACT FROM AUTHOR]

A synthesis technique which can lead to direct integration of tungsten oxide nanowires onto silicon chips is essential for preparing various devices. The conversion of amorphous tungsten films deposited on silicon chips by pulsed layer deposition to nanowires by annealing is an apt method in that direction. This perspective discusses the ingenious features of the technique reported by Dellasega et al on the various aspects of tungsten oxide nanowire synthesis. [ABSTRACT FROM AUTHOR]

Lithium titanate nanotubes (Li-TNTs) have been successfully synthesized. The inner and outer diameters of the nanotubes are 5 nm and 8 nm with an interlayer spacing of 0.83 nm. The nanotubes were in accordance with the Li1.81H0.19Ti2O5 · xH2O phase. The chemical component was Li0.9H1.1Ti2O5 · H2O as determined by ICP-AES. The Li-TNT-supported WO3 nanoparticle (WO3/Li-TNTs) thin film was prepared onto ITO glass via spin-coating and then fabricated with an electrochromic device. The Li ion diffusion coefficient in the WO3/Li-TNT film was 6.1 × 10−10 cm2 s−1, which is eight times higher than that for the pure WO3 film. The transmittance contrast of the pure WO3-based ECD was 53.3% at 600 nm. However, this increased to 74.1% for the WO3/Li-TNT-based ECD. Meanwhile, the color-switching times of the WO3/Li-TNT-based ECD were apparently shorter than the ones for the WO3-based ECD. [ABSTRACT FROM AUTHOR]

Progress in electrochromic lithium ion batteries (LIBs) is reviewed, highlighting advances and possible research directions. Methods for using the LIB electrode materials’ magnetic properties are also described, using several examples. Li4Ti5O12 (LTO) film is discussed as an electrochromic material and insertion compound. The opto-electrical properties of the LTO film have been characterized by electrical measurements and UV–Vis spectra. A prototype bi-functional electrochromic LIB, incorporating LTO as both electrochromic layer and anode, has also been characterized by charge– discharge measurements and UV–Vis transmittance. The results show that the bi-functional electrochromic LIB prototype works well. Magnetic measurement has proven to be a powerful tool to evaluate the quality of electrode materials. We introduce briefly the magnetism of solids in general, and then discuss the magnetic characteristics of layered oxides, spinel oxides, olivine phosphate LiFePO4, and Nasicon-type Li3Fe2(PO4)3. We also discuss what kind of impurities can be detected, which will guide us to fabricate high quality films and high performance devices. [ABSTRACT FROM AUTHOR]

The typical applications of electrochromic devices do not make use of the charge-dependent, gradual optical response due to their slow voltage-sensitive coloration. However, in this paper we present a design for a reusable, self-powered light dose indicator consisting of a solar cell and a gyroid-structured nickel oxide (NiO) electrochromic display that measures the cumulative charge per se, making use of the efficient voltage-sensitive coloration of gyroid materials. To circumvent the stability issues associated with the standard aqueous electrolyte that is typically accompanied by water splitting and gas evolution, we investigate a novel nano-gyroid NiO electrochromic device based on organic solvents of 1,1,1,3,3,3-hexafluoropropan-2-ol, and room temperature ionic liquid (RTIL) triethylsulfonium bis(trifluoromethylsulfonyl) imide ([SET3][TFSI]) containing lithium bis(trifluoromethylsulfonyl) imide. We show that an effective light dose indicator can be enabled by nano-gyroid NiO with RTIL; this proves to be a reliable device since it does not involve solvent degradation or gas generation. [ABSTRACT FROM AUTHOR]

Electrochromic WO3 films are prepared by the electron-beam evaporation method. The as-deposited films are amorphous in structure. The optical transmittance spectra show 13.4% decay of optical modulation after 20 electrochemical cycles. The degradation behaviour of the WO3 films is also observed in electrochemical step potential measurements. X-ray absorption spectroscopy indicates that the absorption energy of the W LIII-edge shifts towards lower energy with the insertion of Li+ ions and electrons. The results of radial distribution functions reveal that the increase in the distance of the W–O bonds is caused by the reduction in W ions. LixWO3 and Li2WO4 are formed at −0.5 V and −1.0 V, respectively, during electrochemical insertion, as observed by transmission electron microscopy. The Raman scattering analysis indicates that only two ionic states, W4+ and W6+, exist in the WO3 films, due to excess injection of electrons and Li+ ions. We suggest that the degradation of the electrochromic properties of the WO3 films during electrochemical cycles is related to the formation of different W ionic states. [ABSTRACT FROM AUTHOR]